INCH-POUNDMIL-HDBK-113831 OCTOBER 1997SUPERSEDING

TM 5-665 MO-212

AFM 91-32JANUARY 1982

DEPARTMENT OF DEFENSEHANDBOOK

WASTEWATER TREATMENT SYSTEMOPERATIONS AND MAINTENANCE

AUGMENTING HANDBOOK

AMSC N/A AREA FACR

Distribution Statement A. APPROVED FOR PUBLIC RELEASE:DISTRIBUTION IS UNLIMITED.

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ABSTRACT

This handbook augments the series of O&M field study trainingmanuals prepared by California State University, Sacramento, andthe California Water Pollution Control Association for the UnitedStates Environmental Protection Agency (EPA). This series,commonly known as the "Sacramento" series, has been adopted foruse by the military. It addresses most topics pertinent towastewater treatment O&M. However, some topics important tomilitary facilities are not sufficiently covered in the Sacramentoseries or require particular emphasis. This handbook addressesthose topics and includes the following: regulatory complianceand monitoring; septic tanks; grease traps; oil/water separators;septage management; extreme climate operation; corrosion control;and chemical shipping and feeding.

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FOREWORD

This handbook is approved for use by all Departments and Agenciesof the Department of Defense. It is intended to guide the readerin the operations and maintenance of wastewater treatment systems.Commercial equipment and materials mentioned in this handbook areincluded for illustration purposes and do not constitute anendorsement.

Beneficial comments (recommendations, additions, deletions) andany pertinent data which may be of use in improving this documentor the Sacramento Series should be submitted on the DD Form 1426,Standardization Document Improvement Proposal, and addressedthrough major commands to:

Air Force: HQ AFCESA/CESC, 139 Barnes Dr., Suite 1, Tyndall AFB,FL 32403-5319.

Army: U.S. Army Center for Public Works, ATTN: CECPW-ES,7701 Telegraph Rd., Alexandria, VA 22315-3862

Navy: LANTNAVFACENGCOM, Code 161B, 1510 Gilbert St.,Norfolk, VA 23511-2699

DO NOT USE THIS HANDBOOK AS A REFERENCE IN A PROCUREMENT DOCUMENTFOR FACILITIES CONSTRUCTION. IT IS TO BE USED IN THE PURCHASE ANDPREPARATION OF FACILITIES PLANNING AND ENGINEERING STUDIES ANDDESIGN DOCUMENTS USED FOR THE PROCUREMENT OF FACILITIESCONSTRUCTION (SCOPE, BASIS OF DESIGN, TECHNICAL REQUIREMENTS,PLANS, SPECIFICATIONS, COST ESTIMATES, REQUEST FOR PROPOSALS, ANDINVITATION FOR BIDS). DO NOT REFERENCE IT IN MILITARY OR FEDERALSPECIFICATIONS OR OTHER PROCUREMENT DOCUMENTS.

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WASTEWATER TREATMENT SYSTEM O&M CRITERIA MANUALS

Military-adopted commercial wastewater treatment system O&Mguidance (from the Sacramento series of field study trainingmanuals):

Operation of Wastewater Treatment Plants, Volume 1Operation of Wastewater Treatment Plants, Volume 2Operation and Maintenance of Wastewater Collection Systems, Volume 1Operation and Maintenance of Wastewater Collection Systems, Volume 2Industrial Waste Treatment, Volume 1Industrial Waste Treatment, Volume 2Advanced Waste TreatmentTreatment of Metal Wastestreams

Although not adopted by the military as a commercial O&M guidancedocument, the final manual in the Sacramento series, PretreatmentFacility Inspection, may be valuable to environmental officesresponsible for environmental compliance.

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WASTEWATER TREATMENT SYSTEMOPERATIONS AND MAINTENANCE GUIDANCE DOCUMENT

AUGMENTING HANDBOOK

CONTENTS Page

Section 1 INTRODUCTION1.1 Scope of This Handbook.................... 11.1.1 Primary O&M Guidance Document............. 11.1.2 Augmenting Handbook....................... 21.2 Organization of Handbook.................. 21.3 Cancellation.............................. 2

Section 2 REGULATORY COMPLIANCE AND MONITORING2.1 Federally Owned Treatment Works (FOTWs)... 32.1.1 FOTW Provisions........................... 32.1.1.1 Hazardous Waste Exclusion Requirements.... 32.1.1.2 Special Provisions........................ 32.2 Permitting Requirements................... 42.2.1 FOTW Permits.............................. 42.2.1.1 Operating NPDES Permit.................... 52.2.1.2 Permits for Other Disposal Options........ 52.2.1.3 Stormwater NPDES Permit................... 52.2.1.4 Solids NPDES Permit....................... 62.2.2 NPDES Compliance.......................... 62.2.3 Permit Renewal............................ 62.2.3.1 Capacity Analysis Report.................. 72.2.3.2 Operation and Maintenance Report.......... 82.2.3.3 Preliminary Engineering/Feasibility

Report.................................... 82.2.3.4 Permit Application Forms.................. 82.3 Operator Certification.................... 92.3.1 Definition................................ 92.3.2 Benefits of Obtaining Certification....... 92.3.3 FOTW Requirements......................... 92.3.4 Attaining Certification................... 92.3.5 Training for Certification................ 102.4 Current Trends in the Wastewater Industry

That Affect Plant Operations.............. 102.4.1 Water Quality-Based Effluent Limits....... 102.4.1.1 Waste Load Allocation..................... 112.4.1.2 Chemical-Specific Criteria................ 112.4.1.3 Aquatic Life Criteria..................... 122.4.1.4 General Narrative Criteria................ 122.4.1.5 Negotiation of Effluent Limits............ 122.4.2 Wastewater Reuse.......................... 12

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Page2.4.2.1 Reuse Feasibility Study................... 132.4.2.2 Reuse Treatment Facilities................ 132.4.3 40 CFR Part 503 Sludge Regulations........ 132.4.3.1 Solids Definitions........................ 142.4.3.2 Protection of Public Health and the

Environment............................... 152.4.3.3 Applicability of the Requirements

[503.15].................................. 172.4.3.4 Requirements for Land Application or

Disposal.................................. 172.4.3.5 Pathogen Reduction Requirements........... 172.4.3.6 Vector Attraction Reduction Requirements

[503.33].................................. 182.4.3.7 Frequency of Monitoring................... 182.4.3.8 Recordkeeping Requirements [503.17

and 503.27]............................... 192.4.3.9 Reporting Requirements for Sewage Solids

[503.18 and 503.28]....................... 192.4.3.10 Permits and Direct Enforceability [503.3]. 20

Section 3 SEPTIC TANKS3.1 Description............................... 213.1.1 System Components......................... 213.1.1.1 Tank...................................... 213.1.1.2 Effluent Leaching Systems................. 213.1.2 System Operation Principles............... 233.2 Septic Tank System O&M.................... 233.2.1 Inspecting the Septic Tank................ 233.2.1.1 Measuring Solids and Scum Inside the Tank. 233.2.2 Removal of Settleable Solids.............. 243.2.3 Monitoring Waste Discharged to System..... 253.2.4 Water Conservation........................ 253.2.5 Vegetation Over System Components......... 253.3 Leachate System O&M....................... 253.4 Septic Tank System Failures............... 26

Section 4 GREASE TRAPS4.1 Description............................... 284.1.1 Configuration............................. 284.1.2 Location.................................. 284.1.3 Discharges to Grease Traps................ 284.2 Maintenance Procedures.................... 284.2.1 Pump-Out Frequency........................ 294.2.2 Maintenance Specific to Manufactured

Grease-Removal Systems................... 29

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PageSection 5 OIL/WATER SEPARATORS

5.1 Oil/Water Separators..................... 305.2 Types of Oil/Water Separators............ 305.2.1 Gravity Separators....................... 305.2.1.1 Conventional Gravity-Type Separators..... 315.2.1.2 Corrugated Plate Interceptors............ 315.2.2 Dissolved Air Flotation (DAF)............ 345.3 Problems with Oil/Water Separator

Applications............................. 365.3.1 Frequency and Intensity of Flow.......... 365.3.2 Design Capacity.......................... 375.3.3 Emulsifying Agents....................... 375.3.4 Periodic Maintenance Practices........... 375.3.5 Type of Oil/Water Separator System....... 385.3.6 Contaminants in Wastewater Stream........ 385.4 Evaluation of Need for Oil/Water

Separators............................... 385.5 O&M of Oil/Water Separators.............. 425.6 Guidance Documents....................... 44

Section 6 SEPTAGE MANAGEMENT6.1 Septage Management Alternatives.......... 456.2 Septage Characterization................. 456.2.1 Septage Quantity......................... 456.2.2 Characteristics of Septage............... 466.2.3 Comparison of Septage and Domestic

Wastewater Characteristics............... 466.3 Monitoring the Quantity and Quality of

Incoming Septage......................... 466.3.1 Monitoring Procedures.................... 486.3.2 Sampling................................. 496.3.3 Recordkeeping............................ 496.4 Modes of Septage Treatment............... 496.4.1 Estimating Treatment Capacity............ 506.4.2 Co-Treatment of Septage in Liquid Stream. 506.4.3 Co-Treatment of Septage in Solids Stream. 516.5 Receiving Station........................ 526.5.1 Receiving Station Description............ 526.5.2 Dumping Station.......................... 526.5.3 Screening Facility....................... 536.5.4 Grit Removal System...................... 536.5.5 Grinder Pump Stations.................... 536.5.6 Storage and Equalization.................. 536.5.7 Lift Station.............................. 546.5.8 Odor Control Capability................... 54

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PageSection 7 EXTREME CLIMATE OPERATION

7.1 Effects of Extreme Cold Climates.......... 557.2 Preliminary Treatment Processes........... 557.2.1 Screens and Grinders...................... 587.2.2 Grit Removal Processes.................... 587.2.3 Flow Measurement.......................... 597.2.4 Other Preliminary Treatment Processes..... 597.3 Clarifiers................................ 607.3.1 Surface Freezing Conditions............... 607.3.2 Mechanical and Electrical Equipment

Protection................................ 627.3.3 Process Concerns.......................... 627.4 Biological Systems........................ 627.4.1 Activated Sludge Systems.................. 647.4.2 Fixed Film Treatment Systems.............. 647.4.3 Lagoon Systems............................ 657.5 Disinfection.............................. 657.6 Solids Management......................... 667.6.1 Aerobic Digesters......................... 667.6.2 Anaerobic Digesters....................... 677.6.3 Dewatering................................ 677.6.4 Equipment Maintenance..................... 677.6.5 Concrete Repair........................... 67

Section 8 CORROSION CONTROL8.1 Causes of Corrosion....................... 698.1.1 Electrochemical Corrosion................. 698.1.2 Eight Forms of Corrosion.................. 708.1.2.1 Uniform Corrosion......................... 718.1.2.2 Galvanic Corrosion........................ 718.1.2.3 Crevice Corrosion......................... 738.1.2.4 Pitting Corrosion......................... 748.1.2.5 Intergranular Corrosion................... 748.1.2.6 Selective Leaching........................ 758.1.2.7 Erosion Corrosion......................... 758.1.2.8 Stress Corrosion.......................... 768.2 Control and Minimization of Corrosion..... 768.2.1 Protective Coatings....................... 768.2.1.1 Surface Preparation....................... 778.2.1.2 Coating Systems for Metals................ 788.2.1.3 Coating Systems for Concrete.............. 798.2.1.4 Coating Application....................... 798.2.2 Cathodic Protection....................... 808.2.3 Materials of Construction................. 808.2.3.1 Metals.................................... 81

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Page8.2.3.2 Nonmetals................................. 81

Section 9 CHEMICAL SHIPPING AND FEEDING9.1 Sources of Information.................... 82

APPENDIXES

APPENDIX A Sacramento Series Training Manual Contents.....105APPENDIX B Sacramento Series Cross Reference..............108APPENDIX C WWTP Operator Certification Contact List.......113

FIGURES

Figure 1 Definitions of Solids.......................... 162 Typical Two-Compartment Septic Tank............ 223 Conventional Gravity Separator................. 324 Process Schematic of CPI Separator............. 335 Process Schematic of Dissolved Air Flotation... 356 Decision Tree for Pretreatment of Oily Waste... 407 Electrochemical Corrosion Cell................. 708 Galvanic Corrosion Cell........................ 72

TABLES

Table 1 Estimated Septic Tank Pumping Frequenciesin Years....................................... 24

2 Maintenance Checklist for Septic TankSystem Failures................................ 26

3 Recommended Inspection Points forOil/Water Separators........................... 43

4 Physical and Chemical Characteristicsof Septage..................................... 47

5 Comparison of Septage and Domestic Wastewater.. 486 Treatment Process Components Subject to

Freezing Problems.............................. 567 Winter Problems with Preliminary Treatment..... 568 Winter Problems with Clarifiers................ 609 Winter Problems with Biological Systems........ 6310 Winter Disinfection Problems................... 6511 Winter Problems with Solids Management......... 6612 Practical Galvanic Series of Metals............ 7313 Surface Preparation Standards.................. 78

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Page14 Chemical Shipping Data and Characteristics.... 8315 Chemical-Specific Feeding Recommendations..... 94

BIBLIOGRAPHY ..............................................114

REFERENCES ..............................................115

GLOSSARY ..............................................118

CONCLUDING MATERIAL..........................................120

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Page

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Section 1: INTRODUCTION

1.1 Scope of This Handbook. This handbook providestechnical guidance for operations and maintenance (O&M) ofwastewater treatment systems. It supplements site-specific O&Mmanuals and a military-approved set of commercial O&M guidancedocuments. Those documents, commonly known as the “Sacramento”series of O&M field study training manuals, have been adopted bythe military for use in wastewater treatment facilities atmilitary installations.

1.1.1 Primary O&M Guidance Document. The Sacramento series isthe primary technical guidance source for O&M of wastewatertreatment systems. The Sacramento series is a set of nine volumesprepared by the California State University, Sacramento, incooperation with the California Water Pollution ControlAssociation, for the United States Environmental Protection Agency(EPA). The series includes the following publications:

a) Operation of Wastewater Treatment Plants, Volume 1

b) Operation of Wastewater Treatment Plants, Volume 2

c) Operation and Maintenance of Wastewater CollectionSystems, Volume 1

d) Operation and Maintenance of Wastewater CollectionSystems, Volume 2

e) Industrial Waste Treatment, Volume 1

f) Industrial Waste Treatment, Volume 2

g) Advanced Waste Treatment

h) Treatment of Metal Wastestreams

i) Pretreatment Facility Inspection

The final volume in this series, Pretreatment FacilityInspection, has not been adopted by the military as an O&Mguidance document. However, it may prove a valuable resource forenvironmental office personnel responsible for environmentalcompliance. Operations personnel at each installation are advisedto obtain those volumes pertinent to their wastewater treatmentsystem. Most installations will not require all the volumes.

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MIL-HDBK-353, Planning and Commissioning WastewaterTreatment Plants, provides additional information useful tooperators planning or in the process of constructing new orupgraded wastewater treatment systems.

1.1.2 Augmenting Handbook. This handbook provides technicalguidance on topics that are not covered in the Sacramento seriesor that deserve special emphasis. Both the Sacramento series andthis handbook apply to all personnel responsible for operating andmaintaining fixed-base wastewater treatment systems, includingdecision makers, mid-level managers, and operators.

1.2 Organization of Handbook. It is suggested that thereader become familiar with the organization, content, andintended use of this handbook by first looking at the table ofcontents.

To aid the reader in locating other topics concerningwastewater treatment systems, a list of chapter titles for each ofthe Sacramento series manuals has been included as Appendix A.Appendix B provides a cross reference for readers, listing eachtopic along with the section location in this handbook andcorresponding chapter in the Sacramento Series volumes thatcontain the referenced information.

1.3 Cancellation. This handbook supersedes TM 5-655, MO212, and AFM 91-32, Operation and Maintenance of Domestic andIndustrial Wastewater Systems.

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Section 2: REGULATORY COMPLIANCE AND MONITORING

2.1 Federally Owned Treatment Works (FOTWs). Generally,FOTWs are operated and administered under the same permitting andoperational provisions set forth for publicly owned treatmentworks (POTWs). That is, these facilities usually comply with theconstruction permitting, operational permitting, and effluentdischarge and residuals handling permitting requirements asadministered by individual states and/or the EPA.

Operations and management staff at FOTWs are expected tounderstand and comply with these requirements and to keep theinstallation's environmental office informed of any problems thatmay affect compliance. A review of the general requirements forpermitting, monitoring, and reporting appears below in par. 2.2.Operator training and certification needs are covered in par. 2.3.Trends that affect plant operations are discussed in par. 2.4,including a description of water quality-based effluent limits,wastewater reuse, the Part 503 sludge regulations and beneficialreuse of sludge, and operations certification programs.

2.1.1 FOTW Provisions. One area in which FOTWs areadministered differently from POTWs is the pretreatment programrequirements and a limited provision to exclude POTW hazardouswaste from some regulation under the Resource Conservation andRecovery Act (RCRA). These differences are discussed in thefollowing subparagraphs.

2.1.1.1 Hazardous Waste Exclusion Requirements. It is unlawfulto introduce into an FOTW any pollutant that is a hazardous waste.POTWs are excluded from this hazardous waste restriction becauseof special provisions for POTWs in the RCRA regulations. POTWsmust comply with pretreatment programs to ensure that commercialand industrial contributors to the collection system do notdeposit excess hazardous or toxic materials/waste into the sewersystem. Such pretreatment program standards are not required forFOTWs, although military FOTWs have generally followed them.

2.1.1.2 Special Provisions. A military wastewater treatmentworks qualifies for FOTW status and the potential for exclusionunder RCRA Section 3023, 42 USC Section 6939e, if the treatmentworks is owned or operated by the DoD, if the majority of theinfluent received at the treatment works is domestic wastewater,and if the effluent of the treatment works is discharged to a

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surface water under a National Pollutant Discharge EliminationSystem (NPDES) permit. There are additional hazardous wastequantity and pretreatment requirements for dischargers to FOTWs.The relationship between military FOTWs and each activity orfacility that discharges industrial process waste or other non-domestic wastewater should be controlled by local installationpolicies and instructions. Operating personnel should contact theinstallation’s environmental office if they find hazardous wasteor if a shop or other activity requests permission to discharge ahazardous waste in the collection system.

2.2 Permitting Requirements. Permits are issued for theconstruction or modification of FOTWs, discharge of treatedeffluent, discharge of stormwater runoff, and solids managementpractices. These permits can be issued by Federal (EPA), state,or local governments. Sometimes all three levels of governmentissue separate permits. More often, the FOTW operating permitsare combined. This discussion focuses primarily on Federalpermits.

Plant operations staff should coordinate with theenvironmental office in the permitting process. Generalpermitting requirements are discussed in the subparagraphs belowto alert operations staff to areas where they may assist theenvironmental office.

2.2.1 FOTW Permits. The Code of Federal RegulationsSection 40 (40 CFR) Part 122 describes the NPDES permittingprogram used by the Federal Government to control pollution in theenvironment. The NPDES permit program has separate regulationsfound in 40 CFR Parts 125, 129, 133, 136, 400 through 460, and503. Nothing in the Federal rules precludes individual statesfrom having more stringent requirements. The NPDES program ismanaged by EPA, but many states have received authorization toissue permits and administer the program on a day-to-day basis.In these states, a single permit is issued from the state andFederal governments. FOTW operators need to know if their statehas been delegated the operation of the NPDES program.

Responsibility for the NPDES permit cannot be delegatedbelow the state level, so local governments may have separaterequirements. FOTW operators should check with theirinstallation's environmental office to determine what localrequirements may also pertain. Local governments are ofteninvolved with emergency reporting requirements in permits.

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2.2.1.1 Operating NPDES Permit. An NPDES operating permit isrequired before an FOTW can discharge any process water intosurface waters of the state. A valid NPDES permit will identifythe owner, describe the process, describe the discharge locationand frequency, and contain specific and general conditions.

Some states also have their own discharge permittingprogram. This program requires the permittee to obtain a statedischarge permit in addition to the NPDES discharge permit. TheNPDES permit program can be administered either by the regionalEPA office or by the states that have obtained authorization withEPA oversight. Those states that have obtained the NPDES programare said to have “NPDES primacy.” Typically, states with NPDESprimacy incorporate any unique state requirements into the NPDESpermit.

An NPDES permit is not a construction permit. In somestates, an owner may construct or modify a facility, but it is aviolation to place the modified facility in operation until avalid operating permit is obtained. Other states limit allconstruction activities until the changes or modifications areapproved. Your environmental office should review any change ormodification to the process with the permitting agency beforeimplementation to determine if a permit modification is required.Operations staff should be aware of both state and EPA surfacewater discharge requirements. Contact your installation’senvironmental office for this information.

2.2.1.2 Permits for Other Disposal Options. Treated effluentthat is entirely disposed into the groundwater or onto landapplication sites does not need an NPDES permit from EPA todischarge, but it may be subject to NPDES permits for stormwateror solids. (In addition to treated wastewater, NPDES permits canalso address stormwater and solids.) The state may also establishgroundwater monitoring or discharge requirements. For example,disposal of treated effluent to the subsurface will require anUnderground Injection Control (UIC) permit from the state asrequired by the Safe Drinking Water Act (SDWA).

2.2.1.3 Stormwater NPDES Permit. FOTWs that treat more than1 million gallons per day (mgd) are included in the stormwaterNPDES permitting program as a categorical industrial facility.Although stormwater could be included in the operating permitdescribed above, most facilities obtain a general stormwater NPDESpermit. This permit is maintained separately from the operatingpermit. Its requirements typically involve developing a

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stormwater pollution prevention plan, visually monitoring runoffon a quarterly basis, routinely inspecting the stormwater system,and maintaining records onsite. Your environmental office shouldcontact the NPDES authority to obtain the necessary stormwaterpermit information. EPA delegates operation of the stormwaterprogram to the local government as much as possible. The localstormwater program may be separate from the wastewater program andmay require special reporting or applications.

2.2.1.4 Solids NPDES Permit. FOTW residual solids managementhas received special attention under the Federal program (40 CFRPart 503). Solids management will typically be addressed as partof the FOTW operating permit. However, if there is no surfacedischarge and, consequently, no discharge permit, an NPDES permitfor the solids may still be required. Par. 2.4.3 covers Part 503sludge regulations.

2.2.2 NPDES Compliance. Failing to comply with the NPDESpermit may result in fines and other penalties. In some cases, itmay even result in criminal prosecution. The specific and generalconditions in the permit are the compliance provisions.Monitoring reports and emergency conditions bear special note.Since the NPDES program relies on self-reporting forimplementation, EPA places special emphasis on timely and completereporting. Enforcement actions are often swift and severe forbeing late with the monthly operating reports or for failing toreport violations. Emergency failures or spills typically requirenotice within 24 hours to the agencies.

Exceedance of water quality limits will also drawregulatory attention and possible enforcement action. Someparameters, like residual chlorine, cannot always be monitored atthe low permit limit levels. The FOTW operator needs to be surethat readings below detection limits are properly reported on themonthly operating reports. Compliance exceedances because ofprocess failures or overloading need to be corrected in a timelymanner. Sometimes the permitting agency will enter into acompliance implementation schedule to allow the treatment facilitytime to come into compliance. However, proactive planning priorto the permit renewal application can reduce the likelihood ofenforcement actions.

2.2.3 Permit Renewal. NPDES permits are valid for 5 years butmay be modified at earlier intervals by regulators. Permitrenewal applications need to be submitted 180 days (about6 months) before the expiration date. Ideally, preparation for

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the application begins approximately 1 year before the permitapplication is due. Preparation involves assessing plantperformance and improvement needs and conducting the necessaryplanning and design required to keep the facility in compliance.Your installation’s environmental office may ask you to assist inevaluating performance needs by assisting with development orreview of a Capacity Analysis Report and an Operation andMaintenance Report, as described below. These reports aretypically conducted by licensed engineering staff with operationsstaff input. Each of these reports may take a couple of months todevelop and may lead to additional work, so a 1-year lead time isnot excessive.

If the permit renewal is due and the assessments are notcomplete, the FOTW still needs to apply 180 days before thedeadline. Failure to apply in a timely manner is a permitviolation. If you have objections to your existing or proposedpermit you must file them during the official comment period.Even if your changes are not adopted, you are on record with theobjections, making it easier to negotiate changes at a later date.Changes to the permit can be applied for at any time during thepermit duration. There may be an additional fee for each permitmodification application. Combining requests for changes with thepermit renewal application is often convenient. If the existingpermit is being violated regularly, the FOTW may need to conductthe following assessments and act before permit expiration.

2.2.3.1 Capacity Analysis Report. This report documents thepredicted future flows and loads within the treatment facility,and evaluates the capacity of existing unit processes to reliablytreat those loads for the next permitting cycle. The historicalflows and the treatment performance of the preceding 5 years needto be analyzed. The carbonaceous biochemical oxygen demand (CBOD)and total suspended solids (TSS) loading (in pounds per day) alsoneed to be verified. Population, flow, and load projections arethen made to estimate what future loads will be, based onhistorical growth trends. The capacity of each unit process needsto be determined. Note that these capacity assessments mayalready have been done for past renewals. However, the capacityrating of each process needs to be checked against the latestloadings and flow. Reliability and backup provisions must also beadequate.

Finally, an assessment of the future 5-year flow andloads needs to be conducted. New mission and realignmentdecisions must be incorporated and future projections considered.

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If the plant is undersized, then an expansion needs to beinitiated and a Preliminary Engineering Report for improvementsdeveloped. Higher discharge rates will also precipitateadditional permit application requirements to addressantidegradation issues.

2.2.3.2 Operation and Maintenance Report. This report reviewsplant operations data over the last permit cycle to evaluateneeded improvements to the facility. Any upsets orspills need to be reviewed to determine the cause and possiblesolution. Some water quality exceedances may be a result ofoperation practices and need to be reviewed. The condition of thefacilities is evaluated, such as the need for painting and otherroutine maintenance. Some needs may require changes to theprocess or construction approval. Permit renewal is a good timeto include major changes. However, not every maintenance itemneeds to be reported to the agencies. Confirmation from theagency on which items need permitting is recommended after theOperation and Maintenance Report is completed.

2.2.3.3 Preliminary Engineering/Feasibility Report. Use thisreport only if changes to the FOTW are required. This is apreliminary design study that will outline what changes arerequired to attain or maintain compliance. Typically, this reportwill contain a summary of the future flows and loads to be treated(from the Capacity Analysis Report), a review of any alternativeevaluations used to select the appropriate treatment technologies,and a conceptual-level design for upgraded facilities. Aprofessional engineer sizes and plans for appropriate processchanges. The Preliminary Engineering Report is submitted as partof the permit application renewal. Some states may require finalconstruction drawings and specifications before approving thechanges, while others may issue a construction permit based solelyon the Preliminary Engineering Report.

2.2.3.4 Permit Application Forms. The environmental officeshould contact the permitting agencies to obtain the latest formsrequired for permit renewal or changes. The NPDES permitapplication forms will vary depending upon the primary agency (EPAor state) and the characteristics of the discharge. NPDESapplications usually consist of a Form 1, containing general ownerinformation, and Form 2A, containing a substantial amount of FOTWinformation. These forms require historical plant operation dataand much of the same information required for the CapacityAnalysis and Operations and Maintenance Reports. There is no fee

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required from the Federal Government, but state and local agenciesmay assess fees to process applications.

2.3 Operator Certification

2.3.1 Definition. Operator certification is a process inwhich an individual is awarded a certificate from the state waterquality regulatory agency for meeting specific criteria associatedwith the operation of wastewater treatment plants (WWTPs). Moststates require that the responsible WWTP operator possess acurrent state operator certification for the plant to meet thestate’s standard permit requirements. This certification processvaries from state to state. Most states have different levels ofcertification that depend upon plant complexity and size orindividual expertise. Certification requirements are usuallycontained in the permit and/or in state regulations.

2.3.2 Benefits of Obtaining Certification. Professional WWTPoperators should attempt to learn all that they can about theirprofession. By being certified, operators demonstrate a specificlevel of proficiency in their selected field. An operator may beable to apply for wastewater treatment positions in other statesthat have reciprocity with the state issuing an operator’s firstcertificate. As a member of the professional wastewater operatororganization, a certified operator demonstrates his or hercommitment to the profession.

2.3.3 FOTW Requirements. Many states require that the chiefoperator be certified to complete the reports that are necessaryto comply with state and Federal water pollution control laws andregulations. Some facilities are required to have a certifiedoperator on shift work when the chief operator is off shift. Insome locations, all operators may require certification for theoperation of a treatment plant. The EPA has suggested that itwould like to have all plants operated by qualified personnel;certification is a method of demonstrating an operator's level ofqualification. Failure to have the correct number and level ofcertified operators can be considered a serious complianceviolation.

2.3.4 Attaining Certification. Each state regulatory agencyhas a program for achieving its certification. It is suggestedthat operators contact the state agencies to obtain specificinformation about requirements and reciprocity programs. Althoughreciprocity exists between many states, certifications should notbe considered to be transferable. The Association of Boards of

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Certification (ABC) can help with these issues. See Appendix Cfor contact information.

2.3.5 Training for Certification. There are various methodsof obtaining training for certification. State regulatoryagencies or ABC can help. The California State University,Sacramento, has correspondence courses available that provide thebasics for most state examinations and certification processes.(The Sacramento series of O&M manuals has been adopted by themilitary as the general reference source for plant operationspersonnel.) See Appendix C for contact information.

The Water Environment Federation (WEF) is also anexcellent source for training materials. WEF has wastewatercourses both in printed and computer CD-ROM formats. See AppendixC for contact information.

State and regional professional associations in thewastewater treatment field can also help operators find localclassroom-type training. WEF can provide valuable assistance inlocating these organizations.

2.4 Current Trends in the Wastewater Industry That AffectPlant Operations. The regulatory agencies (state and/or EPA)responsible for the issuance of discharge permits are implementingmore comprehensive programs to ensure protection of the waterquality standards of the state’s streams. A comprehensivestormwater permitting program is now in place in all states. Thisprogram requires industries and municipalities to permitstormwater outfalls and to implement best management practices(BMPs) that will reduce the impact of stormwater runoff on thereceiving stream. In addition, the regulatory agencies areimplementing basinwide permitting programs designed to bringstreams that have been identified as not currently meeting waterquality standards into compliance. This program evaluates allsources of contamination (point and non-point sources); throughthe development of total maximum daily loads (TMDL) for thewatershed, the program allocates allowable discharge levels fromall sources within the drainage basin. This could mean that morerestrictive effluent limits will be placed in discharge permits.The use of TMDL in the permitting process will be prevalent whenpermits are renewed.

2.4.1 Water Quality-Based Effluent Limits. Effluent limitscontained in the NPDES permit are developed by the permit writerand are based on state water quality standards for the receiving

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stream. These effluent limits are called water quality-basedeffluent limits. Each stream in the state is classified in thewater quality standards according to its existing or potentialuses. Specific and general standards apply to eachclassification. These standards are then used in the developmentof the effluent limits for the discharger.

The inclusion of water quality-based effluent limits inthe permit is based on a review of the effluent characterizationpresented in the discharger’s permit application (EPA Form 2C).This review, conducted by the permit writer, assesses the presenceof compounds that have the potential to violate the water qualitystandards. For these compounds, permit limits will be identifiedwherever possible.

2.4.1.1 Waste Load Allocation. Most NPDES permits includelimits on oxygen demanding substances (such as CBOD and ammonia).Development of these limits is typically based on a waste loadallocation for the receiving stream. Stream modeling is used toassess the assimilative capacity of the stream based on theapplicable dissolved oxygen standard. This capacity is thenallocated among all the dischargers in the area. Generally, someportion of the stream’s capacity is reserved for futuredischargers.

Waste load allocation modeling typically consists of adesk-top effort for small discharges and a calibrated and verifiedmodel based on field measurements for larger discharges. Modelingcan be performed by the discharger or by the state agency.Regardless of who performs the modeling, the results receive adetailed review by both the state and the EPA. Typically, theseresults are put out for public comment. In many cases, the publiccomment period is concurrent with the public notice for the NPDESpermit.

2.4.1.2 Chemical-Specific Criteria. Water quality-basedeffluent limits can be based on chemical-specific criteria fromthe water quality standards (such as for metals or toxics) or ongeneral narrative criteria. Specific criteria are used in thedevelopment of effluent limits, and in many cases an allowance fordilution in the receiving stream is provided. Typically, someportion of the 7Q10 low-flow for the receiving stream is used fordilution purposes. (7Q10 is a hydrogeological determination ofthe lowest average flow over 7 consecutive days with an averagerecurrence frequency of once in 10 years.) Backgroundconcentrations in the receiving stream must also be considered in

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the dilution calculations. Where the 7Q10 low-flow is zero, thecriteria will apply at the point of discharge, prior to anydilution.

2.4.1.3 Aquatic Life Criteria. For aquatic life criteria, acuteor chronic values apply. The application of acute versus chroniccriteria is dependent on a number of items, including the useclassification and the available dilution in the receiving stream.(Generally, if the available dilution is greater than 100 to 1,then the acute criteria apply.)

2.4.1.4 General Narrative Criteria. An example of a generalnarrative criteria follows:Toxic substances should not be present in receiving waters, aftermixing, in such quantities as to be toxic to human,animal, plantor aquatic life or to interfere with the normal propagation,growth and survival of the indigenous aquatic biota.

To address this narrative criteria, most states apply awhole-effluent toxicity requirement in the permit. The whole-effluent approach to toxics control for the protection of aquaticlife involves the use of acute and/or chronic toxicity tests tomeasure the toxicity of wastewaters. The acute test assesses thelethality of the wastewater to the test organisms and is typicallyconducted for 96 hours or less. The chronic test assesses growthand reproduction in addition to lethality and is typicallyconducted over a 7-day period. Whole-effluent toxicity tests usestandardized surrogate freshwater or marine plants, invertebrates,and vertebrates. The test is run at the same dilution as isallowed for the wastewater in the receiving stream. Failure tomeet the criteria results in the need to conduct a toxicityreduction evaluation on the discharge.

2.4.1.5 Negotiation of Effluent Limits. Careful review by thedischarger of the specific basis used for the water quality-basedeffluent limits is advisable. In many cases, the basis used inthe development of the effluent limits is open to negotiation.These issues should be addressed during the permit renewalprocess.

2.4.2 Wastewater Reuse. Several states and communities arepromoting the reuse of wastewater as a beneficial way of reducingboth drinking water demands and wastewater discharge to theenvironment. The most common reuse projects involve large uses ofwater for irrigation purposes (e.g., golf courses). Other uses ofwater may include residential irrigation, fire protection,

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landscape features (ponds or fountains), and industrial supply.Generally, a project is only considered a reuse project if thereclaimed effluent replaces drinking water demand.

Groundwater discharge is sometimes referred to as"groundwater recharge" and may be considered reuse if it is usedto replenish the drinking water supply. However, contamination ofthe drinking water supply is a concern, and the discharge may haveas many disincentives as incentives. Most land applicationprojects that rely on groundwater infiltration for effluentdisposal would be considered disposal projects, not reuseprojects. Any disposal to natural surface waters will beconsidered an NPDES discharge and will be subject to allapplicable rules.

2.4.2.1 Reuse Feasibility Study. An engineering study isrequired to determine the actual water usage for a given reuseproject. For example, an irrigator will not need water in wetperiods or winter. The FOTW may therefore need to dispose of allof its effluent for extended periods of time. The permitrequirements need to be flexible to accommodate such seasonaleffects. The objective of the engineering study is to determine aconceptual reuse system, including customers, available capacity,the size of the pipeline, pumps, and storage. This study is not adesign-level project. Further design and permitting is requiredto implement a project.

2.4.2.2 Reuse Treatment Facilities. An FOTW may need additionaltreatment capability to provide reuse-quality water. If there isa possibility of public contact with the water, then the effluentmust have high-level disinfection (<20 MPN [most probable number]per 100 mL). Filtration before disinfection or discharge to anirrigation system would also be likely. If only a portion of theeffluent flow is used for reuse, then these additional facilitieswould need to be sized accordingly and would treat only a side-stream. An engineering feasibility study would need to determinethe size and layout of these treatment facilities.

2.4.3 40 CFR Part 503 Sludge Regulations. Biosolids havebeneficial plant nutrients and soil-conditioning properties.However, biosolids may also contain heavy metals, bacteria,viruses, protozoa, parasites, and other microorganisms that cancause disease. If improperly treated and applied, they may alsoattract nuisance vectors, such as insects and rodents. The EPAactively promotes management practices that provide for thebeneficial reuse of biosolids while maintaining or improving

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environmental quality and protecting human health. However, whilethe Part 503 regulations encourage the beneficial reuse ofbiosolids, they do not mandate it; traditional disposal methodssuch as landfilling may still be selected.

The use and disposal of biosolids, including domesticseptage, are regulated under 40 CFR Part 503. This regulation,promulgated on February 19, 1993, was issued under the authorityof the Clean Water Act, as amended in 1977, and the 1976 ResourceConservation and Recovery Act. For most sludges, the newregulation replaces 40 CFR Part 257—the original regulationgoverning the use and disposal of sludge that has been in effectsince 1979. Sludges generated at an industrial facility duringthe treatment of domestic wastewater, commingled with industrialwastewater in an industrial wastewater treatment facility, arestill covered under 40 CFR Part 257 if the solids are applied tothe land. For most FOTWs, however, 40 CFR Part 503 is theapplicable regulation.

For additional information on the Part 503 regulations,refer to EPA/G25/R-92-013, Environmental Regulations andTechnology: Control of Pathogens and Vector Attraction in Sludge(Including Domestic Septage) Under 40 CFR Part 503.

2.4.3.1 Solids Definitions. The Part 503 regulationspromulgated the word “sludge” to describe a variety of solidsresiduals from wastewater treatment processes. The wastewatertreatment industry and regulatory agencies have recently tried tominimize the use of the word “sludge” because the term is toogeneral and its negative connotations do not accurately reflectthe industry’s goal: to promote the beneficial reuse of properlytreated wastewater solids as useful soil amendments foragricultural users and the general population. In keeping withcurrent industry practices, this document avoids the word “sludge”except when directly referred to in Part 503 regulations or awidely accepted process name such as the “activated sludgeprocess.” Figure 1 shows a secondary wastewater treatment plantand identifies the terminology used by industry and this documentto replace the word “sludge.”

The primary solids referred to in Figure 1 are thosederived from primary treatment processes. Solids drawn from thesecondary treatment system are referred to as “waste activatedsludge” or “biosolids.” The word “biosolids” refers to theresidual treatment bacteria and inert solids contained in thebiological treatment process. Solids that have undergone

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treatment for beneficial reuse are generally referred to as“residual solids” or can be classified according to their level oftreatment, such as “Class A Solids.” In some cases, treatmentfacilities do not further treat primary or secondary solids anddispose of these in a permitted landfill; in this case, theresiduals are referred to as “sludge,” meaning the product has notreceived treatment to reduce pathogens or vector attraction. Thephrase “other residual solids” refers to the dense, grit-likesolids that accumulate in process tanks and are removed when thetanks are periodically emptied and cleaned.

2.4.3.2 Protection of Public Health and the Environment. In thejudgment of the Administrator of EPA, Part 503 protects publichealth and the environment through requirements designed to reducethe potential for contact with the disease-bearing microorganisms(pathogens) and heavy metals in biosolids applied to the land orplaced on a surface disposal site. These requirements are dividedinto the following categories:

a) Requirements designed to control and reducepathogens in solids

b) Requirements designed to reduce the ability of thesolids to attract vectors (rodents, birds, insects, and otherliving organisms that can transport solids pathogens away from theland application or surface disposal site)

c) Requirements designed to limit the amount of heavymetals in solids applied to land or placed on a surface disposalsite

Subpart D of Part 503 includes both performance- andtechnology-based requirements that aim to reduce pathogens andvector attraction. It is designed to provide a more flexibleapproach than Part 257, which required solids to be treated byspecific listed or approved treatment technologies. UnderPart 503, treatment works may continue to use the same processesthey used under Part 257, but they now also have the freedom tomodify conditions and combine processes with each other, as longas the treated solids meet the applicable requirements.

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Figure 1Definitions of Solids

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2.4.3.3 Applicability of the Requirements [503.15]. Part 503.15covers the applicability of the pathogen and vector attractionreduction requirements. The Subpart D requirements apply tosolids (both bulk solids and solids that are sold or given away ina bag or other container for application to the land) and domesticseptage applied to the land or placed on a surface disposal site.The regulated community includes persons who generate or preparesolids for application to the land, as well as those who apply itto the land, including anyone who:

a) Generates solids that are land-applied or placed ona surface disposal site

b) Derives a material from solids

c) Applies solids to the land

d) Owns or operates a surface disposal site

2.4.3.4 Requirements for Land Application or Disposal. Solidscannot be applied to land or placed on a surface disposal siteunless they have met the two basic types of requirements inSubpart D: pathogen and vector attraction reduction requirements.These two types of requirements are separated in Part 503 (theywere combined in Part 257) which allows flexibility in how theyare achieved. Compliance with the two types of requirements mustbe demonstrated separately. Therefore, demonstration that arequirement for reduced vector attraction has been met does notimply that a pathogen reduction requirement also has been met, andvice versa.

2.4.3.5 Pathogen Reduction Requirements. Sewage Sludge[503.32(a) and (b)]. The pathogen reduction requirements forsewage sludge are divided into two categories: Class A andClass B. These requirements use a combination of technologicaland microbiological requirements to ensure reduction of pathogens.

The implicit goal of the Class A requirements is toreduce the pathogens in sewage sludge (including enteric viruses,pathogenic bacteria, and viable helminth ova) to below detectablelevels. The implicit goal of the Class B requirements is toensure that pathogens have been reduced to levels that areunlikely to pose a threat to public health and the environmentunder the specific use conditions. For Class B solids that areapplied to land, site restrictions are imposed to minimize thepotential for human and animal contact for a period of time

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following land application, until environmental factors havefurther reduced pathogens. Class B solids cannot be sold or givenaway in bags or other containers for application to the land.There are no site restrictions for Class A solids.

Domestic Septage [503.32(c)]. Domestic septage is aform of sewage sludge. The requirements for domestic septage varydepending on how it is used or disposed. Domestic septage appliedto a public contact site, lawn, or home garden must meet the samerequirements as other forms of sewage sludge. Separate, lesscomplicated requirements for pathogen reduction, apply to domesticseptage applied to agricultural land, forests, or reclamationsites. These requirements include site restrictions to reduce thepotential for human contact and to allow for environmentalattenuation, or pH adjustment with site restrictions only onharvesting crops. No pathogen requirements apply if domesticseptage is placed on a surface disposal site.

2.4.3.6 Vector Attraction Reduction Requirements [503.33].Subpart D specifies 12 options to demonstrate reduced vectorattraction. Eight of the options apply to sewage sludges thathave been treated in some way to reduce vector attraction (e.g.,aerobic or anaerobic digestion, composting, alkali addition, anddrying). These options consist of operating conditions or teststo demonstrate that vector attraction has been reduced in thetreated solids. Three options cover methods for injection orincorporating solids into the soil to reduce vector attraction.

One option is a requirement to demonstrate reducedvector attraction in domestic septage through elevated pH. Thisoption applies only to domestic septage.

2.4.3.7 Frequency of Monitoring

a) Sewage Sludge [503.16(a) and 503.26(a)]. TheClass A and Class B pathogen requirements and the first eightvector attraction reduction options (the treatment-relatedmethods) all involve some form of monitoring. The minimumfrequency of monitoring for these requirements is given in Part503.16(a) for land application and Part 503.26(a) for surfacedisposal. The frequency depends on the amount of solids used ordisposed of annually. The larger the amount used or disposed of,the more frequently monitoring is required.

b) Domestic Septage [503.16(b) and 503.26(b)]. One ofthe options that can be used for demonstrating both pathogen

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reduction and vector attraction reduction in domestic septage isto elevate pH to >12 for 30 minutes. When this option is used,each container of domestic septage (e.g., each tank truck load)applied to the land or placed on a surface disposal site must bemonitored for pH.

2.4.3.8 Recordkeeping Requirements [503.17 and 503.27].Recordkeeping requirements are covered in Part 503.17 for landapplication and Part 503.27 for surface disposal. Records arerequired for both sewage sludge and domestic septage. All recordsmust be retained for 5 years except when the cumulative pollutantloading rates in Part 503 Subpart B (Land Application) are used.In that case, certain records must be kept indefinitely. Somerecords must be reported to the permitting authority.

a) Land Application. Records must be kept to ensurethat the solids meet the applicable pollutant limits, managementpractices, one of the pathogen requirements, one of the vectorattraction reduction requirements and, where applicable, the siterestrictions associated with land application of Class Bbiosolids. When bulk solids are applied to land, both the personpreparing the solids for land application and the person applyingthem must keep records. The person applying solids that are soldor given away does not have to keep records.

b) Surface Disposal. When solids are placed on asurface disposal site, both the person preparing the solids andthe owner/operator of the surface disposal site must keep records.In the case of domestic septage applied to agricultural land,forest, or a reclamation site or placed on a surface disposalsite, the person applying the domestic septage and theowner/operator of the surface disposal site may be subject topathogen-related recordkeeping requirements, depending on whichvector attraction reduction option was used.

c) Certification Statement. In every case,recordkeeping involves signing a certification statement that therequirement has been met. Parts 503.17 and 503.37 of theregulation contain the required certification language.

2.4.3.9 Reporting Requirements for Sewage Solids [503.18 and503.28]. Reporting requirements for these solids are found inPart 503.18 for land application and Part 503.28 for surfacedisposal. These requirements apply to Class I solids managementfacilities and to publicly owned treatment works and FOTWs with adesign flow rate equal to or greater than 1 mgd and/or that serve

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10,000 or more people. These facilities must submit to thepermitting authority the records they are required to keep as“preparers” of biosolids and/or as the owner/operators of surfacedisposal sites on February 19 of each year. There are noreporting requirements associated with the use or disposal ofdomestic septage.

2.4.3.10 Permits and Direct Enforceability [503.3]

a) Permits. Under Part 503.3(a), the requirements inPart 503 may be implemented through: (1) permits issued totreatment works treating domestic sewage by EPA or by states withan EPA-approved solids management program, and (2) by permitsissued under Subtitle C of the Solid Waste Disposal Act; Part C ofthe Safe Drinking Water Act; the Marine Protection, Research, andSanctuaries Act of 1972; or the Clean Air Act. Treatment workstreating domestic sewage should submit a permit application to theapproved state program, or, if there is no such program, to theEPA Regional Sludge Coordinator.

b) Direct Enforceability. Under Part 503.3(b), therequirements of Part 503 automatically apply and are directlyenforceable even when no permit has been issued.

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Section 3: SEPTIC TANKS

3.1 Description. Septic tank systems are used to treat anddispose of wastewater from individual homes and buildings where itis not feasible to provide a community wastewater collection andtreatment system. All components of the septic tank system areunderground. Figure 2 depicts a standard two-compartment septictank system.

3.1.1 System Components. The individual home or buildingdischarges through a pipeline to the septic tank, which in turndischarges to the effluent leaching system. Where groundwaterlevels are high, the elevation may be insufficient for gravityflow and pumps may be required on either side of the septic tank.Pumps located before the septic tank require diligent maintenancebecause they directly receive untreated wastewater. Refer tomanufacturer’s recommendations for maintenance of these pumps.

3.1.1.1 Tank. The septic tank is an underground, watertightconcrete or fiberglass receptacle that typically has a liquiddepth of at least 42 inches (1 m). Inlets and outlets are locatedat opposite ends of the tank. The inlets generally have invertelevations 1 to 3 inches (3 to 8 cm) above the liquid level of thetank. The outlets generally have a vented tee so that the intaketo the outlet device is below the liquid level. A system may havetwo or more septic tanks placed in a series.

3.1.1.2 Effluent Leaching Systems. Wastewater dischargesthrough a pipe from the septic tank to the underground effluentleaching system. The effluent leaching system consists of adistribution box or header pipe and a drain field. The drainfield is a system of open-jointed or perforated piping that allowsthe wastewater effluent to be distributed gradually into the soil.Typically, all portions of the effluent leaching system areinstalled below the elevation of undisturbed native soil. A moundsystem is used in locations where the depth is insufficient forthe effluent leaching system because of high groundwater levels,insufficient permeable soil, or other conditions. For moundsystems, all or part of the leaching system is located above theelevation of undisturbed native soil. Mound systems require a pumpto deliver the effluent to the elevated leaching system. Electriccontrols outside the dosing chamber and a power supply may berequired to operate the pump.

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Figure 2Typical Two-Compartment Septic Tank

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3.1.2 System Operation Principles. Wastewater flows out ofthe building through a pipe into the septic tank. In the tank,bacteria attack and digest organic matter by anaerobic digestion.The wastewater itself provides the bacteria for this process. Theanaerobic digestion process changes the waste into gas, biosolids(residual organic and inorganic material), and treated effluent.The gas escapes into the air, the treated effluent is dischargedto the leaching system, and the residual solids remain in thetank. The solids should be pumped out of the tank periodically.The treated effluent is discharged into the soil through theperforated or open-jointed pipes in the drain field. Soilbacteria destroy remaining organic material in the effluent.

3.2 Septic Tank System O&M. The primary O&M requirement forthe septic tank system is periodic removal of settleable solids.In addition, take preventative care of the system by monitoringwaste disposed to the system and ensuring that trees or shrubs arenot planted over any of the system components. It is notnecessary to add yeast or bacteria to the system as a maintenanceprocedure. As long as human and kitchen wastes are beingdischarged to the system, there will be sufficient bacteria in thetank for treatment.

3.2.1 Inspecting the Septic Tank. Check the septic tank every3 to 5 years to determine if solids need to be removed. Check thetank once a year if garbage disposals discharge to the tank.

Caution: Exercise extreme care when inspecting theseptic tank. Never inspect a septic tank alone or enter a tank.Toxic gases are produced by the natural treatment processes inseptic tanks and these gases can kill in minutes. Details onconfined space entry requirements are found in the SacramentoSeries Operation of Wastewater Treatment Plants, Volume 2,Chapter 14.

3.2.1.1 Measuring Solids and Scum Inside the Tank. Thefollowing information comes from Pipeline: Maintaining YourSeptic System—A Guide for Homeowners, National Small FlowsClearinghouse, 1995.

There are two frequently used methods for measuring thesolids and scum layers inside your tank. The contractor may use ahollow clear plastic tube that is pushed through the differentlayers to the bottom of the tank. When brought back up, the tuberetains a sample showing a cross-section of the inside of thetank. The layers can also be measured using a long stick. To

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measure the scum layer using a stick, a 3-inch (8 cm) piece ofwood is attached across the end of the stick to form a "foot," andthe stick is pushed down through the scum to the liquid layer.When the stick is moved up, the foot meets resistance on thebottom of the scum layer, and the contractor marks the stick atthe top of the layer to measure the total thickness. As a generalguideline, if the scum layer is within 3 inches (8 cm) of thebottom of the inlet baffle, the tank should be pumped.

The solids layer is measured by wrapping cloth aroundthe bottom of the stick and lowering it to the bottom of the tank.Insert the stick either through a hole in the scum layer orthrough the baffle or tee, if possible, to avoid getting scum onthe cloth. The solids depth can be estimated by the length ofsolids sticking to the cloth. If the solids depth is equal toone-third or more of the liquid depth, the tank should be pumped.

3.2.2 Removal of Settleable Solids. Clean the tank wheneverthe bottom of the floating scum layer is within 8 inches (20 cm)of the bottom of the outlet device. Table 1 shows the estimatedtank pumping frequencies, based on tank size and household size.

Table 1Estimated Septic Tank Pumping Frequencies in Years(1)

Tank SizeHousehold Size(number of people)

(gallons) 1 2 3 4 5 6500 5.8 2.6 1.5 1.0 0.7 0.4750 9.1 4.2 2.6 1.8 1.3 1.0900 11.0 5.2 3.3 2.3 1.7 1.31,000 12.4 5.9 3.7 2.6 2.0 1.51,250 15.6 7.5 4.8 3.4 2.6 2.01,500 18.9 9.1 5.9 4.2 3.3 2.61,750 22.1 10.7 6.9 5.0 3.9 3.12,000 25.4 12.4 8.0 5.9 4.5 3.72,250 28.6 14.0 9.1 6.7 5.2 4.22,500 31.9 15.6 10.2 7.5 5.9 4.8

(1) These figures assume no garbage disposal is in use.Source: Pennsylvania State University Cooperative ExtensionService, as reprinted in Pipeline: Maintaining Your Septic System—A Guide for Homeowners, National Small Flows Clearinghouse, 1995

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When cleaning the tank, remove all contents, includingscum, liquid, and solids. Use only the access ports on the tankfor cleaning; do not pump out the tank through the distributionbox. Do not use toxic or hazardous chemicals for cleaning thetank and do not use organic chemical solvents or petroleumproducts for degreasing or declogging the system. These chemicalsand products are potentially harmful to the system and to thegroundwater in the vicinity of the system.

3.2.3 Monitoring Waste Discharged to System. Because theseptic tank treatment system is a biological process, it isparticularly important that toxic or hazardous chemicals are notdischarged into it. These chemicals would kill the bacteria usedfor treatment of the wastewater. Discharge of industrialwastewater to septic tanks violates the underground injectionprovisions of the SDWA. In addition, grease and non-biodegradableproducts should not be discharged into the system. The system isnot designed to treat these products and they can cause cloggingin the system components. Household cleaners such as bleach,disinfectants, and drain and toilet bowl cleaners should be usedin moderation and only in accordance with product labels. Overuseof these products can harm the septic tank system.

3.2.4 Water Conservation. Water conservation is critical forproper operation of the drain field. Continual saturation of thesoil in the drain field can significantly reduce the ability ofthe soil to naturally remove toxins, bacteria, viruses, and otherpollutants from the wastewater. In addition to conserving waterdischarged to the septic tank and drain field, try to restrictwater from roof drains, sump pumps, and other sources fromdraining into the area of the drain field.

3.2.5 Vegetation Over System Components. Do not plant treesor shrubbery over any of the system components. If a tree or bushhas a strong root system, the roots can choke the drain fieldand/or get into the septic tank. Roots in the septic tank canreduce its capacity and block the inlet or outlet.

3.3 Leachate System O&M. The only remedy for a leachatesystem that is not functioning is replacement. There are noconclusive data to support the premise that enzymes and chemicaltreatment can revitalize a drain field. To construct a new drainfield on top of an existing field, dig trenches parallel to theexisting drain field pipes or widen the existing trenches.

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3.4 Septic Tank System Failures. Several warning signs canindicate that a septic tank system is failing and that more thancleaning of the system is necessary:

a) Obnoxious odors in the area of the system or insidethe building

b) Soft ground or low spots in the area of the system

c) Grass growing faster or greener in the area of thesystem

d) Gurgling sounds in the plumbing or plumbing backups

e) Sluggishness in the toilet when flushed

f) Plumbing backups

g) Tests showing the presence of bacteria in nearbywell water

Table 2 shows possible causes of septic tank systemfailures and suggests remedial procedures.

Table 2Maintenance Checklist for Septic Tank System Failures

Possible Causes of Failure Possible Remedial ProceduresUnderdesign

Tank size insufficient for wastewater flow quantity and/or characteristics

Replace septic tank or addadditional septic tank(s) inparallel.

Drain field too small Enlarge drain field. Reducewater consumption.

Faulty drain field installation

Plugged pipes

Insufficient stone in trenches

Uneven grades

For plugged pipes, insufficientstone, and uneven grades,install a new drain field on topof existing field.

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Table 2 (Continued)Maintenance Checklist for Septic Tank System Failures

Possible Causes of Failure Possible Remedial ProceduresPoor soil conditions

High groundwater Improve surface drainage;install curtain drains; elevatefield; and/or reduce waterconsumption.

Insufficient distance below drain field to bedrock

Relatively impervious soils

Elevate drain field and/orreduce water consumption.

Elevate drain field and/orreduce water consumption.

Overload

Excessive wastewater loading Increase tank size or reducewater consumption.

Poor stormwater drainage away from system

Leaking plumbing fixtures

Wastewater flow quantity and/or characteristics greaterthan anticipated in design dueto changes in use of building,garbage grinders, etc.

Improve surface drainage.

Repair plumbing fixtures.

Remove garbage grinders;increase drain field.

Lack of Tank Maintenance

Septic tanks not pumped out atsufficient intervals, causing solids to be discharged to drain field

Pump out tank; construct newdrain field on top of existingdrain field; relieve drain fieldby draining into a pit andpumping out and let field restfor a month.

Source: Adapted from Rein Laak's Wastewater Engineering Design forUnsewered Areas, Lancaster, Pennsylvania: Technomic PublishingCo., Inc., 1986

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Section 4: GREASE TRAPS

4.1 Description. Food-service operations typically usegrease traps to prevent excessive discharge of grease and oilinto the wastewater collection and treatment system. If greasetraps are not properly maintained, slug loads of grease willinterfere with the performance of both the collection andtreatment system. Grease traps are usually located outside thefood-service establishment in an underground tank with ground-level access. Sometimes under-sink systems are also used forgrease traps; however, these are not recommended because theygenerally do not provide adequate grease removal. Where under-sink models are used, proper maintenance is especially criticalbecause of the higher potential for release of slug loads ofgrease into the wastewater system.

4.1.1 Configuration. Grease traps usually consist of anunderground, watertight concrete tank with inlet and outletpiping. The outlet pipe has a tee that allows the internaldischarge to be located within 12 inches (0.3 m) of the tankbottom. The size of the grease trap depends on the anticipatedflow rate, water temperature, and grease concentration. Ingeneral, grease traps range from a minimum capacity of750 gallons (2.8 m3) to a maximum capacity of 1,250 gallons(4.7 m3). Where a capacity of more than 1,250 gallons (4.7 m3) isrequired, two or more grease traps may be placed in a series.Access to the tank is typically through one or two manhole ringsand covers.

4.1.2 Location. Grease traps should be located outside food-service buildings in an accessible location for inspection andmaintenance. The traps are installed in the waste line betweenthe sink drains and kitchen fixtures and the wastewatercollection system.

4.1.3 Discharges to Grease Traps. Grease traps do notperform effectively if they receive discharges with elevatedtemperatures or high solids concentrations. Grease traps shouldnot receive discharges from garbage grinders or produce-preparation sinks. Discharges from mechanical dishwashers arealso not recommended. However, the preflush/prescraping sinksthat serve mechanical dishwashers may be connected to the greasetrap, provided no garbage grinders are used at these sinks.

4.2 Maintenance Procedures. The critical maintenanceprocedure for all grease traps is periodic removal of accumulated

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waste. If the responsibility and procedures for cleaning greasetraps are not clearly identified and implemented, the traps areineffective. It is recommended that waste be pumped out of thegrease traps rather than dissolved with solvents. Grease andsolvents may have a negative impact on the wastewater collectionand treatment system. Recovered oil and grease from food-serviceoperations can typically be sold to a local rendering company.Other types of oils can often be reclaimed by recyclers. Ifproper maintenance cannot be maintained, consideration should begiven to removing the grease trap and having the user separatethe grease before discharging wastewater to the sanitary system.

4.2.1 Pump-Out Frequency. The recommended pump-out frequencyranges from every 2 weeks to every 3 months, depending on thewaste characteristics of the establishment and the size of thegrease trap. The necessary pump-out frequency can be determinedby checking the grease retention capacity in the grease trap.Grease and accumulated wastes should be removed as often asnecessary to maintain as least 50 percent of the grease retentioncapacity.

4.2.2 Maintenance Specific to Manufactured Grease-RemovalSystems. In addition to periodically removing the waste, reviewand implement the manufacturer’s recommended maintenanceprocedures for all grease-removal systems.

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Section 5: OIL/WATER SEPARATORS

5.1 Oil/Water Separators. Oil/water separators are devicescommonly used to separate oily waste products from wastewaterstreams. They are typically installed in industrial andmaintenance areas to receive and separate oils at lowconcentrations from wastewater generated during industrialprocesses such as maintaining and washing aircrafts and vehicles.The number of separators currently owned and operated by themilitary is in the thousands. A large installation may have asmany as 150 units. In recent years, it has become clear thatmany of the military’s separators are not performing asanticipated. Inadequacies have resulted from poor design,improper selection of pre-manufactured units, misuse bydischarging inappropriate wastewaters or excessive quantities,and lack of monitoring and maintenance.

5.2 Types of Oil/Water Separators. There are threepredominant types of oil/water separators: conventional gravityseparators, corrugated plate gravity separators, and flotationseparators. The overwhelming majority of oil/water separatorsused are conventional gravity separators. Most units, regardlessof the type, are purchased as proprietary equipment from vendors.Accordingly, the manufacturer’s recommended O&M procedures shouldbe consulted and followed. A brief description of the main typesof oil/water separators follows.

The primary types of oil/water separators described inthis section are intended for the removal of free and de-emulsified oils and greases, usually as a pretreatment method.There are numerous other polishing oil/water separators marketedfor removal of trace quantities of oil and grease. These devicesinclude coalescing filters, oleophilic filters, and adsorptiondevices. Operators should consult the manufacturer’s proprietaryoperations and maintenance guidance for these devices.

5.2.1 Gravity Separators. The process relies on thedifferent densities of oil, water, and solids for successfuloperation. The wastewater is fed to a vessel sized to provide aquiescent zone of sufficient retention time to allow the oil tofloat to the top and the solids to settle to the bottom. Gravityoil/water separators come in two configurations: conventionalgravity separators such as those designed in accordance withguidelines established by the American Petroleum Institute (API)and corrugated plate interceptors (CPIs).

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5.2.1.1 Conventional Gravity-Type Separators. Conventionalgravity separators are typically rectangular in-ground or above-ground tanks with maximum widths of 20 feet (6 m). A diagram ofa typical conventional gravity separator is presented inFigure 3. Influent and effluent channels are normally located onopposite ends of the separator. The influent typically passes aninlet section that contains a slotted baffle to distributeinfluent evenly throughout the depth of the separator. For unitswithout sludge collectors, there may also be a bottom baffle inthe separator; this retains settled solids in the front part ofthe separator to reduce cleaning requirements. Other separatorsmay have automatic sludge removal equipment that will rakeaccumulated sludge to a sludge hopper where it can be pumped fromthe tank periodically.

In either case, the sludge level should be monitoredroutinely, and sludge should be removed when it occupies 10percent or more of the separator volume. All conventionalgravity separators have a surface baffle at the outlet end toretain floating oil and grease. The grease is removed by pumpingor by activating a rotary drum or slotted pipe that allows thesurface material to drain to a drum or oil holding tank. Thedepth of the surface oil layer should be checked regularly, andsurface skimming should be conducted routinely. Experiencegained from operating a conventional gravity separator in aspecific application will indicate the required intervals forchecking and skimming the oil layer. For example, although theoil layer might need to be checked and skimmed daily, thisinterval could range from several times per day to several timesper month, depending on the rate of oil accumulation on theseparator surface.

One criterion to use is that the oil layer should bemonitored and skimmed as often as is necessary to prevent anexcess amount of oil from being flushed through the separator byan unexpected hydraulic surge (e.g., rainfall). Thus, thefrequency may also depend on the sensitivity of downstreamprocesses to increased oil loading. The frequency will have tobe determined by experience but it likely will be such that thefloating oil layer does not exceed about 2 inches (5 cm) (someoperators prefer that there be no floating oil layer on theseparator).

5.2.1.2 Corrugated Plate Interceptors. CPIs are typicallysupplied by vendors and are based on proprietary designs. A CPI

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Figure 3Conventional Gravity Separator

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Figure 4Process Schematic of CPI Separator

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consists of a tank containing a number of parallel corrugatedplates mounted from 0.8 to 1.6 inches (2 to 4 cm) apart andinclined at an angle to the horizontal. A diagram of a typicalCPI is presented in Figure 4. Wastewater may flow eitherdownward or upward between the plates; in the configurationshown, wastewater flows downward through the plates. As thishappens, the oil droplets float upward and collect on theunderside of adjacent plates where they coalesce. The coalescedoil droplets move up the plates and are retained in the separatorto form a floating layer that is skimmed from the surface of thetank. Settled solids from the wastewater collect on the top sideof adjacent plates, migrating down the plates and dropping intothe bottom of the CPI vessel. In the diagram shown, treated waterflows down through the plates, and over a weir into an effluentflume. Some manufacturers use different configurations than theone shown.

CPI separators are smaller and easier to cover forcontrolling atmospheric emissions, and they may be less expensivethan API-type separators. In practice, however, the smaller sizehas sometimes been a disadvantage since it may not providesufficient volume to accommodate slugs of oil and it may notprovide sufficient detention time for breaking emulsions.In some cases, the plate packs have become severely fouled. CPIsare usually drained and hosed down routinely to clean the plates.Operating experience over time will dictate how often thisoccurs, but a minimum interval of every 6 months is appropriate.

5.2.2 Dissolved Air Flotation (DAF). DAF is commonly used toremove oil, grease, and suspended solids from industrialwastewaters. Typically, gravity oil/water separators are used infront of flotation units to remove the major fraction of free orfloating oils, so flotation units are usually consideredpolishing units.

In the flotation process, small gas bubbles risingthrough the wastewater adhere to solids particles and oilglobules, causing them to float to the surface where they areskimmed off. A diagram of a typical flotation system ispresented in Figure 5. The air bubbles can be added to thewastewater by a variety of means. Diffused air flotation andinduced air flotation are the two most common types of DAF units.Both types incorporate a flotation vessel with a baffle to retainfloated oil, an oil-skimming mechanism, and sometimes a bottom-scraping mechanism to remove very heavy particles that do notfloat.

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Figure 5Process Schematic of Dissolved Air Flotation

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Significant mechanical equipment is associated withthese systems and should be maintained according tomanufacturers’ directions. Flotation vessel surface skimminggenerally is continuous, but settled sludge must be drawn offmanually. The drawoff frequency will have to be determined byexperience but could range from once daily to twice monthly, withweekly being a reasonable starting point.

5.3 Problems with Oil/Water Separator Applications.Oil/water separators are used to remove small amounts of oil andother petroleum products from wastewaters prior to furthertreatment. The military has historically purchased and installedgravity oil/water separators under the assumption that it hasonly an oil/water separation problem to solve. However, the mostcommon military applications seldom involve simple oil-and-watermixtures.

Waste streams generated from military applicationsfrequently contain significant quantities of dirt, cleaning aids(detergents, solvents), fuels, floatable debris, and variousother items common to military equipment and activities.Oil/water separators are not designed to separate these otherproducts. An oil/water separator must not be used as a catch-allfor wastes generated from any maintenance activity, andmaintenance personnel need to be made aware of this fact.Improper use can result in illegal discharges of hazardoussubstances to stormwater systems or WWTPs. Even when dischargesare not illegal, misuse of these systems can upset treatmentplants, cause discharge permit violations, increase sludgedisposal costs, and eliminate beneficial reuse of wastewater orsludge.

The following factors directly affect the efficiency,use, and management of oil/water separators: frequency andintensity of influent flow, design capacity, emulsifying agents,periodic maintenance practices, type of separator system, andother contaminants contained in the waste stream. Installationpersonnel should be familiar with these factors so they properlydesign, select, install, operate, and maintain these systems.A separator that is being used improperly should be reported tothe environmental office.

5.3.1 Frequency and Intensity of Flow. The longer theresidence time of the waste stream in the oil/water separator,the more efficient it will be at separating oil. Contaminatedwater enters a receiving chamber of the separator where the flow

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velocity of the wastewater is reduced, thereby allowing heavysolids to settle while larger oil droplets float to the top ofthe compartment. Further separation continues in a separationchamber where smaller droplets of oil separate from the water andjoin the larger droplets previously separated. The oil layerthat has accumulated on the top of the water spills over an oilskimmer into a holding area; the wastewater then flows, or ispumped, to the stormwater or sanitary sewer system.

A longer separation time increases the efficiency ofthe oil/water separator by allowing a greater amount of oil torise to the top of the wastewater. Therefore, restricting thewastewater to design flow rates will improve the efficiency ofthe separator.

5.3.2 Design Capacity. An oil/water separator has a finitecapacity for storing oils and sludges accumulated during itsoperation. Quite often the oil/water separator holdingcompartments can become saturated or full of oils and sludges,allowing contamination to flow freely into the wastewatereffluent exiting the separator system. Ensuring that theseparator capacity meets the needs of the process will aidseparation efficiency.

5.3.3 Emulsifying Agents. Detergents and soaps designed toremove oily grime from dirty weapon systems, vehicles, or othercomponents can adversely affect oil/water separator operation.These agents are designed to increase solvency of oily grime inwater. Hence, the oil droplets take longer to separate fromwater, reducing separation efficiency. Overzealous use ofdetergents can degrade efficiency by completely emulsifying oilin the wastewater stream, thus allowing the oil to pass throughan oil/water separator unaffected.

5.3.4 Periodic Maintenance Practices. Sludges and oils thatare not periodically pumped from separator holding tanks canrender the separator inoperative. Additionally, leaks fromoil/water separators can result in environmental pollution thatcould require investigative studies and extensive cleanup.Regular equipment inspections and a preventive maintenance plancan prevent contaminated discharges from the oil/water separatorsystem. Depending on the wastewater characteristics (e.g., lowpH), what material the separator is made of, and the age of thefacility, visual equipment inspections should be performed fromonce per week to once per month. More rigorous inspectionsshould be conducted two to four times per year. Inspections

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should focus on areas below the water line; equipmentconstruction joints; piping connections and interfaces; and otherareas prone to wear, spills, or leaks. See par. 5.5 for moredetail.

5.3.5 Type of Oil/Water Separator System. An oil/waterseparator designed and installed to a past mission requirementmay not be suitable for current maintenance operations. Forexample, a wash rack with an oil/water separator designed tocapture contaminants from a small fighter aircraft will nothandle larger wastewater volumes from a larger aircraft.Additionally, changes in mission can affect the effluentcharacteristics of the wastewater being discharged to anoil/water separator (i.e., wastewater with solvents or emulsionsversus free floating oil). Thus, as installation missionsevolve, treatment system design criteria must be reviewed toconfirm continued suitability.

Mission conversions can necessitate modifyingstormwater/wastewater drainage systems. Stormwater from areasthat are uncontaminated under one mission may be contaminatedunder another mission, and vice versa. Oil/water separators thatdo not have a stormwater diversion system can suffer from reducedremovals from the hydraulic loading of stormwater that does notneed to be treated. Thus, separator collection systems also mustbe reviewed for excessive stormwater flows.

5.3.6 Contaminants in Wastewater Stream. Particulate heavymetals and solids in the wastewater will settle into the sludgeat the bottom of the oil/water separator receiving compartments.The sludge could be regulated as a hazardous waste if levelsexceed RCRA or state hazardous waste levels. Solvents or fuelsmay also be retained in oil/water separator sludge.

5.4 Evaluation of Need for Oil/Water Separators.Unauthorized discharges of industrial pollutants, as well asinadequate O&M of oil/water separators, can create seriousliability and noncompliance. If an oil/water separator is notneeded to meet pretreatment or discharge permit limits, or toallow for beneficial reuse, it should probably be removed toeliminate the management responsibility and the potentialliability associated with it (Figure 6). Although this is anenvironmental issue, operators can assist by knowing what isdischarged to separators, educating others whose activities aregenerating the wastewater, and alerting their environmental staffof any problems. Because of the potential and significant effect

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on oil/water separator O&M, it is especially important to ensurethat only wastewater associated with vehicle and equipmentmaintenance activities are discharged to oil/water separators.This wastewater typically contains oil and grease but has arelatively small amount of solids. (By comparison, exteriorwashing of vehicles and equipment, particularly after fieldtraining exercises, can discharge large quantities of solids.Consequently, at many installations, central vehicle wash racksare specifically provided for exterior washing and this is notpermitted at maintenance facilities.) Oil/water separator usersshould assist environmental staff with the tasks detailed below.

In addition, operators can assist environmentalmanagement staff in evaluating the need for and effectiveness ofexisting oil/water separators with the goal of consolidating oreliminating ineffective units. Issues to consider in evaluatingthe need for oil/water separators are discussed below.

a) The working area for outside maintenanceinstallations should be minimized to reduce the volume ofcontaminated runoff requiring treatment. Using high-pressurewater and/or detergents to clean up the work area increasesemulsification and inhibits gravity oil/water separation and istherefore not recommended.

b) Use of dry absorbents should be considered tominimize the amount of oils reaching installation sewers. Dryabsorbents may be collected and disposed of with solid wastematerials. Evaluate the flash point of spent absorbent forpossible hazardous waste designation under RCRA guidelines.

c) Point source controls should be investigated toeliminate or reduce the wastewater volume and contaminantconcentrations. For example, segregate used oils and solventsfor disposal or reuse rather than allowing them to enter thewastewater stream. Implementing point source controls may bemore economical than providing a wastewater treatment system.Also, consider point source control techniques, such as processchange or modification, material recovery, wastewatersegregation, and water reuse.

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Figure 6Decision Tree for Pretreatment of Oily Waste

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d) Making process changes may eliminate the perceivedneed for an oil/water separator. Is the floor drain in themaintenance bay necessary? The drain should be protected againsthazardous substance spills if there is a potential for spills inthat area. Can a dry process replace a wet process? Thisapproach would completely eliminate a wastewater stream. Anoil/water separator should not be installed to capture spills. Aholding tank can accomplish this.

e) The formation of oil emulsions should be minimizedand emulsions should be segregated for special treatment wheneverpossible. Emulsions are usually complex, and bench scale orpilot scale testing is generally necessary to determine aneffective method for emulsion breaking. For guidance inemulsions treatment, refer to API Publication 421, Design andOperation of Oil-Water Separators.

f) Current process operating practices should beinvestigated to determine if good housekeeping practices areemployed and if changes can be made to reduce waste materials oruse of excess water. In many cases, proper attention to controlof operations can greatly reduce the amount of soluble oilrequiring treatment. Minimizing leaks and contamination,avoiding spills, and discarding oil only when it is no longerserviceable should be a part of any oil disposal program.

g) Know the location of all separators and the pointof discharge (such as to storm sewers, sanitary sewers, septictanks, or discharge to surface waters).

h) Understand where the monitoring points are andwhat the discharge limits are for separators.

i)Assist in eliminating unpermitted pollutants. Helpimplement source control plans and identify problem areas whereindustrial discharges that may contain hazardous wastes, heavymetals, or emulsified oils are being discharged to an oil/waterseparator system not designed to treat such wastes.

j) Identify to unit/activity personnel and theenvironmental staff those oil/water separators that containexcessive amounts of soilds. This characteristic may indicatethat exterior vehicle or equipment washing (which is usually notallowed in maintenance areas) is being performed at maintenancefacilities.

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k) Educate installation staff to encourage use of drycleanup procedures. For example, floor drains from maintenanceareas to oil/water separators should be used only for finalrinsing of the floor after any oils or other spill materials arecleaned up with dry materials.

l) Remove and test oil/water separator sludge priorto disposal to ensure compliance with the sludge disposalrequirements. Normally the sludge is tested once, shortly afterthe separator is placed in service, to characterize the settledsludge. If the sludge is hazardous, the source of the hazardouspollutants should be immediately identified and eliminated. Thesludge must be retested each time a significant change occurs inthe influent to the separator. Testing and appropriate sludgedisposal should be coordinated through your environmental office.

5.5 O&M of Oil/Water Separators. The ability of oil/waterseparators to function properly depends on the application ofrequired routine service and maintenance. Mechanical equipmentassociated with separators should be maintained according tomanufacturers’ recommendations.

Personnel using and maintaining the system are expectedto understand the separation process and the components of thespecific oil/water separator. Maintenance personnel are expectedto be familiar with the piping and configuration of eachseparator for which they are responsible. They shouldperiodically inspect all parts of the separator and its drainingsystem to prevent failures caused by operations, breaks, andmechanical settings. Items suggested for inspection and arecommended frequency for inspection are listed in Table 3.System users must also be familiar with the capacity of theseparator and holding tanks, uses of the system, and itspotential misuses to be able to determine requirements forperiodic draining and cleaning.

Separator performance can be an important indicator ofthe mechanical condition of the device. Performance can betracked by regular influent and effluent sampling and analysis.

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Table 3Recommended Inspection Points for Oil/Water Separators

Item Suggested FrequencyConventional Gravity Separator

Flight mechanism: flights, chains, sprockets, rails, drive

Visual weekly; detailedannually

Sludge hopper valves: open/close freely, close tight

Weekly

Oil skimmer mechanism: moves freely, level, not plugged

Weekly

Skimmings pump(s) WeeklySludge pump(s) Weekly

CPI SeparatorParallel plates: fouling WeeklySkimmer weir: level AnnuallySkimmings pump(s) WeeklySludge pump(s) Weekly

FlotationSurface skimmer mechanism: ddrive, flight, roller, beach

Visual weekly; detailedannually

Bottom rake: flight AnnuallyPressurization pump and tank WeeklyBack pressure valve: holds recommended back pressure

Weekly

Sludge valve: operates freely, closes tightly

Weekly

Skimmings/bottoms pump(s) Weekly

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Parameters of concern are those that would be expected to beremoved or reduced across the separator: oil, grease, and totalsuspended solids. Data obtained from the analyses should beplotted in a trend plot showing both influent and effluentconcentrations. Effluent concentrations should be compared withinfluent concentrations to detect performance deterioration andwith discharge permit limits obtained from the installation’senvironmental office to assess permit compliance. Frequency ofseparator effluent sampling should be as required by thedischarge permit. Influent sample frequency should be the sameas effluent sampling frequency. At a minimum, twice monthly isrecommended.

5.6 Guidance Documents. The following documents provideadditional guidance in operating and maintaining oil/waterseparators.

a) HQ AFCEE Video, Proper Operation and Maintenanceof Oil/Water Separator. Brooks AFB, DSN:240-4214 (Web address:http://www/afcee.brooks.af.mil/pro_act). This video providesinstruction for installation personnel from Logistics,Maintenance, and CE functions on the operation, effects of abuse,and maintenance of oil/water separators.

b) API Publication 421, Design and Operation ofOil/Water Separators, American Petroleum Institute, February1990. 1220 L Street, Northwest, Washington, D. C. 22005.

c) HQ USAF/CE Memorandum, Oil/Water Separator:Operations, Maintenance and Construction, October 21, 1994. Thismemo includes the Environmental Compliance Policy for Oil/WaterSeparator Operations, Maintenance, and Construction.

d) Thomas D. Aldridge, Jr. “What Is an Oil/WaterSeparator, and Why Do I Need One”? Pollution Equipment News,December 1996.

e) HQ AFCEE ProAct Fact Sheet: Oil/WaterSeparators. (Web address:http:/www.afces.brooks.af.mil/pro_act/main//proact4.htm).December 1996. A Base-level Prevention Resource.

f) ETL 1110-3-466, Selection and Design of Oil andWater Separators. Department of Army, U.S. Army Corps ofEngineers, Washington, D.C. 20314. August 24, 1994.

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Section 6: SEPTAGE MANAGEMENT

6.1 Septage Management Alternatives. This section providesinformation on the characteristics of septage, the monitoring andmanagement of septage collected from various locations anddelivered to the site, and various methods typically used totreat septage.

Approval must be obtained from your environmentaloffice before a treatment system receives septage because thetreatment system is likely to be disrupted from the high strengthof septage and because there is a potential for toxic components.

6.2 Septage Characterization. Septage is generally definedas the liquid and solid material pumped from septic tanks, greasetraps, pit privies, vault toilets, recreational vehicle disposalstations, cesspools, and similar holding tank locations whilethey are being cleaned. Septage is not industrial waste. Themajority of the wastewater that is discharged to a septic tank isabsorbed into the surrounding drain field. The materialremaining in the tank is characterized by a high content oforganics, grease and other floatables, and grit. The quantityand constituents of septage vary significantly depending on thesource and seasonal effects such as groundwater levels.

The quality of septage can also be negatively affectedby industrial contributions if significant concentrations ofindustrial process wastewater or by-products have been mixed witha load of septage. Therefore, to minimize the potential for atreatment plant upset or for discharge of toxic materials to theenvironment, septage entering a treatment facility should bemonitored in accordance with par. 6.3.

6.2.1 Septage Quantity. The most accurate method forestimating future septage quantities is to review historical datafrom local haulers. They should have records of the quantity ofseptage pumped over specific periods. Septage quantities canalso be estimated by multiplying the number of residential septictanks in a service area by the average pumpout volume per unit,as follows:

No. of Septic Tanks x Typical Volume of Septic TankPumpout Interval

An average volume of a septic tank is approximately750 gallons (2.8 cubic meters). A typical pumpout interval for a

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residential home is 3 to 5 years. Any known, significantindustrial, institutional, or commercial contributions would needto be added to this estimated volume.

The pumping of septic tanks is typically seasonal,depending on the geographic location. Most of the pumping occursduring periods of high groundwater or significant rainfall orsnowmelt. During the winter months in cold climates, lessseptage is pumped because of the problems associated withlocating and uncovering septic tanks under snow or in frozenground.

6.2.2 Characteristics of Septage. Septage can be generallydescribed as having large quantities of grease, oil, suspendedsolids, organic matter and grit; foaming upon agitation; beinganaerobic and odorous; being difficult to dewater; and havingpoor settleability. Septage has a high waste strength because ofthe accumulation of scum and sludge in the tank.

The specific constituents of septage vary significantlydepending on the source. Table 4 summarizes septageconstituents, the range of concentrations of these constituents,and typical design values used for septage treatment facilities(EPA Septage Treatment and Disposal Handbook, October 1984).

6.2.3 Comparison of Septage and Domestic WastewaterCharacteristics. Many of the constituents of septage are similarto those of domestic wastewater. Table 5 compares septage anddomestic wastewater characteristics (EPA Septage Treatment andDisposal Handbook, October 1984). The primary difference is thatthe constituents in septage are more concentrated, includinggreater amounts of organics, plastics, hair, and grit.Therefore, depending on the volume of septage discharged, septagecould impart a significant demand on the wastewater treatmentprocesses and increase the maintenance of pipes and equipment.The organic loading from the daily discharge of septage from one1,000-gallon (4 cubic meters) tank truck is equivalent to adomestic wastewater flow of about 30,000 gallons (120 cubicmeters) per day.

6.3 Monitoring the Quantity and Quality of IncomingSeptage. Because of the variability of the constituents andstrength of septage, monitoring incoming septage is necessary toensure its compatibility with the downstream treatment processesand effluent and biosolids disposal requirements. Comprehensiveand organized procedures for monitoring, sampling, and

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recordkeeping should be established and customized for eachseptage receiving and treatment facility.

Table 4Physical and Chemical Characteristics of Septage(1),(2)

Parameter Average Range

SuggestedDesignValue(2)

TSS 12,862 310 - 93,378 15,000VSS 9,027 95 - 51,500 10,000BOD5 6,480 440 - 78,600 7,000COD 31,900 1,500 - 703,000 15,000TKN 588 66 - 1,060 700NH3-N 97 3 - 116 100Total P 210 20 - 760 250Alkalinity 970 522 - 4,190 1,000Grease 5,600 208 - 23,368 8,000pH -- 1.5 - 12.6 6.0

Source: EPA Septage Treatment and Disposal Handbook,October 1984

(1) Values expressed as mg/L, except for pH.(2) The data presented in this table were compiled from many

sources. The inconsistency of individual data sets results in some skewing of the data and discrepancies when individual parameters are compared. This is taken into account in offering suggested design values.

BOD5 = 5-day Biochemicaloxygen demandCOD = Chemical oxygendemandNH3-N = Ammonia-nitrogenP = Phosphorus

TKN = TotalKjeldahl nitrogenTSS = Totalsuspended solidsVSS = Volatilesuspended solids

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Table 5Comparison of Septage and Domestic Wastewater(1)

Parameter Septage(2)DomesticWastewater

Ratio of Septageto Wastewater

TSS 15,000 220 68:1VSS 10,000 165 61:1BOD5 7,000 220 32:1COD 15,000 500 30:1TKN 700 40 17:1NH3-N 100 25 4:1Total P 250 8 31:1Alkalinity 1,000 100 10:1Grease 8,000 100 80:1pH 6.0 -- --

Source: EPA Septage Treatment and Disposal Handbook,October 1984

(1) Values expressed as mg/L, except for pH.(2) Based on suggested design values in Table 4.

BOD5 = 5-day Biochemicaloxygen demandCOD = Chemical oxygendemandNH3-N = Ammonia-nitrogenP = Phosphorus

TKN = TotalKjeldahl nitrogenTSS = Totalsuspended solidsVSS = Volatilesuspended solids

6.3.1 Monitoring Procedures. Procedures should beestablished to monitor the volume and characteristics of incomingseptage flows. These procedures should generally include thefollowing:

a) Record the name of the hauler, the origin of theseptage, and the time of arrival.

b) Record the septage volume discharged to the plant.These records are important for reviewing historical septageflows projecting future flows and for estimating the dischargefee to the hauler.

c) Take a grab sample of each truck load and analyzeit, or refrigerate the sample for possible future analyses.

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d) Supervise the hauler’s activities during thedischarge to the receiving facilities.

6.3.2 Sampling. A sample should be taken from each load ofseptage discharged to the plant. The purpose for the sampling isto allow for immediate analysis of the septage if the waste issuspect; to discourage the discharge of unacceptable waste byopenly displaying to the hauler that the septage is monitored;and to establish a trend analysis of septage characteristics byperiodically analyzing samples.

In most cases, the sample would not need to be analyzedimmediately. It can be refrigerated for a period equal to thedetention time through the treatment plant. In some cases,however, especially where effluent discharge limits are verystringent, a pH test, toxicity screen, and microscopicexamination to confirm the presence of biological activity shouldbe performed on each load.

6.3.3 Recordkeeping. At a minimum, the following recordsrelated to the discharge and treatment of septage should be kept:

a) The origin of the septage, including the name,address, and contact for the owner of the septic tank that waspumped

b) The volume of each load

c) The results of any analyses performed on theseptage and a summary of any unusual septage characteristicsobserved, and

d) The name of the hauling company and driver, permitnumber (if applicable), and time of arrival.

6.4 Modes of Septage Treatment. Because of thesimilarities in the characteristics of septage and domesticwastewater, the same treatment processes can be used to treatboth wastes. The septage can be added to the liquid stream,sludge stream, or both streams of a treatment facility. Theselected mode of septage addition will depend on the capacity andtype of processes at the facility. The ability of a treatmentfacility to treat septage is typically limited by the availableaeration and solids handling facility. Before the septage entersthe treatment facility, it should be pretreated, including, at a

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minimum, screening, equalization, and adequate blending with theraw sewage.

Septage can also be chemically stabilized by using lime(CaOH2) in a batch operation and by then applying the septage to apermitted land application site. Lime can effectively destroymost pathogenic and odor-producing microorganisms and has beenshown to improve dewaterability. The Code of Federal Regulations(Part 503) requires that, to land-apply the septage, it must bemixed with the lime to raise the pH to 12 or higher for a minimumof 30 minutes. Special sludge spreading equipment is necessaryto ensure an even application of the septage on the land.Because this treatment method would typically be independent ofthe domestic wastewater treatment processes, it will not bediscussed further in this section.

6.4.1 Estimating Treatment Capacity. The available treatmentcapacity of a system for receiving and treating septage can beestimated by calculating the difference between the designcapacity of the system and the current loading to the system.This information should be available in your environmentaloffice. Given the estimated available capacity, the volume ofseptage that can be discharged to the treatment system can beestimated by using the suggested organic and nutrientconcentrations presented in Table 4.

For example, assume that the available treatmentcapacity of the treatment system was calculated to be 500 pounds(227 kilograms) per day of BOD. The volume of septage that canbe discharged to the system can be estimated by dividing the500 pounds (227 kilograms) by the estimated BOD concentration inseptage of 6,500 mg/L (Table 4). This equates to an allowableseptage volume of approximately 9,000 gallons (36 cubic meters)per day [500 pounds per day x 1,000,000/(8.34 x 6,500 mg/L)].

6.4.2 Co-Treatment of Septage in Liquid Stream. Septageaddition in the liquid stream is the most common method ofseptage treatment at a WWTP. The screened and degritted septagecan be added upstream of the primary or the secondary treatmentunits. Adding septage upstream of the primary treatment unitswill decrease the organic and solids loadings to the secondarytreatment units (e.g. activated sludge system) and will reducethe potential for scum accumulation in the downstream processes.Other general considerations when adding septage to the liquidstream include the following:

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a) Slug loads versus continuous discharge of septage.The allowable loadings should be reduced by nearly one-half forslug loadings. Estimating allowable loadings is discussed inpar. 6.4.1. Because of shock organic loadings and otherundesirable process impacts, slug loads are not recommended.

b) Timing of discharge. If the available primarytreatment and secondary treatment capacities are limited, theseptage could be metered into the plant during off-peak demands.

c) Ultimate disposal from the treatment facility. Thepermit limitations or other requirements for disposing of thetreatment plant effluent and biosolids need to be considered whenaccepting septage. The organic and inorganic constituents of theseptage may affect the effluent and biosolids quality, includingconcentrations of BOD, TSS, nitrogen, phosphorus, and heavymetals.

d) Scum accumulation in the clarifiers. The scumhandling equipment for the primary and secondary clarifiersshould have the capacity to handle the increased loadings of oil,grease, and floatables.

e) Increased sludge volumes. The volume of primaryand waste activated sludges will increase. Therefore, theprocesses and equipment used for handling the sludge should havethe capacity to accommodate the increased sludge quantities.

f) Location of septage addition to a trickling filterplant. Septage should be discharged upstream of primaryclarifiers if trickling filters are used for secondary treatment.This will minimize the potential for filter media fouling.

6.4.3 Co-Treatment of Septage in Solids Stream. The screenedand degritted septage can be mixed and treated with primary andsecondary treatment plant sludges. Adding septage to the solidsstream nearly eliminates any adverse effects on the liquidtreatment processes and equipment. The undesirable constituentsof septage are kept out of the major flowstreams of the plant,thereby requiring less operation and maintenance.

Depending on the ultimate disposal method,stabilization is normally required prior to disposal. Theseptage can be treated using either aerobic or anaerobicdigestion, the most common methods of sludge stabilization. The

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following should be considered when adding septage to the solidsstream:

a) Increased sludge volumes. The volume of sludgeswill increase; therefore, the processes and equipment used forhandling the sludge should have the capacity to accommodate theincreased sludge quantities.

b) Foaming and odor problems. Foaming and odors arecommon with aerobic digestion. The extent of foaming depends onthe amount of detergents present in the septage.

6.5 Receiving Station. In addition to the high organiccontent, septage typically contains hair and other stringymaterial, grit, and plastics. Also, the volume of septage loadsdisposed of at treatment plants is highly variable. Therefore, aseptage receiving station with preliminary treatment and storageand equalization capacity is highly recommended.

6.5.1 Receiving Station Description. The extent offacilities necessary at a receiving station depends on thequantity of septage received, the flows to the WWTP, thepreliminary treatment available at the plant, the type of septagetreatment used, and the WWTP processes. However, the primarycomponents in most receiving stations should include thefollowing:

a) Dumping station

b) Screening facility

c) Grit removal system

d) Grinder pump (if screening and grit removal is notpresent)

e) Storage and equalization capability

f) Lift station

g) Odor control capability

6.5.2 Dumping Station. The purpose of the dumping station isto provide for the unloading of incoming septage that has beentransported to the plant via tank trucks. The dumping stationshould consist of a truck unloading pad(s), an inlet hose or a

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grate, and washdown hoses. In most cases, the hauler will notifythe operator upon arrival and provide pertinent information suchas name of hauler, origin of septage, and certification, ifapplicable. The monitoring of septage quantity and quality, asdescribed in par 6.3, should take place at the dumping station.

6.5.3 Screening Facility. The septage typically flows bygravity from the dumping station to the screening facility. Thepurpose of the screening facility is to remove the large solidsto protect the downstream treatment processes and associatedequipment. The screens, or “bar racks,” can be manually ormechanically cleaned. Provisions should be available toefficiently dewater and dispose of the screened materials. Thiswill minimize the potential for odors.

6.5.4 Grit Removal System. The screened septage will flow bygravity to the grit removal system. The purpose of the gritremoval facility is to separate the sand, gravel, cinders, foodparticles, etc., from the septage while maintaining the organicmaterial in the main flow for downstream treatment. Effectivegrit removal systems include aerated grit chambers and vortex-type chambers. A grit removal facility may not be necessary ifsufficient grit removal is provided as part of the liquid orsolids process treatment units.

6.5.5 Grinder Pump Stations. Grinder pumps and other typesof wastewater grinders are sometimes used for primary treatmentin lieu of screening. Grinders screen and shred material intosmaller sizes without removing the particles from the flow.Grinders reduce odors, flies, and unsightliness often associatedwith screening and essentially eliminate the steps of screeningremoval and handling, which may not be practical for smallertreatment systems.

Unfortunately, solids from grinders cause problemsdownstream, including deposits of plastics in sludge handlingfacilities. Pulverized synthetic materials will not decompose inthe sludge digestion process and therefore may affect some sludgedisposal methods, especially land application. Using grinderscan also result in “ropes” or “balls” of material (particularlyrags) that can clog downstream equipment such as pipes,diffusers, pumps, and aerators.

6.5.6 Storage and Equalization. The purpose of septageholding basins is to provide storage, equalization, and mixingprior to further treatment. Storing the septage will help reduce

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the peak loadings to the downstream processes and help maintainthe appropriate blending of septage with the raw sewage. Thestorage tanks also provide flexibility to store the septage loadwhile analyses are being performed. Provisions should be madefor mixing the contents of the storage tank. The storage can beprovided either upstream or downstream of the screening and gritremoval facilities.

6.5.7 Lift Station. A lift station is typically required topump the septage from the receiving station to the downstreamseptage treatment processes.

6.5.8 Odor Control Capability. The extent of the odorcontrol that is required depends on the location of the facilityrelative to the surrounding area and the land use of that area.Many of the odors can be minimized by following good housekeepingpractices. The dumping area should be hosed down after eachdelivery (preferably by the hauler), the bar screens should bekept clean, and the waste solids removed during pretreatmentshould be dewatered and disposed of as soon as practicable.

If the odors are excessive and must be eliminated, thespecific sources of the odor should be identified and contained,and the odorous air should be vented to a treatment unit.Several treatment technologies are available, including liquidchemical scrubbers, activated carbon filters, biofilters, and theaddition of gases to a biological treatment process.

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Section 7: EXTREME CLIMATE OPERATION

7.1 Effects of Extreme Cold Climates. Cold weather canhave significant and often severe adverse effects on themaintenance, operations, and performance of WWTPs. Temperature-dependent effects include physical, chemical, and biologicalresponses. Often performance efficiency will be affected byextreme cold weather, which can cause treatment processes tosuffer. The structures and buildings will also be affected byexcessive snow loads, snow drifting, ice formation, and relatedfreezing of system components. These factors will affect the O&Mof the facility. Major cold weather operational problems can bedivided into four specific categories:

a) Changes in the viscosity of the wastewater andequipment lubricants

b) Reaction rate changes in physical, chemical andbiological processes

c) Ice formation and freezing in process components

d) Snow and ice accumulation on structures, controlequipment, roads and walkways, and walls and berms

The potential for winter and cold weather problems isnot limited to a particular type of treatment process nor to anyparticular size of treatment plant. Table 6 lists areas within aplant where cold weather may affect plant performance,operations, or maintenance.

Additional information about cold weather problems canbe found in U.S. Army Cold Regions Research and EngineeringLaboratory (CRREL) Special Report 85-11, Prevention of Freezingand Other Cold Weather Problems at Wastewater TreatmentFacilities.

7.2 Preliminary Treatment Processes. As wastewater entersthe treatment plant, the preliminary processes will be affectedby the cold water and freezing weather. These processes areintended to remove large solids and abrasive material. Thefailure of any of these units will affect downstream processes.Therefore, it is important to keep these units working aseffectively as possible. This discussion is also applicable tocollection system pumping stations that may be equipped with

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similar equipment. Table 7 suggests solutions to these coldweather problems.

Table 6Treatment Process Components Subject to Freezing Problems

PreliminaryTreatment Clarifiers

BiologicalReactors

SolidsManagement Disinfection

Pumping Primary Activatedsludge

Digestion Chlorination

Screens Secondary Extendedaeration

Dewatering

Grinders Polishingponds

Oxidationditches

Disposal

Grit chamber Airflotation

Tricklingfilters

Flowmeasurement

Thickeners Rotarybiologicalcontactors

Flowequalization

AeratedlagoonsFacultativelagoons

Source: U.S. Army CRREL Special Report 85-11

Table 7Winter Problems with Preliminary Treatment

Problem SolutionIce buildup in headworks area Keep building heated above 50°F

(10°C).Icing of bar racks Cover inlet channel.

Flush with warm water.Weatherstrip channels to reducecold air entry into building.Clean by hand frequently.

Septage pumping lines freeze Use heat tape on lines andvalves.Use proper flushing afterpumping truck.Use manhole to directly dumpinto plant.Do not handle septage inwinter.Drain all lines.

Septage freezing in truck Pass engine exhaust throughtruck tank to prevent freezing.

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Table 7 (Continued)Winter Problems with Preliminary Treatment

Problem SolutionDrain truck tank pipings andvalves.

Collected grit freezes Store dumpsters in heated buildingbefore emptying.Store truck inside.Remove no grit in winter.

Icing of grit dewateringequipment

Duct kerosene heater into area.

Grit machine freezes Enclose unit.Screened rags freeze Remove regularly by hand.Spiral lift pumps freeze Run water on ice to reduce

buildup.Screw pumps freeze Install timer to “bump” screw once

per hour.Valves and hoses freeze Drain lines.

Keep hoses on.Automatic sampler freezes Place sampler inside building

Do not use in severe cold.Build insulated structure heatedwith light bulb. Insulate suctionlines. Purge lines after sampletaken.Move sampler location to decreaseexposure. Install suction lines togive a straight fall.

Flow measurement device freezes Use heat tape and glass fiberinsulation on flow transmitter.Insulate chamber and heat with onelight bulb.Put heat tape on Parshall flumelinkage.

Float for flow measurementfreezes

Heat with light bulb and insulate.

Add antifreeze to float box.Grit removal bypass channelfreezes

Temporarily switch flow to by-passchannel, 30 min/day or more oftenif needed.

Water freezing at comminutor Build plexiglass structure to keepinfluent warm.

Doors frozen shut onscreening enclosure becauseof condensation

Put heat tape around doorenclosure.

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Table 7 (Continued)Winter Problems with Preliminary Treatment

Problem SolutionStairs above screw pumpsare slippery from icingcondensation

Plant policy requires alloperators to keep one hand freeat all times to use rails.

Source: Taken in part from U.S. Army CRREL Special Report 85-11.

7.2.1 Screens and Grinders. Screens should be cleaned morefrequently during cold weather, either automatically on timers ormanually, since the screenings will freeze to the metal bars.Once this occurs, removing screenings from the bars is verydifficult. Mechanical mechanisms may also become jammed andinoperable. Weatherproofing or enclosing the area and providingheat may be desirable.

Caution: Be aware of the potential for combustiblematerials entering with the wastewater. Provide properventilation and equipment to prevent explosive conditions.

Screenings may freeze to the sides and bottom ofcontainers; prevent this from happening if at all possible.Grinders may bind because of ice if they are not run oftenenough. Consider operating the grinders continually or oftenenough to prevent ice buildup. Covering channels with rigidinsulating materials may contain enough heat from the wastewaterwithin the channel to prevent ice buildup on the grinder. Gearoil viscosity will be affected by freezing weather. Follow themanufacturer’s recommendations for cold weather maintenance.Condensation will also occur in the gear boxes of this equipment,adversely affecting the gear oil. Check the oil routinely (twicemonthly) in the winter.

7.2.2 Grit Removal Processes. Operation of grit-handlingfacilities may be very difficult during extremely cold weather.The grit that is collected and transported will freeze easily inthe equipment used to clean and move it to the holding container.Temporary enclosures may assist in keeping the process warm. Ifthis process is to be enclosed, choose the materials carefully toprevent dangerous or explosive conditions. Heat-tracing themetal equipment may help prevent ice buildup. Heat-tracinginvolves wrapping an electrified wire loop around the equipment.

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Running warm water across cleaning areas may also preventfreezing, depending upon local conditions.

7.2.3 Flow Measurement. Freezing weather conditions maycause the stilling well of flow measurement devices to freeze.A solution of mineral oil, or a small amount of antifreeze or asalt solution, will keep this stilling well liquid. Under low-flow conditions, some of this antifreeze will drain out and mayneed to be replenished periodically. Other remedies are toenclose the area with rigid insulating board or plywood and touse a light bulb for heat. Enclosing float wires will preventthem from freezing.

A layer of frost may coat ultrasonic sensors inside thecone on the sensor head. Use a thin layer of petroleum jelly onthe face of the detector to prevent this problem. Note that thesensor should be recalibrated after the jelly is applied.In systems that have an air bubbler system to measure the levelof water, condensate may become trapped within the air line andit may freeze. Heat-tracing the air line will prevent freezingand condensate problems. Dry air will also help preventcondensate freezing in the lines. Using a desiccant on the airsupply is recommended.

7.2.4 Other Preliminary Treatment Processes. Sometimesseptage trucks discharge material to the headworks of the plant.To ensure that the discharge hoses do not freeze, drain themcompletely and hang them up so that water does not collectinside. On fixed lines, heat tracing will prevent the liquidfrom freezing. However, fixed lines should be installed with aslope to drain. Septic trucks should be kept in heated garagesbecause they have many parts in which water may freeze, includingthe pumps, valves, piping, and tank. Tankers should becompletely empty if they are left out in the freezing weather.

Automatic samplers should be housed in a heated andinsulated compartment. Sampler suction lines should be heattraced or enclosed in a heated space. A light bulb in thesampler “shed” can supply enough heat to prevent the sampler fromfreezing. A small shelter the size of a doghouse may be suitablefor this purpose, if it is insulated. Operate screw pumpsroutinely to prevent the shaft from freezing to the walls of thechute. Rotate the screw pumps a few turns every half hour toensure that they do not freeze. The rotation can be performedwith a simple timer.

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7.3 Clarifiers. Clarifiers are affected in several ways bythe decrease in seasonal temperatures. The density of waterchanges with temperature, and this change affects the settlingcharacteristics of the solids. Materials at the surface of thesequiescent basins will tend to freeze. Weirs and launders mayalso freeze, depending upon the ambient and wastewatertemperature. Table 8 summarizes some potential problems andsolutions associated with clarifier freezing.

7.3.1 Surface Freezing Conditions. The most serious problemassociated with clarifiers is freezing on the surface, surfacescum, and ice buildup on the scum beach plate. These problemsdamage skimming mechanisms and may even cause the clarifier rakemechanism to fail. Check torque limits on the rake mechanismroutinely and adjust them if necessary to ensure that they willwork if ice affects the collector. Removing the skimming arm inwinter may prevent this problem; however, the problems of scumfreezing and removal remain. Hot water sprays, heat tape, andenclosed lamps may be valuable in addressing these problems.Many times, ice must be carefully chopped off the surface of thetanks and removed to the launders.

Table 8Winter Problems with Clarifiers

Problem SolutionScum line freezes Flush out with hot water. Use

sewer bag to free blockages.Install automatic flushingmechanism.

Scum trough freezes Cover exterior trough.Break ice into pieces and removeby hand.Install automatic flushingmechanism.

Scum freezes on beaching plate Flush off with hot water.Discontinue scum removal inwinter.Shovel and hose down by hand.If adjustable, decrease exposedplate area.

Ice on beaching plate hangs upcollector arm and damagesmechanism

Remove skimmer during winter.Remove ice by hand.

Scum freezes on outside ring ofperipheral feed clarifier

Cover clarifier.

Scum solidifies, won’t flow Use warm water to flush.

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Table 8 (Continued)Winter Problems with Clarifiers

Problem SolutionScum freezes at center feed Install a warm water sprayer

to keep scum moving towardskimmer.

Surface icing Remove secondary arms toprevent damage.Keep clarifiers on 24hours/day.Remove thick ice with long-armed backhoe.Shorten detention times.

Icing in idle units Pump units dry routinely.Icing in gear units Install heat tapes on drain

line.Drain water in bullgear afterrain and when temperaturerises.

Hoses and hydrants freeze Leave lines on.Drain lines after use.

Traveling bridge controlsice-up

Build enclosure over controls.

Icing of bus bar for bridges Install heat guns or warm airblower.

Switches on monorakes freeze Shut off units in snow and iceto prevent freezing.

Accumulation of snow onmonorake rails stops wheels

Shut down rake duringsnowstorms and remove snow.

Automatic sampler freezes Build insulated boxes heatedwith a 100-watt light bulb.

Waste activated sludge linesfreeze

Locate lines deeper.Install proper drainage.

Source: Taken in part from U.S. Army CRREL Special Report 85-11.

Caution: Take care during this operation sinceslippery footing, loss of equipment (attach lines and floats),and damage may result during ice removal.

Covering clarifiers will eliminate many of thesepotential problems. When designing covers, consider snow loads,

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weatherproofing of electrical controls, and the possibility ofhumidity within the covers.

7.3.2 Mechanical and Electrical Equipment Protection. Theviscosity of lubricating oils will change as a result of freezingtemperatures. The operator can either change the oil to suit theexpected temperature range or use heat tape or immersion-typeheaters to maintain higher oil temperatures. Sometimes multi-viscosity year-round synthetic oils may be appropriate. Gearboxes tend to collect moisture and condensate, which may eitherdegrade lubrication oil or cause corrosion. This conditionshould be monitored. Frost may arc across some electricalcircuits; a small warm-air fan at the motor control center ventwill keep these components warm and dry if this is a local issue.

7.3.3 Process Concerns. Settling characteristics change whentemperatures lower; solids settle at a slower rate in colder(near freezing) waters. Stoke’s Law governs the physics ofsettling in primary clarifiers, and it is affected bytemperature. For example, when the temperature drops from 68°F(20°C) to 38°F (3°C), the settling time for a particle increases 64percent. Under these conditions, additional clarifiers mayfacilitate the process. However, proceed with caution becausethe increased detention time caused by additional clarifiers willresult in lower water temperatures and a higher risk of freezing.If the solids loading is very high (above 2,000 milligrams perliter [mg/L]), Stoke’s Law does not apply.

7.4 Biological Systems. Biological reaction rates dependupon temperature. A drop in temperature of 10°C (18°F) decreasesthe reaction rates by one-half. Mechanical equipment providingaeration is affected by freezing temperatures, and ice may affectthe components. Table 9 suggests some solutions to freezingproblems in biological systems.

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Table 9Winter Problems with Biological Systems

Problem SolutionIce buildup on surface aerator Remove by hand.

Run on high speed for15 minutes.Turn off for 1/2 hour, allowmixed liquor to warm aerator,and turn on high speed.Steam ice off.Bump aerator on and offcarefully.

Impeller icing causing pondingon fixed shroud

Remove shroud. Ice will stillbuild up, but aerator will notbe damaged.

Ice buildup on supportingcolumns causing rotatingshroud to pond on columns

Shorten detention times; runaerators on timers.

Cooling of mixed liquor Install timers on aerators.Use diffused air instead ofsurface aeration.Remove some aerator blades.

Icing in idle tank damagingstructure

Fill tank 1 foot above baffle.Install small sump pump to keepsurface free of ice.Exercise units regularly duringsunny days. Care must be takennot to damage units.Use inner tubes to absorb iceexpansion.Bubble air to prevent freezing.

Ice buildup on splash guard,electrical conduit, andwalkways

Use good snow and ice removalprocedures, salt.

Plant policy requires operatorsto keep one hand free to holdrailing.

Decreased removal efficiencies Increase MCRT, decrease F/M.Source: Taken in part from U.S. Army CRREL Special Report 85-11.

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7.4.1 Activated Sludge Systems. Cold weather does not affectconventional activated sludge systems with a detention time of4 to 6 hours as significantly as systems with longer detentiontimes. Extended aeration systems having detention times of 10 to24 hours will experience a temperature decrease that will affectthe biological process. Systems that use diffused air for oxygentransfer will actually be adding heat to the system in the airflow; conversely, mechanical mixing systems will have significanttemperature decreases across the aeration basin as cold air ismixed into the activated sludge. Take these temperature changesinto consideration when selecting or changing aeration methods ina cold climate. Avoid ice buildup across the surface of thebasins. This buildup will limit the oxygen transfer and mayinterfere with mixing equipment. Removing floating scum beforewinter will help prevent this extra material from freezing in theaeration basin.

In cases where the temperature is affecting theprocess, changes to the process control are required. Processadjustments would include increases to the mean cell residencetime (MCRT) or a decrease in the food-to-microorganism ratio(F/M) to maintain the same process performance and loading rates.

Ice buildup around mechanical aeration equipment willalso affect safety and may overload equipment if it attaches toequipment surfaces. Continuous operation of mechanical mixers atlow speed or intermittent operation will reduce the oxygentransfer and reduce ice buildup. Monitor oxygen concentrationclosely if this method is attempted. Heat tracing the componentsmay also be helpful.

7.4.2 Fixed Film Treatment Systems. In trickling filterplants, the potential for icing is very high. In winter, turnoff the draft in forced-draft systems unless a source of warm airis available.

Note: The forced draft systems are used primarily whenthe outside air is less than 5°F (3°C) above or below the processliquid temperature. If ice forms within the unit, flood it tomelt the ice. Take care when flooding the media, and be cautiousof structural loading as well as leaking and overloaded pumpingsystems, gates, and valves. Ice can form on the top of themedia, which may affect the distributor arm. Covers are advisedin extremely cold areas to prevent this situation.

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Rotating biological contactors (RBCs) are usuallycovered to control odors, but keep the covers in good conditionto keep the heat within the wastewater. If the RBCs do notalready have covers, install them to keep the media from freezingand affecting the shaft with additional loading and potentialfailure.

7.4.3 Lagoon Systems. Aerated lagoons will typically freezeduring the winter. Remove mechanical mixers to prevent them frombecoming covered with ice and turning over or sinking. Removeany baffles as well, or be prepared to repair them in the spring.Because the ice will affect the depth of the lagoon, winteroperations should be run at the highest liquid levels possible toincrease lagoon volume. Because of the ice coverage, little tono algae activity will occur under the ice and snow. Adding thelower water temperature to the situation, lagoon performance inthe winter may be marginal. With the rise in springtemperatures, the lagoons will have a liquid turnover, with apossible washout of solids.

7.5 Disinfection. Chlorine gas cylinders need to be in aheated environment because evaporation chills the contents whenthe gas vaporizes in the tank. The EPA recommends keeping thetemperature of the chlorine room no lower than 50°F (10°C).External heat sources should not be too high (cylinders shouldnot be higher than 158°F [70°C]), but heat should be considered ifit will solve the vaporization problem. Hypochlorite tabletswill dissolve more slowly in cold water. Additional tablets maybe necessary to achieve the proper levels of disinfection. Alllines carrying disinfection chemicals and solutions should beheat-traced where they are exposed to freezing conditions.Table 10 lists disinfection freezing problems and remedies.

Table 10Winter Disinfection Problems

Problem SolutionFeed lines freeze Enclose all storage and

pumping facilities in aheated building.

Hypochlorite solutioncrystallizes in pumps and pipes

Keep in heated room above65°F (18°C).

Surface contact chamber freezes Cover and insulate tanks.Source: Taken in part from U.S. Army CRREL Special Report 85-11.

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7.6 Solids Management. Solids digestion is a biologicalprocess that slows down as a result of decreasing processtemperatures. Solids processing equipment exposed to theelements will be adversely affected by freezing weather.Table 11 summarizes problems associated with solids management inwinter and offers possible solutions.

Table 11Winter Problems with Solids Management

Problem SolutionUnable to use solids dryingbeds in winter; beds freeze

Cover beds.

Not able to apply solids toland in winter

Stockpile solids in wintermonths.

Aerobic digester freezes ifblower is shut off to allowthickening by decanting

Cover tank.Decant smaller amounts moreoften.

Solids mixture freezes in tank Run mechanical agitatorovernight.

Ice forms on digesters Insulate better.Icing in gravity thickener Run final effluent to keep

hydraulic loading higher.Solids holding tank freezes Take offline during winter.Solids freeze on truck Use truck body heated with

exhaust gases.Solids lines freeze; valvesfreeze

Drain lines correctly.Dismantle and thaw valve.Put heat tape on lines.Increase return rates.

Holding tanks too small tolast winter

Use spare clarifier ofoxidation ditch.

Extensive heat loss fromanaerobic digester

Improve insulation.

Operating temperature couldnot be reached in a newcompost pile

Cover pile and insulate.Mix solids and wood chips withhot compost.Blow hot exhaust from workingpile into new pile.

Source: Taken in part from U.S. Army CRREL Special Report 85-11.

7.6.1 Aerobic Digesters. Aerobic digesters will operate atlower efficiencies. Longer detention times will be required toobtain the needed levels of stabilization. Digester solidsconcentrations should be increased to accommodate these changes.

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Thus, decanting the digesters may take longer as a result ofincreases in viscosity.

7.6.2 Anaerobic Digesters. It will take more energy to keepthe contents up to the processing temperature because of thelower feed temperature. Tank insulation (dome and sides) willneed to be inspected in the fall of each year and repaired asneeded.

7.6.3 Dewatering. Dewatering on drying beds can take longerbecause of freezing beds. Where solids drying is necessary,maximize the dewatering in the warmer and dryer summer months.It is often faster to apply thin layers of solids, allow thesolids to dry, clean the beds, and reapply solids than to applyone thick layer. If adequate capacity exists, keeping the solidson the frozen beds throughout the winter is satisfactory.

7.6.4 Equipment Maintenance. All equipment that containssolids mixtures and can be exposed to freezing temperaturesshould be insulated and heat-taped. If equipment is not requiredduring the winter, drain it completely and store it for theseason. Equipment in which condensate can collect should beemptied often to prevent freezing. For example, enclosedcabinets (switch gears, mechanical enclosures, and pneumaticsystems, etc.) that are exposed to liquid streams in whichcondensation may be generated should be either heat traced,drained, or isolated from the condensation source.

7.6.5 Concrete Repair. Concrete exposed to repeatedfreeze/thaw cycles is subject to cracking and spalling. Inenvironmental type structures, the concrete becomes saturatedwith water. When temperatures drop below freezing, the water inthe concrete pores will freeze. As the water freezes, it expandsand exerts pressure on the concrete. When the pressure exceedsthe tensile strength of the concrete, it cracks. The cracks geta little larger each time the concrete freezes. When the waterthaws out, the water shrinks, leaving void areas in the cracks.Through capillary action the crack fills up with more water.Repeated freezing and thawing makes the cracks get larger untilthe concrete spalls off.

Small spalled areas that do not expose the reinforcingare not significant since their effect is more cosmetic thanstructural. Small spalls should be repaired as part of routinefacility maintenance. Patch the concrete with a polymer-modified, silica fume enhanced mortar such as Sika Mono Top

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(manufactured by Sika Corporation, Lyndhurst, New Jersey), orEmaco (manufactured by Master Builders Inc., Cleveland, Ohio).All loose concrete should be removed and the concrete surfacecleaned and prepared as required by the repair mortarmanufacturer.

If the spalling is extensive, if the concrete iscracked and leaking, or if the reinforcing steel is corroded, aconcrete repair specialist should be consulted. The specialistis needed to evaluate the cause of the problem and to specify theappropriate repair. Patching spalled concrete created bycorrosion in the reinforcing will only lead to the patch failingif the corrosion is not addressed first. Cracks in the concretecan be effectively repaired only when the cause of the crack isdetermined. Otherwise, the crack may just form in anotherlocation next to the repaired crack.

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Section 8: CORROSION CONTROL

8.1 Causes of Corrosion. Most corrosion present around aWWTP is called aqueous corrosion because it occurs in a wet ordamp environment. Other forms of corrosion, such as hightemperature corrosion, are not usually found in a WWTP. Aqueouscorrosion can occur on metal surfaces that are a) submerged inwater, b) buried in the earth, or c) wet from surface moisture,such as rain water, condensation, or high humidity. The rate atwhich the corrosion occurs depends on the amount of moisturepresent and what chemicals or other contaminants are present inthat moisture. Aqueous corrosion is also called electrochemicalcorrosion.

8.1.1 Electrochemical Corrosion. Electrochemical corrosionderives its name from the electrical current ("electro") that isflowing and the chemical reactions that occur at the same time.The flow of current is critical, since the amount of currentflowing in a corrosion cell will affect the amount of metal thatwill be corroded. Corrosion currents are direct currents (DC)controlled by Ohm’s Law. Ohm’s Law states that the voltage(E, volts) is equal to the current (I, amperes) times theresistance (R, ohms). The current flow will be directly affectedby the resistance of the corrosion circuit. Wastewater is moreconductive than distilled water; therefore, a corrosion cell inwastewater will be more active than in distilled water.

For an electrochemical corrosion cell to exist, fourelements must be present:

a) an anode or corroding surface;

b) a cathode or noncorroding surface;

c) a metallic connection between the anode andcathode surfaces; and

d) a common electrolyte, which contains both theanode and cathode surfaces.

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The anode/cathode surfaces can exist on the same pieceof metal and can be very close to each other or at a greatdistance from each other. The connection, in a single piece ofmetal, is the metal itself. The typical electrochemicalcorrosion cell is shown on Figure 7. The electrolyte can be anymedia capable of conducting an electrical current. If the metalis buried, the electrolyte is the soil; if the metal is submergedin wastewater, the wastewater acts as the electrolyte.

If one or more of the four elements is eliminated, thencorrosion cannot occur. As discussed below, this fact plays animportant role in controlling corrosion. For example, if apipeline is buried in the soil, many areas of anodes and cathodeswill be present on the surface of the pipeline. These areas aredeveloped during the process of producing the pipe and cannot beeliminated. The connection between the anodes and cathodescannot be broken, since the pipe wall serves this purpose.However, if the outside of the pipe is coated with a protectivecoating or wrapped with pipeline tape, the pipe surface will beisolated or separated from contact with the soil (electrolyte).Isolating the pipe from the electrolyte eliminates one of theelements necessary for corrosion. Therefore corrosion cannotoccur, even though the anodes, cathodes and connections stillexist on the pipe. Methods of handling coating defects arediscussed below.

Cathode

ELECTROLYTE

m+

Anode

m+

H2

e e

e e

e

e

e

e

Figure 7Electrochemical Corrosion Cell

8.1.2 Eight Forms of Corrosion. It is possible to classifyseveral forms of corrosion, based on the general appearance ofthe corroded metal. In most cases, the forms can be identifiedwith the naked eye, but magnification can help. Not every form

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of corrosion is likely to be seen in a WWTP, but it is helpful toknow each form and be able to recognize it in case it occurs.The eight forms of corrosion are unique but are ofteninterrelated:

a) Uniform corrosion

b) Galvanic corrosion

c) Crevice corrosion

d) Pitting corrosion

e) Intergranular corrosion

f) Selective leaching

g) Erosion corrosion

h) Stress corrosion

8.1.2.1 Uniform Corrosion. Uniform corrosion is one of themost common forms of corrosion and probably accounts for thegreatest corrosion loss in the world. It is generallycharacterized by an electrochemical reaction that proceedsuniformly over all exposed surfaces. Uniform corrosion can bepredicted with simple tests, and accurate estimates of equipmentlife may be made. It is easily controlled by selection of propermaterials and by use of protective coatings, inhibitors, andcathodic protection (discussed in par. 8.2). In a WWTP, examplesof uniform corrosion would include unpainted steel tanks andstructures that are allowed to corrode in the atmosphere,resulting in heavy, flaky rusting of all exposed surfaces.

8.1.2.2 Galvanic Corrosion. Often referred to as two-metalcorrosion, galvanic corrosion involves two or more metals thatare electrically connected together in an electrolyte. Galvaniccorrosion is the second most common form of corrosion. Whenevertwo metals are connected together, one behaves as an anode and isalways corroded, while the other behaves as a cathode and is notcorroded. A typical galvanic corrosion cell is shown inFigure 8. This figure is very similar to Figure 7, except thatthe anodes/cathodes are replaced with specific metals. Whichmetal becomes the anode and which the cathode depends upon theirposition in the galvanic series of metals (see Table 12). Forexample, if a copper valve is installed in a steel pipeline, thesteel will always be the anode, since it is lower in the galvanic

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series than is the copper. Therefore, the steel will corrode inpreference to the copper. If two metals are very close to eachother in the galvanic series, the resultant corrosion willprobably not be too serious. The conductivity of the electrolytewill also affect the corrosion cell; increasing conductivityincreases the corrosion activity. The ratio of the surface areaof the two metals involved will also affect the corrosion rate.Large anode surfaces to small cathode surfaces is preferable tothe opposite ratio.

Galvanic corrosion is commonly found in WWTPs. Controlgalvanic corrosion using the following procedures:

a) Select materials that are close together in thegalvanic series.

b) Electrically isolate the two metals from eachother by installing insulating flanges or unions.

c) Maintain a large surface area of the anodic metalcompared with the surface area of the cathodic metal.

d) Paint the metals to reduce the surface areasexposed. It is preferable to paint the cathode to maintain alarge surface area of the anode metal.

e) Introduce a third metal into the circuit that ismore anodic than either of the original metals (lower in thegalvanic series). This form of cathodic protection is discussedin detail in MIL-HDBK-1004/10, Electrical Engineering CathodicProtection.

Copper

ELECTROLYTE

Fe++

Steel

Fe++

H2

e e

e e

e

e

e

e

Figure 8Galvanic Corrosion Cell

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Table 12Practical Galvanic Series of Metals

Platinum CATHODICGoldGraphiteTitaniumSilverStainless steel (passive)Nickel (passive)Copper and its alloysTinLeadCast ironSteel or ironAluminum alloysZincMagnesium alloys ANODIC

8.1.2.3 Crevice Corrosion. Crevice corrosion is a very intenseform of corrosion that is localized within a small crevice orshielded area. Crevice corrosion typically develops in gasketedsurfaces, within lap joints, under sludge deposits, or under boltheads. The crevice must be wide enough to permit the fluid toenter but small enough to create a stagnant condition.

Metals that rely on oxide films for their corrosionresistance (stainless steels and aluminum) are prone todeveloping crevice corrosion. If chlorides are present in thewastewater (possible in WWTPs near sea-coast installations), theywill tend to accelerate breakdown of the oxide film and lead tocrevice corrosion. The use of Type 316 stainless steel insteadof Type 304 will provide improved resistance to chloride-initiated crevice corrosion.

Prevent or minimize crevice corrosion using thefollowing techniques:

a) Use welded connections instead of boltedconnections.

b) Use continuous welds instead of stitch welds.

c) Do not allow solids to settle out in vessels.

d) Use gaskets that do not wick or absorb fluids.

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e) For buried structures, provide uniform, cleanbackfill material.

8.1.2.4 Pitting Corrosion. This form of corrosion is extremelylocalized and is very destructive because a deceptively smallarea of the metal surface is corroded. However, pittingcorrosion can penetrate the metal wall and lead to leaks.Pitting corrosion is difficult to predict because the conditionsthat initiate pitting may not always be present (they may beintermittent or may suddenly arise). The rate of material lossin the pit generally increases as the pitting continues, causingpit depth to increase rapidly. Pitting corrosion is more easilyinitiated in stagnant or low-flow conditions. Often pitting willdevelop under deposits that settle in the bottoms of pipes andtanks or under material that may be splashed onto a surface.Pitting corrosion will also occur at holidays (holes) inprotective coatings.

Metals that rely on oxide films for their corrosionresistance (stainless steels and aluminum) are prone todeveloping pitting corrosion. In WWTPs, stainless steel oraluminum slide gates, handrails, or other components oftendevelop pits, which initiate under a deposit. If chlorides arepresent in the wastewater (possible in WWTPs near sea-coastinstallations), they will tend to accelerate breakdown of theoxide film and lead to pitting corrosion. The use of Type 316stainless steel instead of Type 304 will provide improvedresistance to chloride-initiated pitting corrosion.

8.1.2.5 Intergranular Corrosion. Intergranular corrosion isnot usually encountered in the environments typically found inWWTPs. Under certain conditions, the corrosion experienced willbe concentrated at the grain boundaries of the metal rather thanuniformly across the surface. Grain boundaries most commonlybecome more sensitive to corrosion because of welding duringfabrication. For this reason, intergranular corrosion may alsobe called weld decay, weld attack, weld corrosion, or corrosionof the heat-affect zone.

Intergranular corrosion often occurs with stainlesssteels, which develop sensitized areas around the welds becauseof depletion of one of the alloying elements in the stainlesssteel. The use of the low-carbon grade of stainless steel(i.e., Type 304L or Type 316L) will usually control this problem.Other methods include heat-treatment after fabrication or withthe use of stabilized stainless steels. Intergranular corrosion

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usually occurs in very aggressive environments that are notcommonly found in WWTPs.

8.1.2.6 Selective Leaching. Selective leaching is the removalof one element from a solid alloy by the corrosion process. Theresults are unusual because the corroded metal may not show anyobvious signs of corrosion. Brass alloys are composed primarilyof zinc and copper. Selective corrosion of the zinc from thealloy (dezincification) will cause areas of the alloy to take ona red, coppery color in contrast to the yellow color of thebrass. The result is a weak, porous, and brittle material.Brasses containing more than 85 percent copper are resistant tothis form of corrosion.

Cast iron and, to a lesser degree, ductile ironsometimes show the effects of selective leaching, calledgraphitization. This is the result of selective leaching of theiron matrix in the cast iron, leaving a weak, brittle, graphitestructure. This type of corrosion is often seen with buried orsubmerged pipelines, sluice gates, and other cast structures in aWWTP. Graphitization can be readily detected by a soft graphitestructure that can be cut with a knife. The use of protectivecoatings and cathodic protection easily controls this form ofcorrosion.

8.1.2.7 Erosion Corrosion. Erosion corrosion is usually theresult of movement between a corrosive media and a metal surface.Most metals are susceptible to erosion corrosion, depending upontheir critical velocity. If particles are entrained in the fluidstream (grit streams or sludge streams), erosion corrosion willbe accelerated. Typical locations for erosion corrosion areareas of higher velocities, such as:

a) Piping systems, especially at elbows and tees

b) Across valves, especially throttling valves

c) Pumps

d) Propellers, mixers, impellers

e) Orifices and nozzles

f) Inlets to heat exchanger tubes

Other forms of erosion corrosion are fretting corrosionand cavitation. Control erosion corrosion by minimizing the

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velocities of fluids, selecting materials that are moreresistant, or providing special coatings (such as hard-facingmetals or ceramics) or rubber linings.

8.1.2.8 Stress Corrosion. This type of corrosion has a numberof different names: stress corrosion cracking (SCC), chloridestress cracking (CSC), caustic embrittlement, and seasoncracking. Stress cracking failures can be very sudden, dramatic,and serious, partly because there are often no outward signs offailure. Stress corrosion occurs under tensile stress in acorrosive environment. The stresses can be applied stresses,residual stresses (from fabrication), thermal stresses, orlocalized stresses from welding operations. With stainlesssteels, chlorides can be an initiator; with carbon steel, sodiumhydroxide can initiate failure (caustic embrittlement).

Prevent stress corrosion by providing stress relief,using more resistant materials, applying cathodic protection, orusing inhibitors. Corrosion fatigue is another form of stresscorrosion that occurs after repeated, cyclic stresses. In WWTPs,stress corrosion can occur in sodium hydroxide facilities or inincinerator units without proper stress relief.

8.2 Control and Minimization of Corrosion. With a basicunderstanding of electrochemical corrosion, it is easier tounderstand how various methods of corrosion control work. One ofthe primary methods to control corrosion is to isolate thestructure from its environment (electrolyte) by applyingprotective coating systems (the terms “coating” and “painting”will be used interchangeably in this document; both refer tohigh-performance products). However, even with a high-qualitycoating system, some deficiencies can exist, requiring theapplication of cathodic protection to certain structures. Thecombination of good protective coatings and adequate cathodicprotection can provide good, long-term performance in theaggressive environment of a WWTP.

8.2.1 Protective Coatings. The most important component of acoating is the vehicle, or organic polymer base. This is thematerial that forms the continuous film over the substrate andprotects against corrosion. Common polymer bases include alkyd,epoxy, polyurethane, acrylic, and silicone. These vehicles maybe modified with other materials to form combinations, such ascoal-tar epoxy. See MIL-HDBK-1110, Paints and ProtectiveCoatings for Facilities, for more information on selection andapplication of protective coatings.

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When dealing with coating systems in an existing WWTP,it is very important to know the generic vehicle type used in thecoating. Compatibility between coatings is critical.Incompatible coatings can lead to failures. Generic coatingscommonly used in WWTP include the following:

a) Coal-tar Epoxy. Used extensively in immersionapplications in wastewater and mild chemical exposures, coal-tarepoxy is generally considered to be a self-priming material,applied in two coats of 8 mils (0.008 inches) each.

b) Polyamide Epoxy. Available as a primer,intermediate, or finish coats, Polyamide epoxy is used in moreaggressive environments. Primers are generally about 2 milsthick; intermediate coats may be 4 to 6 mils thick; finish coats2 to 4 mils thick. Epoxy coatings tend to chalk when exposed tosunlight.

c) Polyurethane. Polyurethane is an excellent, hardcoating that has very good color and gloss retention. It is usedextensively over epoxy primers and is suitable in all but themost aggressive environments.

d) Alkyd. This excellent coating system has beenused for many years on original equipment. Alkyd coating canwork in many areas of a WWTP, but not in immersion, high humidityenvironments, or in exposures to strong alkalis, such as sodiumhydroxide or lime.

When selecting coatings, consider the entire system,which includes surface preparation, prime coat, and intermediateand finish coats. Good surface preparation is critical for asuccessful coating application and good performance. However,when dealing with existing surfaces, compromises may be required.

8.2.1.1 Surface Preparation. The preparation of the surface isthe most important variable in good coating performance.Whenever an existing coating system has failed significantly, itis recommended that the surface be cleaned to bare metal.Recoating of an existing painted surface will require cleaning toremove all surface contamination plus roughing of the surface toachieve a good bond of the new coating application.

Excellent guides for surface preparation are availablefrom MIL-HDBK-1110 and the Steel Structures Painting Council(SSPC). Table 13 summarizes the SSPC Surface PreparationStandards. These standards should be followed for all surface

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preparation of metal substrates that are to be painted. Inaddition to surface cleanliness, the surface profile (roughness)must also be specified. Refer to the coating manufacturer’srequirements for the specific profile.

Although the SSPC standards are specifically addressedto steel substrates, some of the standards are commonly used forconcrete substrates. SSPC SP12 specifically is not limited tosteel.

Table 13Surface Preparation Standards

Designation Title Typical UsesSSPC SP1 Solvent Cleaning For all surfacesSSPC SP2 Hand Tool Cleaning Where abrasive blasting

not permittedSSPC SP3 Power Tool Cleaning Where abrasive blasting

not permittedSSPC SP5 White Metal Blast Cleaning For immersion serviceSSPC SP6 Commercial Blast Cleaning Noncritical areasSSPC SP7 Brush-Off Blast Cleaning New concreteSSPC SP8 Pickling For hot dip galvanizedSSPC SP10 Near-White Blast Cleaning Non-immersion, but

critical serviceSSPC SP11 Power Tool to Bare Metal Special, non-immersionSSPC SP12 High- and Ultrahigh-

Pressure Water JettingGeneral clean-up;existing concrete

8.2.1.2 Coating Systems for Metals. Maintenance of coatingsystems in WWTPs depends upon a number of factors: 1) knowingthe specific coating systems that currently exist within theplant; 2) implementing an active inspection program; and3) providing a good maintenance painting program. Maintenancepainting operations are different than new construction paintingoperations. With a proper maintenance painting program, totalrecoating is generally unusual rather than normal.

Inspection of all coating surfaces should be performedroutinely. Be observant for the first signs of coatingbreakdown, such as rust staining and streaking, blistering ofcoating, peeling of coating, and other signs of deterioration.Coatings on steel substrates will generally show the first signsof failure at sharp edges, such as edges of structural steel,adjacent to welds, and around threads of bolts and edges of nuts.Failures on flat surfaces take much longer to develop. Inimmersion service, coating failures also develop first at edges

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but can also develop on flat surfaces because of imperfectionsand defects. Linings in tanks and vessels are especiallycritical.

8.2.1.3 Coating Systems for Concrete. Coating concretesurfaces for merely cosmetic purposes should be discouragedbecause of increased maintenance costs. The coating systems forconcrete surfaces in contact with liquids should be coal-tarepoxy or polyamide epoxy. Maintenance of coating systems onconcrete substrates generally follows the general procedures usedon steel substrates. However, breakdown of coatings on concretecan lead to absorption of the fluids into the concrete substrate,making surface preparation more difficult. In addition, minordefects in the coating do not develop rust staining, as they doon steel substrates. Therefore, it is more critical to maintaina regular inspection program.

Most chemical storage areas will have concretecontainment walls to contain potential spills of the tankcontents. These containment surfaces must be coated with asuitable coating system capable of withstanding the spilledchemical. Most monolithic (bonded) coatings will mirror anycracks that may develop in the concrete. Visually inspect theseareas to detect any leaks of spills through the concrete.

8.2.1.4 Coating Application. High-quality coatings can usuallybe applied using the most common coating techniques:

a) Brush application

b) Roller application

c) Conventional spray application

d) Airless spray application

e) Trowel application (often for floor coatings)

Because most coating systems are complex, the mixingand application of coatings requires considerable experience.It is generally recommended that coating application be left toqualified applicators.

Routine maintenance can be performed before coatingfailures reach the point of requiring major repainting by anoutside contractor. With regular inspection, touch-up of damagedcoatings can be performed using the appropriate, compatible

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coating system. Generally, adequate surface preparation can beaccomplished with power or hand tools (SSPC SP2, SSPC SP3, orSSPC SP11). Surfaces should also be washed to remove any surfacecontamination. Application of touch-up paint can best beaccomplished by brush or roller. The newly applied paint shouldcarry over onto the sound, old painted surfaces. The coatingmanufacturer or his or her representative can providerecommendations and guidelines for mixing and applying thecoatings.

8.2.2 Cathodic Protection. Cathodic protection systems aregenerally provided for all critical equipment. Often thisequipment includes buried pipelines. Cathodic protection mayalso be used on submerged equipment, such as clarifier rakemechanisms. Cathodic protection provides additional corrosionprotection, supplementing the normal protection offered byprotective coating systems. Refer to MIL-HDBK-1004/10.

Cathodic protection systems generally require a certainamount of maintenance to ensure that the systems continue tooperate at design levels. O&M personnel need to be aware of anycathodic protection systems at the WWTP. MIL-HDBK-1136, CathodicProtection Operations and Maintenance, provides specificprocedures that must be followed.

8.2.3 Materials of Construction. Much of a typical WWTPconsists of cast-in-place concrete structures. With a fewexceptions, concrete performs well in the environments associatedwith WWTPs. Other common construction materials also do well butrequire careful selection and maintenance to achieve long-termservice life. The wastewater associated with treatment plants isusually not extremely aggressive, unless the facility receiveswastewater from certain industrial operations. However, hydrogensulfide is everpresent and must be recognized, especially in thevapor areas above the wastewater surface. The wastewater surfaceline in steel tanks is typically one of the first areas to becomesusceptible to corrosion. Where the wastewater is agitated orfalls over weirs, hydrogen sulfide is released. Any condensateformed will be very acidic and therefore aggressive to concreteand unprotected carbon steel.

Perform regular inspection of the concrete and steelsurfaces in these aggressive areas and take appropriate actionwhen significant corrosion becomes evident. Corrosion of metalsurfaces usually occurs faster than on concrete surfaces andcorrective action should be performed as soon as possible. Inthe case of concrete, the application of protective coatings is

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usually required. For metals, use of protective coatings,application of cathodic protection, or replacement with moreresistant metals may be appropriate.

8.2.3.1 Metals. The following metals are used extensivelyin WWTPs:

a) Ductile iron pipe, both lined (cement-mortar) andunlined. Coatings and cathodic protection may or may not berequired.

b) Steel pipe, generally lined with coal-tar epoxy.Buried steel pipe usually requires external coatings,supplemented with cathodic protection.

c) Carbon steel structural. Always requiresprotective coatings.

d) Aluminum used in most atmospheric exposures, suchas ladders, grating, handrails, and covers. Protective coatingsare normally not required.

e) Stainless steels, usually Type 304 or Type 316.If there are high chlorides in the wastewater, Type 316 isusually required. If considerable fabrication is involved,specify the low-carbon (L-grade) stainless steel. Coatings aregenerally not required, unless the steel is buried.

f) Stainless steel fasteners, preferred because aWWTP’s environment is wet and corrosive.

8.2.3.2 Nonmetals. Most nonmetals may be used with success innearly all areas of a WWTP. In addition to concrete, plasticmaterials, such as thermal plastics and thermal-sets, are usedextensively. Such materials as polyvinylchloride (PVC),chlorinated polyvinylchloride (CPVC), polyethylene (PE), andfiberglass-reinforced plastics (FRP) are used in manyapplications.

From a maintenance standpoint, the nonmetallicmaterials require different skills to install, maintain, andrepair. PVC and CPVC are joined with special cements, PE isjoined usually by heat fusion, and FRP is joined with reinforcedresin layup. Maintenance of PVC, CPVC, and FRP can usually beperformed by in-plant crews. Repair of PE requires specialtooling that is not usually available onsite.

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Section 9: Chemical shipping and feeding

9.1 Sources of Information. Process chemicals used inwastewater treatment vary greatly in their specific requirementsfor safe storage and handling. Several industrial associations,including the Chlorine Institute, the National Lime Association,the Manufacturing Chemists Association, and the National FireProtection Association (NFPA) provide information for operators.In addition, chemical manufacturers will supply handbooks andmaterial safety data sheets (MSDSs) for specific processchemicals upon request.

Table 14 provides information about various chemicalscommonly used at WWTPs, including their common names, formulas,and most common uses. It also covers the forms and containers inwhich they are usually obtained commercially and generalcharacteristics of the chemicals. Table 15 presents informationabout feeding these chemicals, including the most common formsfor feeding, the amount of water needed for continuousdissolving, types of feeders, handling equipment, and appropriatematerials for storage and handling.

Table 14Chemical Shipping Data and Characteristics

Chemical Shipping Data Characteristics

Common Name/Formula/Use

Grades orAvailableForms

ContainersandRequirements

AppearanceandProperties

Weightlb/cu ft(BulkDensity)

CommercialStrength

Solubility inWatergm/100 mL1

ALUM: A12(SO4)3•XH2OLiquid1 gal 36°Be = 5.38 lbof dry alum: 60°FCoag. at pH 5.5 to8.0Sludge conditionerPrecipitate PO4

Soln.32.2°Be to37°Be

Manufacturednear site6,000: 8,000 galsteel T/C2,000 to4,000 galrubber-linedsteel tanktrucksHigh freightcost precludesdistant shipment

Light green tolight brownsoln.F.P. orcrystallizationpoint for:35.97°Be = 4°F36.95°Be = 27°F37.7°Be = 60°F1% soln.: pH 3.4Visc. 36°Be at60°F = 25 cp

36°Besp.g. = 1.33or11.1 lb/galat 60°F

At 60°F32.2°Be:7.25% Al2O335.97°Be:8.25% Al2O337°Be:8.5% Al2O3

Completelymiscible

ALUMINUM SULFATE:A12(SO4)3•14H2O(Alum, filter alum)Coagulation at pH 5.5to 8.0Dosage between 0.5 to9 gpgPrecipitate PO4

LumpGranularRiceGroundPowder

Bags: 100 &200 lbBbl.: 325 &400 lbDrums: 25, 100,& 250 lbBulk: C/L

Light tan togray-greenDusty,astringentOnly slightlyhygroscopic1% soln.: pH 3.4

60 to 75(powder islighter)To calculatehoppercapacities,use 60

98% plus or17% Al2O3(minimum)

72.5 at 0°C78.0 at 10°C87.3 at 20°C101.6 at 30°C

AMMONIA ANHYDROUS:NH3(Ammonia)Chlorine-ammoniatreatmentAnaerobic digestionNutrient

Colorlessliquifiedgas

Steel cylinders:50, 100, 150 lbT/C: 50,000 lbGreen gas label

Pungent,irritating odorLiquid causesburnsF.P. is -107.9°FB.P. is -28°Fsp.g. (gas) 0.59at 70°C and1 atmMCA warninglabelVisc. liquid =0.27 cps at 33°C

sp.g. ofliquid is0.68 at-28°F

99 to 100%NH3

89.9 at 0°C68.0 at 10°C57.5 at 20°C47.7 at 30°C

Table 14 (Continued)Chemical Shipping Data and Characteristics

Chemical Shipping Data Characteristics

Common Name/Formula/Use

Grades orAvailableForms

ContainersandRequirements

AppearanceandProperties

Weightlb/cu ft(BulkDensity)

CommercialStrength

Solubility inWatergm/100 mL1

AMMONIA, AQUA: NH4OH(Ammonium hydroxide,ammonia water,ammonium hydrate)Chlorine-ammoniatreatmentpH controlNutrient

TechnicalCertifiedpureSolution16°Be20°Be26°Be

Carboys: 5 &10 galDrums: 375 &750 lbT/C: 8,000 gal

Water whitesoln.StronglyalkalineCauses burnsIrritating vaporUnstable; storein cool placeand tightcontainerMCA warninglabelVent feedingsystems

At 60°F26°BeSp.g. 0.8974

16°Be10.28% NH320°Be17.76% NH326°Be29.4% NH3

Completelymiscible

CALCIUM HYDROXIDE:Ca(OH)2(Hydrated lime,slaked lime)Coagulation,softeningpH adjustmentWaste neutralizationSludge conditioningPrecipitate PO4

LightpowderPowder

Bags: 50 lbBbl: 100 lbBulk: C/L (storein dry place)

White200 to 400 meshpowderFree from lumpsCaustic,irritant, dustySat. soln.:pH 12.4Absorbs H2O andCO2 from air torevert back toCaCO310% slurry: 5 to10 cpsSp.g. = 1.08

20 to 30 and30 to 50To calcu-late hoppercapacity,use 25 or 35

Ca(OH)282 to 95%CaO62 or 72%

0.18 at 0°C0.16 at 20°C0.15 at 30°C

Table 14 (Continued)Chemical Shipping Data and Characteristics

Chemical Shipping Data Characteristics

Common Name/Formula/Use

Grades orAvailableForms

ContainersandRequirements

AppearanceandProperties

Weightlb/cu ft(BulkDensity)

CommercialStrength

Solubility inWatergm/100 mL1

CALCIUM HYPOCHLORITE:Ca(OCl)2•4H2O(H.T.H., Perchloron,Pittchlor)DisinfectionSlime controlDeodorization

GranulesPowderPellets

Bbl: 415 lbCans: 5, 15,100, 300 lbDrums: 800 lb(store dry andcool and avoidcontact withorganic matter)

White oryellowish whiteHygroscopiccorrosiveStrong chlorineodor(Alkaline pH)Yellow label—oxidizing agent

Granules68 to 80Powder32 to 50

70% avail. Cl2 21.88 at 0°C22.7 at 20°C23.4 at 40°C

CALCIUM OXIDE: CaO(Quicklime, burntlime, chemical lime,unslaked lime)CoagulationSofteningpH adjustmentWaste neutralizationSludge conditioningPrecipitate PO4

PebbleLumpGroundPulverizedPelletGranulesCrushed

Moisture-proofbags: 100 lbWood barrelBulk: C/L(store dry: max.60 days and keepcontainerclosed)

White (lightgray, tan) lumpsto powderUnstable,caustic,irritantSlakes tohydroxide slurryevolving heatAir slakes toform CaCO3•sat.Soln. pH is 12.4

55 to 70To calculatehoppercapacity,use 60Pulv. is 43to 65

70 to 96% CaO(below 85%can be poorquality)

Reacts toform CA(OH)2See CA(OH)2above2

CARBON, ACTIVATED: C(Nuchar, Norit,Darco, Carbodur)Decolorizing, tasteand odor removalDosage between 5 and80 ppm

PowderGranules

Bags: 35 lb(3 x 21 x 39 in)Drums: 5 lb &25 lbBulk: C/L

Black powder,about 400 meshDusty, smouldersif ignitedArches inhoppers;floodable3

Do not mix withKMnO4, hypo-chlorite, orCaO; pH varies

Powder8 to 28(avg. 12)

10% C (bonecharcoal) to90% C (woodcharcoal)

Insolubleforms aslurry

Table 14 (Continued)Chemical Shipping Data and Characteristics

Chemical Shipping Data Characteristics

Common Name/Formula/Use

Grades orAvailableForms

ContainersandRequirements

AppearanceandProperties

Weightlb/cu ft(BulkDensity)

CommercialStrength

Solubility inWatergm/100 mL1

CHLORINE: Cl2(Chlorine gas, liquidchlorine)DisinfectionSlime controlTaste and odorcontrolWaste treatmentActivation of silica4

Liquefiedgas underpressure

Steel cylinders:100 & 150 lbTon containersT/C: 15-toncontainersT/C: 16, 30,55 tonsGreen label

Greenish-yellowgas liquefiedunder pressurePungent,noxious,corrosive gasheavier than airHealth hazard

sp.g. withrespect toair = 2.49

99.8% Cl2 0.98 at 10°C0.716 at 20°C0.57 at 30°C

CHLORINE DIOXIDE:ClO2DisinfectionTaste and odorcontrol (especiallyphenol)Waste treatment 0.5to 5 lb NaClO2 permillion gal H2Odosage

Generatedas usedfrom Cl2and NaClO2or fromNaOCl plusacidDissolvedasgenerated

26.3% avail. Cl2 Yellow solutionwhen generatedin waterYellow-red gasUnstable,irritating,poisonous,explosiveKeep cool, keepfrom light

----- Use 2 lb ofNaCl02 to 1 lbof Cl2, orequal conc.of NaClO2 andNaOCl plusacid (max. 2%each plusdiln. water)

0.29 at 21°C

FERRIC CHLORIDE:FeCl3 - anhydrousFeCl3 - 6H2O = crystalFeCl3 - solution(Ferrichlor, chlorideor iron)Coagulation pH 4to 11Dosage: 0.3 to 3 gpg(sludge cond. 1.5 to4.5% FeCl3)Precipitate PO4

SolutionLumps-sticks(crystals)Granules

SolutionCarboys:5, 13 galTruck, T/CCrystalKeg: 100, 400,450 lbDrums: 150, 350,630 lb

SolutionDark brown syrupCrystalsYellow-brownlumpsAnhydrousGreen, blackVery hygro-scopic,staining,corrosive inliquid form1% soln.: pH 2.0

Solution11.2 to12.4 lbCrystal60 to 64Anhydrous45 to 60

Solution35 to 45%FeCl3Crystal60% FeCl3Anhydrous96 to 97%FeCl3

SolutionCompletelymiscibleCrystals91.1 at 20°CAnhydrous74.4 at 0°C

Table 14 (Continued)Chemical Shipping Data and Characteristics

Chemical Shipping Data Characteristics

Common Name/Formula/Use

Grades orAvailableForms

ContainersandRequirements

AppearanceandProperties

Weightlb/cu ft(BulkDensity)

CommercialStrength

Solubility inWatergm/100 mL1

FERRIC SULFATE:Fe2(SO4)3•3H2O(Ferrifloc)Fe2(SO4)3•2H2O(Ferriclear)(Iron sulfate)Coag. pH 4-6 &8.8-9.2Dosage: 0.3 to 3 gpgPrecipitate PO4

Granules Bags: 100 lbDrums: 400 &425 lbBulk: C/L

2H2O, red brown3H2O, red grayCakes at high RHCorrosive insoln.Store dry intight containersStains

70 to 72 3H2O68% Fe2(SO4)318.5% Fe2H2O76% Fe2 (SO4)321% Fe

Very soluble

FERROUS SULFATE:FeSO4•7H2O(Copperas, ironsulfate, sugarsulfate, greenvitroil)Coagulation at pH 8.8to 9.2Chrome reduction inwaste treatmentSewage odor controlPrecipitate PO4

GranulesCrystalsPowderLumps

Bags: 100 lbBbl: 400 lbBulk

Fine greenishcrystalsM.P. is 64°COxidizes inmoist airEfflorescent indry airMasses instorage athigher temp.Soln. is acid

63 to 66 55% FeSO420% Fe

32.8 at 0°C37.5 at 10°C48.5 at 20°C60.2 at 30°C

HYDROGEN PEROXIDE:H2O2Odor control

Soln. 35%& 50%

4,000 and 8,000gal T/C and4,000 T/T

Clear, colorlessliquid at allconcentrationsF.P. for 50% =-40°C

For 35%,sp.g. = 1.13or9.4 lb/galFor 50%,sp.g. =1.20 or10.0 lb/gal

For 35%,396 g/L H2O2or 16.5% O2For 50%,598 g/L H2O2or 23.5% O2

Completelymiscible

METHANOL: CH3•OHWood alcoholdenitrification

Liquid Drums, bulk Clear, colorlessliquid at allconcentrations

For 100%,sp.g. @ 20°C= 0.7917

99% Completelymiscible

Table 14 (Continued)Chemical Shipping Data and Characteristics

Chemical Shipping Data Characteristics

Common Name/Formula/Use

Grades orAvailableForms

ContainersandRequirements

AppearanceandProperties

Weightlb/cu ft(BulkDensity)

CommercialStrength

Solubility inWatergm/100 mL1

OZONE: O3Taste and odorcontrolDisinfectionWaste treatmentOdor: 1 to 5 ppmDisinfection: 0.5 to1 ppm

GasLiquid

Generated atsite by actionof electricdischargethrough dryair: 0.5 to 1%produced

Colorless-bluishgas or blueliquidToxic: do notbreatheExplosiveFire hazardKeep from oil orreadilycombustiblematerials

Density ofgas is2.1 gm/LLiquid sp.g.is 1.71 at-183°C.

1 to 2% 49.4 ccat 0°C

PHOSPHORIC ACID,ORTHO: H3PO4Boiler watersofteningAlkalinity reductionCleaning boilersNutrient feeding

50, 75,85, 90%AnhydrousCommercialTechnicalFoodN.F.

Bottles:1 to 5 lb;5, 6-1/2, 13 galCarboys: 55-galdrums & barrelsTank cars andtrucks

Clear, colorlessliquidF.P. (50%) is35°CB.P. (50%) is108°CpH (0.1N) is 1.515 to 30 cpviscosityaccording to %Avoid skincontactMCA warninglabelCan form H2 withsome metals

50%11.2 lb/gal75%13.3 lb/ gal85%14.1 lb/gal

50, 75, and85% conc.

Liquidmiscible withwater in allproportions

POLYMERS, DRY5

High M.W. syntheticpolymers

Powdered,flakygranules

Multiwall paperbags

White flakepowderpH varies

27 to 35 ---- Colloidalsolution

Table 14 (Continued)Chemical Shipping Data and Characteristics

Chemical Shipping Data Characteristics

Common Name/Formula/Use

Grades orAvailableForms

ContainersandRequirements

AppearanceandProperties

Weightlb/cu ft(BulkDensity)

CommercialStrength

Solubility inWatergm/100 mL1

POLYMERS, LIQUID ANDEMULSIONS5

High M.W. syntheticpolymersSeparan NP10 potablegrade, Magnifloc 990;Purifloc N17 Ave.Dosage: 0.1 to 1 ppm

---- Drums, bulk Viscose liquid Liquid:20 to 5,000cp at 70°FEmulsions:200 to 700cp at 70°F

---- Colloidalsolution

POTASSIUMPERMANGANATE: KMnO4CairoxTaste odor control0.5 to 4.0 ppmRemoves Fe and Mn ata 1-to-1 ratio

Crystal U.S.P.25-,110-,125-lbsteel kegTechnical25-,110-,600-lbsteel drum

Purple crystalssp.g.: 2.7Decomposes 240°CCan cake up athigh relativehumidityStrong oxidantToxicKeep fromorganicsYellow label

86 to 102 Tech. is 97%minimumReagent is99% minimum

2.8 at 0°C3.3 at 10°C5.0 at 20°C7.5 at 30°C

SODIUM ALUMINATE:Na2Al2O4, anhy.(soda alum)Ratio Na2O/Al2O31/1 or 1.15/1 (highpurity)Also Na2A12O4•3H2Ohydrated formCoagulationBoiler H2O treatment

Ground(pulv.)CrystalsLiquid,27°BeHydratedAnhydrous

Ground bags:50-, 100-lbdrumsLiquid drums

High puritywhiteStandard grayHygroscopicAq. soln. isalkalineExothermic heatof solution

High purity50Std. 60

High PurityAl2O3 45%Na2Al2O4 72%StandardAl2O3 55%Na2Al2O4 88 to90%

Hydrated80 at 75°FStd.6 to 8%insolublesAnhy.3/gal at 60°F

Table 14 (Continued)Chemical Shipping Data and Characteristics

Chemical Shipping Data Characteristics

Common Name/Formula/Use

Grades orAvailableForms

ContainersandRequirements

AppearanceandProperties

Weightlb/cu ft(BulkDensity)

CommercialStrength

Solubility inWatergm/100 mL1

SODIUM BICARBONATE:NaHCO3 (baking soda)Activation of silicapH adjustment

U.S.P.C.P.CommercialPurePowderGranules

Bags: 100 lbBbl: 112, 400 lbDrums: 25 lbKegs

White powderSlightlyalkaline1% soln.:pH 8.2Unstable insoln. (de-composes intoCO2 and Na2CO3)Decomposes 100°F

59 to 62 99%NaHCO3

6.9 at 0°C8.2 at 10°C9.6 at 20°C10.0 at 30°C

SODIUM BISULFITE,ANHYDROUS:Na2S2O5 (NaHSO3)(Sodium pyrosulfite,sodium meta-bisulfite)Dechlorination: about1.4 ppm for eachppm C12Reducing agent inwaste treatment(as Cr)

CrystalsCrystalspluspowderSolution(3.25 to44.9%)

Bags: 100 lbDrums: 100 &400 lb

White to slightyellowSulfurous odorSlightlyhygroscopicStore dry intight containerForms NaHSO3 insoln.1% soln.: pH 4.6Vent soln. tanks

74 to 85 and55 to 70

97.5 to 99%Na2S2O5SO2 65.8%

54 at 20°C81 at 100°C

SODIUM CARBONATE:Na2CO3(Soda ash: 58% Na2O)Water softeningpH adjustment

DensegranulesMed. gran.and pwd.Lightpowder

Bags: 100 lbBbl: 100 lbDrums: 25 &100 lbBulk: C/L

White, alkalineHygroscopic: cancake up1% soln.:pH 11.2

Dense 65Medium 40Light 30

99.2% Na2CO358% Na2O

7.0 at 0°C12.5 at 10°C21.5 at 20°C38.8 at 30°C

Table 14 (Continued)Chemical Shipping Data and Characteristics

Chemical Shipping Data Characteristics

Common Name/Formula/Use

Grades orAvailableForms

ContainersandRequirements

AppearanceandProperties

Weightlb/cu ft(BulkDensity)

CommercialStrength

Solubility inWatergm/100 mL1

SODIUM CHLORITE:NaClO2(Technical sodiumchlorite)Disinfection, taste,and odor controlInd. waste treatment(with Cl2 producesClO2)

PowderFlakesCrystals(tech. andanalyt-ical)Soln.(about40%)crystal-lizesabout 95°F

Drums: 100 lb(do not letNaClO2 dry outon combustiblematerials)

Tan or whitecrystals orpowderHygroscopicPoisonousPowerfuloxidizing agentExplosive oncontact withorganic matterStore in metalcontainers onlyOxidizerLiquid:white labelSolid:yellow label

65 to 75 Technical81%78% (minimum)124% avail.Cl2Anal.98.5%153% avail.Cl2

34 at 5°C39 at 17°C46 at 30°C55 at 60°C

SODIUM HYDROXIDE:NaOH(Caustic soda,soda lye)pH adjustment,neutralization

FlakesLumpsPowderSolution

Drums: 25, 50,350, 400, 700 lbBulk: Solutionin T/CLiquidWhite label

White flakes,granules, orpelletsDeliquescent,caustic poisonDangerous tohandle1% soln.:pH 12.950% soln. willcrystallize at54°F

Pellets60 to 70Flakes46 to 62

Solid98.9% NaOH74.76% Na2OSolution12 to 50%NaOH

42 to 0°C51.5 at 10°C109 at 20°C119 at 30°C

Table 14 (Continued)Chemical Shipping Data and Characteristics

Chemical Shipping Data Characteristics

Common Name/Formula/Use

Grades orAvailableForms

ContainersandRequirements

AppearanceandProperties

Weightlb/cu ft(BulkDensity)

CommercialStrength

Solubility inWatergm/100 mL1

SODIUM HYPOCHLORITE:NaOCl(Javelle water,bleach liquor,chlorine bleach)Disinfection, slimecontrolBleaching

SolutionWhite oryellowlabel

Carboys: 5 &13 galDrums: 30 galBulk: 1,300,1,800, 2,000gal %/T

Yellow liquidStronglyalkalineStore in coolplaceProtect fromlight and ventcontainers atintervalsCan be storedabout 60 daysunder properconditions

15%10.2 lb/gal12.5%10 lb/gal

15% NaOCl =1.25 lbCl2/gal12.5% NaOCl =1.04 lbCl2/gal

Completelymiscible

SULFUR DIOXIDE: SO2Dechlorination indisinfectionFilter bed cleaningAbout 1 ppm SO2 foreach ppm Cl2(dechlorination)Waste treatmentCr +6 reduction

Liquifiedgas underpressure

Steel cylinders:100, 150, 200 lbGreen label

Colorless gasSuffocating odorCorrosivePoisonAcid insolution:dissolves toform H2SO3

---- 100% SO2 760 mm22.8 at 0°C16.2 at 10°C11.3 at 20°C7.8 at 30°C

SULFURIC ACID: H2SO4(Oil of Vitriol,Vitriol)pH adjustmentActivation of silicaNeutralization ofalkaline wastes

Liquid66°Be60°Be50°Be

BottlesCarboys:5, 13 galDrums:55, 110 galBulkT/T, T/CWhite label

Syrupy liquidVery corrosiveHygroscopicStore dry andcool in tightcontainerpH: 1.2

66°Be15.1 lb/gal60°Be14.2 lb/gal

66°Be93.2% H2SO460°Be77.7% H2SO450°Be62.2% H2SO4

Completelymiscible

Table 14 (Continued)Chemical Shipping Data and Characteristics

1Solubilities are generally given at four different temperatures stated in degrees Centigrade.Temperature Fahrenheit Equivalent0°C 32°F10°C 50°F20°C 68°F30°C 86°F

2Each pound of CaO will slake to form 1.16 to 1.32 lb of CA(OH)2 (depending on purity) and from 2 to 12% grit.3“Floodable” as used in this table with dry powder means that, under some conditions, the material entrains air and becomes “fluidized” so that it will flow through small openings, like water.4For small doses of chlorine, use calcium hypochlorite or sodium hypochlorite.5Information about many other coagulant aids (or flocculant aids) is available from Nalco, Calgon, Drew, Betz, North American Mogul, American Cyanamid, Dow, etc.anhy. anhydrous gpg grains per gallonaq. aqueous ind. industrialavail. available max. maximumavg. average M.P. melting pointbbl. barrel min. minuteB.P. boiling point M.W. molecular weightC/L carload ppm parts per millioncoag. coagulation / perconc. concentration % percentcc cubic centimeter lb poundcu ft cubic foot lb/gal pounds per gallon°Be degrees Baume(a measurement of solutionconcentration)

pulv. pulverized°C degrees Celsius sat. saturated°F degrees Fahrenheit soln. solutiondiln. dilution sp.g. specific gravityesp. especially std. standardF.P. freezing point T/C tank cargal gallon T/T tank truckgm gram wt. weightin. inch

Source: BIF Technical Bulletin Chemicals Used in Treatment of Water and Wastewater. Tablemodified and reproduced with permission.

Table 15Chemical-Specific Feeding Recommendations

Feeding Recommendations

Common Name/Formula/Use

BestFeedingForm

Chemical-to-Water Ratio forContinuousDissolving1

TypesofFeeders

AccessoryEquipmentRequired

SuitableHandlingMaterials forSolutions2

ALUM: A12(SO4)3•XH2OLiquid1 gal 36°Be = 5.38 lbof dry alum: 60°FCoag. at pH 5.5 to 8.0Sludge conditionerPrecipitate PO4

Full strengthunder controlledtemp. or diluteto avoidcrystallizationMinimize surfaceevap.: causesflow problemsKeep dry alumbelow 50%to avoidcrystallization

Dilute tobetween 3% and15% accordingto applicationconditions,mixing, etc.

SolutionRotodipPlunger pumpDiaphragm pump1700 pumpL-I-W

Tank gauges orscalesTransfer pumpsStorage tankTemperaturecontrolEductors ordissolvers fordilution

Lead orrubber-linedtanks,Duriron, FRP3,Saran, PVC-1,vinyl,Hypalon,Epoxy, 16 ss,Carp. 20 ss,Tyril

ALUMINUM SULFATE:A12(SO4)3•14H2O(Alum, filter alum)Coagulation at pH 5.5to 8.0Dosage between 0.5 to9 gpgPrecipitate PO4

Ground,granular, orricePowder is dusty,arches, and isfloodable4

0.5 lb/galDissolverdetention time5 min. forground (10 min.for granules)

GravimetricBelt L-I-WVolumetricHelixUniversalSolutionPlunger pumpDiaphragm pump1700 pump

DissolverMechanical mixerScales forvolumetric feedersDust collectors

Lead, rubber,FRP3, PVC-1,316 ss, Carp.20 ss, vinyl,HypalonEpoxy,Ni-Resistglass,ceramic,polyethylene,Tyril,Uscolite

AMMONIA ANHYDROUS: NH3(Ammonia)Chlorine-ammoniatreatmentAnaerobic digestionNutrient

Dry gas or asaqueous soln.:see “Ammonia,Aqua”

---- Gas feeder Scales Steel,Ni-Resist,Monel,316 ss,Penton,Neoprene

Table 15 (Continued)Chemical-Specific Feeding Recommendations

Feeding Recommendations

Common Name/Formula/Use

BestFeedingForm

Chemical-to-Water Ratio forContinuousDissolving1

TypesofFeeders

AccessoryEquipmentRequired

SuitableHandlingMaterials forSolutions2

AMMONIA, AQUA: NH4OH(Ammonium hydroxide,ammonia water, ammoniumhydrate)Chlorine-ammoniatreatmentpH controlNutrient

Full strength ---- SolutionL-I-WDiaphragm pumpPlunger pumpBal. diaphragmpump

ScalesDrum handlingequipment orstorage tanksTransfer pumps

Iron, steel,rubber,Hypalon,316 ss, Tyril(room temp.to 28%)

CALCIUM HYDROXIDE:Ca(OH)2(Hydrated lime, slakedlime)Coagulation, softeningpH adjustmentWaste neutralizationSludge conditioningPrecipitate PO4

Finer particlesizes moreefficient, butmore difficultto handle andfeed

Dry feed:0.5 lb/gal max.Slurry:0.93 lb/gal(i.e., a 10%slurry)(Light to a 20%conc. max.)(Heavy to a 25%conc. max.)

GravimetricL-I-WBeltVolumetricHelixUniversalSlurryRotodipDiaphragmPlunger pump5

Hopper agitatorsNon-flood rotorunder largehoppersDust collectors

Rubber hose,iron, steel,concrete,Hypalon,Penton, PVC-1No lead

CALCIUM HYPOCHLORITE:Ca(OCl)2•4H2O(H.T.H., Perchloron,Pittchlor)DisinfectionSlime controlDeodorization

Up to 3% soln.max. (practical)

0.125 lb/galmakes 1% soln.of availableCl2

LiquidDiaphragm pumpBal. diaphragmpumpRotodip

Dissolving tanksin pairs withdrains to draw offsedimentInjection nozzleFoot valve

Ceramic,glass,rubber-linedtanks, PVC-1,Penton, Tyril(rm. temp.),Hypalon,vinyl, Usco-lite (rm.temp), Saran,Hastelloy C(good).No tin.

Table 15 (Continued)Chemical-Specific Feeding Recommendations

Feeding Recommendations

Common Name/Formula/Use

BestFeedingForm

Chemical-to-Water Ratio forContinuousDissolving1

TypesofFeeders

AccessoryEquipmentRequired

SuitableHandlingMaterials forSolutions2

CALCIUM OXIDE: CaO(Quicklime, burnt lime,chemical lime, unslakedlime)CoagulationSofteningpH adjustmentWaste neutralizationSludge conditioningPrecipitate PO4

1/4 to 3/4 in.pebble limePelletsGround limearches and isfloodablePulv. will archand is floodableSoft burned,porous best forslaking

2.1 lb/gal(range from 1.4to 3.3 lb/galaccording toslaker, etc.)Dilute afterslaking to0.93 lb/gal(10%) max.slurry

GravimetricBeltL-I-WVolumetricUniversalHelix

Hopper agitatorand non-floodrotor for groundand pulv. limeRecordingthermometerWater proportionerLime slakerHigh temperaturesafety cut-out andalarm

Rubber, iron,steel,concrete,Hypalon,Penton, PVC-1

CARBON, ACTIVATED: C(Nuchar, Norit, Darco,Carbodur)Decolorizing, taste andodor removalDosage between 5 and80 ppm

Powder: withbulk density of12 lb/cu ftSlurry: 1 lb/gal

According toits bulkinessand wetability,a 10 to 15%solution wouldbe the max.concen.

GravimetricL-I-WVolumetricHelixRotolockSlurryRotodipDiaphragm pumps

Washdown-typewetting tankVortex mixerHopper agitatorsNon-flood rotorsDust collectorsLarge storage cap.for liquid feedTank agitatorsTransfer pumps

316 ss,rubber,bronze,Monel,Hastelloy C,FRP3, Saran,Hypalon

Table 15 (Continued)Chemical-Specific Feeding Recommendations

Feeding Recommendations

Common Name/Formula/Use

BestFeedingForm

Chemical-to-Water Ratio forContinuousDissolving1

TypesofFeeders

AccessoryEquipmentRequired

SuitableHandlingMaterials forSolutions2

CHLORINE: Cl2(Chlorine gas, liquidchlorine)DisinfectionSlime controlTaste and odor controlWaste treatmentActivation of silica6

Gas: vaporizedfrom liquid

1 lb to45-50 galor more

Gas chlorinator Vaporizers forhigh capacitiesScalesGas masksResidual analyzer

Anhy. liquidor gas:Steel,copper, blackironWet gas:Penton,Viton,Hastelloy C,PVC-1 (good),silver,TantalumChlorinatedH2O: Saran,stoneware,Carp. 20 ss,Hastelloy C,PVC-1, Viton,Uscolite,Penton

CHLORINE DIOXIDE: ClO2DisinfectionTaste and odor control(especially phenol)Waste treatment 0.5 to5 lb NaClO2 per milliongal H2O dosage

Solution fromgeneratorMix dischargefrom chlorinizerand NaClO2solution or addacid to mixtureof NaClO2 andNaOCl. Use equalconcentrations:2% max.

Chlorine watermust contain500 ppm or overof Cl2 and havea pH of 3.5 orlessWater usedepends onmethod ofpreparation

SolutionDiaphragm pump

Dissolving tanksor crocksGas mask

For solutionswith 3% ClO2:Ceramic,glass,Hypalon,PVC-1, Saran,vinyl,Penton,Teflon

Table 15 (Continued)Chemical-Specific Feeding Recommendations

Feeding Recommendations

Common Name/Formula/Use

BestFeedingForm

Chemical-to-Water Ratio forContinuousDissolving1

TypesofFeeders

AccessoryEquipmentRequired

SuitableHandlingMaterials forSolutions2

FERRIC CHLORIDE:FeCl3 - anhydrousFeCl3 - 6H2O = crystalFeCl3 - solution(Ferrichlor, chlorideor iron)Coagulation pH 4 to 11Dosage: 0.3 to 3 gpg(sludge cond. 1.5 to4.5% FeCl3)Precipitate PO4

Solution or anydilution up to45% FECl3content (anhy.form has a highheat of soln.)

Anhy. to form:45%: 5.59 lb/gal40%: 4.75 lb/gal35%: 3.96 lb/gal30%: 3.24 lb/gal20%: 1.98 lb/gal10%: .91 lb/gal(Multiply FeCl3,by 1.666 toobtain FeCl3•6H2Oat 20°C)

SolutionDiaphragm pumpRotodipBal. diaphragmpump

Storage tanks forliquidDissolving tanksfor lumps orgranules

Rubber,glass,ceramics,Hypalon,Saran, PVC-1,Penton, FRP3,vinyl, Epoxy,Hastelloy C(good tofair), Usco-lite, Tyril(Rm)

FERRIC SULFATE:Fe2(SO4)3•3H2O(Ferrifloc)Fe2(SO4)3•2H2O(Ferriclear)(Iron sulfate)Coag. pH 4-6 & 8.8-9.2Dosage: 0.3 to 3 gpgPrecipitate PO4

Granules 2 lb/gal (range)1.4 to 2.4lb/gal for 20min. detention(warm waterpermits shorterdetention)Water insolublescan be high

GravimetricL-I-WVolumetricHelixUniversalSolutionDiaphragm pumpBal. diaphragmpumpPlunger pumpRotodip

Dissolver withmotor-driven mixerand water controlVapor removersolution tank

316 ss,rubber,glass,ceramics,hypalon,Saran, PVC-1,vinyl, Carp.20 ss,Penton, FRP3,Epoxy, Tyril

FERROUS SULFATE:FeSO4•7H2O(Copperas, ironsulfate, sugar sulfate,green vitroil)Coag. at pH 8.8 to 9.2Chrome reduction inwaste treatmentSewage odor controlPrecipitate PO4

Granules 0.5 lb/gal(dissolverdetention time5 min. minimum)

GravimetricL-I-WVolumetricHelixUniversalSolutionDiaphragm pumpPlunger pumpBal. diaphragmpump

DissolversScales

Rubber, FRP3,PVC-1, vinyl,Penton,Epoxy,Hypalon,Uscolite,ceramic,Carp. 20 ss,Tyril

Table 15 (Continued)Chemical-Specific Feeding Recommendations

Feeding Recommendations

Common Name/Formula/Use

BestFeedingForm

Chemical-to-Water Ratio forContinuousDissolving1

TypesofFeeders

AccessoryEquipmentRequired

SuitableHandlingMaterials forSolutions2

HYDROGEN PEROXIDE: H2O2Odor control

Full strength orany dilution

---- Diaphragm pumpPlunger pump

Storage tank,water metering andfiltration devicefor dilution

Aluminum,Hastelloy C,titanium,Viton, Kel-F,PTFE, CPVC

METHANOL: CH3•OHWood alcoholdenitrification

Full strength orany dilution

---- Gear pumpDiaphragm pump

Storage tank 304 ss,316 ss,brass,bronze,Carpenter 20,cast iron,Hastelloy C,buna N, EPDM,Hypalon,naturalrubber, PTFE,PVDF, NORYL,Delrin, CPVC

OZONE: O3Taste and odor controlDisinfectionWaste treatmentOdor: 1 to 5 ppmDisinfection: 0.5 to1 ppm

As generatedApprox. 1% ozonein air

Gas diffused inwater undertreatment

Ozonator Air-dryingequipmentDiffusers

Glass,316 ss,ceramics,aluminum,Teflon

PHOSPHORIC ACID, ORTHO:H3PO4Boiler water softeningAlkalinity reductionCleaning boilersNutrient feeding

50 to 75% conc.(85% is syrupy;100% iscrystalline)

---- LiquidDiaphragm pumpBal. diaphragmpumpPlunger pump

Rubber gloves 316 St.(no F),Penton,rubber, FRP3,PVC-1,Hypalon,Viton,Carp. 20 ss,Hastelloy C

Table 15 (Continued)Chemical-Specific Feeding Recommendations

Feeding Recommendations

Common Name/Formula/Use

BestFeedingForm

Chemical-to-Water Ratio forContinuousDissolving1

TypesofFeeders

AccessoryEquipmentRequired

SuitableHandlingMaterials forSolutions2

POLYMERS, DRY7

High M.W. syntheticpolymers

Powdered,flattishgranules

Max. conc. 1%Feed evenstream tovigorous vortex(mixing toofast willretardcolloidalgrowth)1 to 2 hoursdetention

GravimetricL-I-WVolumetricHelixSolution(Colloidal)Diaphragm pumpPlunger pumpBal. diaphragmpump

Special dispersingprocedureMixer: may hangup; vibrate ifneeded

Steel,rubber,Hypalon,TyrilNoncorrosive,but no zincSame as forH2O of similarpH oraccording toits pH

POLYMERS, LIQUID ANDEMULSIONS7

High M.W. syntheticpolymersSeparan NP10 potablegrade, Magnifloc 990;Purifloc N17 Ave.Dosage: 0.1 to 1 ppm

Makedown to:Liquid:0.5% to 5%Emulsions:0.05% to 0.2%

Varies withcharge type

Diaphragm pumpPlunger pumpBal. diaphragmpump

Mixing and aqueoustanks may berequired

Same as dryproducts

POTASSIUM PERMANGANATE:KMnO4CairoxTaste odor control0.5 to 4.0 ppmRemoves Fe and Mn at a1-to-1 ratio

Crystals plusanticakingadditive

1.0% conc.(2.0% max.)

GravimetricL-I-WVolumetricHelixSolutionDiaphragm pumpPlunger pumpBal. diaphragmpump

Dissolving tankMixerMechanical

Steel, iron(neutral &alkaline)316 st.PVC-1, FRP3,Hypalon,Penton,Lucite,rubber(alkaline)

Table 15 (Continued)Chemical-Specific Feeding Recommendations

Feeding Recommendations

Common Name/Formula/Use

BestFeedingForm

Chemical-to-Water Ratio forContinuousDissolving1

TypesofFeeders

AccessoryEquipmentRequired

SuitableHandlingMaterials forSolutions2

SODIUM ALUMINATE:Na2Al2O4, anhy.(soda alum)Ratio Na2O/Al2O31/1 or 1.15/1 (highpurity)Also Na2A12O4•3H2Ohydrated formCoagulationBoiler H2O treatment

Granular orsoln. asreceivedStd. gradeproduces sludgeon dissolving

Dry 0.5 lb/galSoln. dilute asdesired

GravimetricL-I-WVolumetricHelixUniversalSolutionRotodipDiaphragm pumpPlunger pump

Hopper agitatorsfor dry form

Iron, steel,rubber, 316st. s.,Penton,concrete,Hypalon

SODIUM BICARBONATE:NaHCO3 (baking soda)Activation of silicapH adjustment

Granules orpowder plus TCP(0.4%)

0.3 lb/gal GravimetricL-I-WBeltVolumetricHelixUniversalSolutionRotodipDiaphragm pumpPlunger pump

Hopper agitatorsand non-floodrotor for powder,if large storagehopper

Iron & steel(dilutesolns.:caution),rubber,Saran, st.steel,Hypalon,Tyril

SODIUM BISULFITE,ANHYDROUS:Na2S2O5 (NaHSO3)(Sodium pyrosulfite,sodium meta-bisulfite)Dechlorination: about1.4 ppm for eachppm C12Reducing agent in wastetreatment(as Cr)

Crystals (do notlet set)Storagedifficult

0.5 lb/gal GravimetricL-I-WVolumetricHelixUniversalSolutionRotodipDiaphragm pumpPlunger pumpBal. diaphragmpump

Hopper agitatorsfor powderedgradesVent dissolver tooutside

Glass, carp.20 ss,PVC-1,Penton,Uscolite,316 st., FRP3,Tyril,Hypalon

Table 15 (Continued)Chemical-Specific Feeding Recommendations

Feeding Recommendations

Common Name/Formula/Use

BestFeedingForm

Chemical-to-Water Ratio forContinuousDissolving1

TypesofFeeders

AccessoryEquipmentRequired

SuitableHandlingMaterials forSolutions2

SODIUM CARBONATE:Na2CO3(Soda ash: 58% Na2O)Water softeningpH adjustment

Dense Dry feed0.25 lb/gal for10 min.detention time,0.5 lb/gal for20 min.Soln. feed1.0 lb/galWarm H2O and/orefficientmixing canreducedetention timeif mat. has notsat around toolong and formedlumps—to 5 min.

GravimetricL-I-WVolumetricHelixSolutionDiaphragm pumpBal. diaphragmpumpRotodipPlunger pump

Rotolock for lightforms to preventfloodingLarge dissolversBin agitators formedium or lightgrades and verylight grades

Iron, steel,rubber,Hypalon,Tyril

SODIUM CHLORITE: NaClO2(Technical sodiumchlorite)Disinfection, taste,and odor controlInd. waste treatment(with Cl2 produces ClO2)

Soln. asreceived

Batch solns.0.12 to2 lb/gal

SolutionDiaphragmRotodip

Chlorine feederand chlorinedioxide generator

Penton,glass, Saran,PVC-1, vinyl,Tygon, FRP3,Hastelloy C(fair),Hypalon,Tyril

SODIUM HYDROXIDE: NaOH(Caustic soda,soda lye)pH adjustment,neutralization

Solution feed NaOH has a highheat of soln.

SolutionPlunger pumpDiaphragm pumpBal. diaphragmpumpRotodip

GogglesRubber glovesAprons

Cast iron,steelFor nocontam., usePenton,rubber,PVC-1,316 st.,Hypalon

Table 15 (Continued)Chemical-Specific Feeding Recommendations

Feeding Recommendations

Common Name/Formula/Use

BestFeedingForm

Chemical-to-Water Ratio forContinuousDissolving1

TypesofFeeders

AccessoryEquipmentRequired

SuitableHandlingMaterials forSolutions2

SODIUM HYPOCHLORITE:NaOCl(Javelle water, bleachliquor, chlorinebleach)Disinfection, slimecontrolBleaching

Solution up to16%Available Cl2conc.

1.0 gal of12.5% (avail.Cl2) soln. to12.5 gal ofwater gives a1% avail. Cl2soln.

SolutionDiaphragm pumpRotodipBal. diaphragmpump

Solution tanksFoot valvesWater metersInjection nozzles

Rubber,glass, Tyril,Saran, PVC-1,vinyl,Hastelloy C,Hypalon

SULFUR DIOXIDE: SO2Dechlorination indisinfectionFilter bed cleaningAbout 1 ppm SO2 for eachppm Cl2 (dechlorination)Waste treatmentCr +6 reduction

Gas ---- GasRotameterSO2 feeder

Gas mask Wet gas:Glass,Carp. 20 ss,PVC-1,Penton,ceramics,316 (G),Viton,Hypalon

SULFURIC ACID: H2SO4(Oil of Vitriol,Vitriol)pH adjustmentActivation of silicaNeutralization ofalkaline wastes

Soln. at desireddilutionH2SO4 has a highheat of soln.

Dilute to anydesired conc.:NEVER add waterto acid butrather alwaysadd acid towater.

LiquidPlunger pumpDiaphragm pumpBal. diaphragmpumpRotodip

GogglesRubber glovesApronsDilution tanks

Conc.>85%:Steel, iron,Penton, PVC-1(good), Viton40 to 85%:Carp. 20,PVC-1,Penton, Viton2 to 40%:Carp. 20,FRP3, glass,PVC-1, Viton

Table 15 (Continued)Chemical-Specific Feeding Recommendations

1To convert gm/100 mL to lb/gal, multiply figure (for gm/100 mL) by 0.083. Recommended strengths of solutions for feeding purposes are given in pounds of chemical per gallon of water (lb/gal) and are based on plant practice for the commercial product.The following table shows the number of pounds of chemical to add to 1 gallon of water to obtain various percent solutions:% Soln. lb/gal % Soln. lb/gal % Soln. lb/gal0.1 0.008 2.0 0.170 10.0 0.9270.2 0.017 3.0 0.258 15.0 1.4730.5 0.042 5.0 0.440 20.0 2.2001.0 0.084 6.0 0.533 25.0 2.76030.0 3.5602Iron and steel can be used with chemicals in the dry state unless the chemical is deliquescent or veryhygroscopic, or in a dampish form and is corrosive to some degree.3FRP, in every case, refers to the chemically resistant grade (bisphenol A+) of fiberglass reinforced plastic.4“Floodable” as used in this table with dry powder means that, under some conditions, the material entrains air and becomes “fluidized” so that it will flow through small openings, like water.5When feeding rates exceed 100 lb/hr, economic factors may dictate use of calcium oxide (quicklime).6For small doses of chlorine, use calcium hypochlorite or sodium hypochlorite.7Information about many other coagulant aids (or flocculant aids) is available from Nalco, Calgon, Drew, Betz,North American Mogul, American Cyanamid, Dow, etc.anhy. anhydrous in. inchapprox. approximate ind. industrialaq. aqueous L-I-W loss in weightavail. available max. maximumavg. average M.P. melting pointbbl. barrel min. minuteB.P. boiling point M.W. molecular weightC/l carload ppm parts per millioncoag. coagulation / perconc. concentration % percentcc cubic centimeter lb poundcu ft cubic foot lb/gal pounds per gallonCVPC chlorinated polyvinylchloride Proportioner proportioning pump°Be degrees Baume (a measurement of solution concentration) pulv. pulverized°C degrees Celsius PVC polyvinyl chloride°F degrees Fahrenheit sat. saturateddiln. dilution soln. solutionesp. especially sp.g. specific gravityF.P. freezing point std. standardFRP fiberglass reinforced plastic T/C tank cargal gallon T/T tank truckgm gram wt. weightSource: BIF Technical Bulletin Chemicals Used in Treatment of Water and Wastewater. Table modified and reproduced withpermission.

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APPENDIX ASACRAMENTO SERIES TRAINING MANUAL CONTENTS

Operation of Wastewater Treatment Plants, Volume I1 The Treatment Plant Operator2 Why Treat Wastes?3 Wastewater Treatment Facilities4 Racks, Screens, Comminutors and Grit Removal5 Sedimentation and Flotation6 Trickling Filters7 Rotating Biological Contactors8 Activated Sludge (Package Plants and Oxidation Ditches)9 Waste Treatment Ponds10 Disinfection and Chlorination

Operation of Wastewater Treatment Plants, Volume II11 Activated Sludge (Conventional Activated Sludge Plants)12 Sludge Digestion and Solids Handling13 Effluent Disposal14 Plant Safety and Good Housekeeping15 Maintenance16 Laboratory Procedures and Chemistry17 Applications of Computers for Plant O&M18 Analysis and Presentation of Data19 Records and Report Writing

Operation and Maintenance of Wastewater Collection Systems,Volume I1 The Wastewater Collection System Operator2 Why Collection System Operation and Maintenance?3 Wastewater Collection Systems (Purpose, Components,

and Design)4 Safe Procedures5 Inspecting and Testing Collection Systems6 Pipeline Cleaning and Maintenance Methods7 Underground Repair

Operation and Maintenance of Wastewater Collection Systems,Volume II8 Lift Stations9 Equipment Maintenance10 Sewer Rehabilitation11 Safety/Survival Programs for Collection System

Operators12 Administration13 Organization for System Operation and Maintenance

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APPENDIX A (Continued)

Industrial Waste Treatment, Volume I1 The Industrial Plant Operator2 Safety3 Regulatory Requirements4 Preventing and Minimizing Wastes at the Source5 Industrial Wastewaters6 Flow Measurement7 Preliminary Treatment (Equalization, Screening, and

pH Adjustment)8 Physical-Chemical Treatment Processes (Coagulation,

Flocculation and Sedimentation)9 Filtration10 Physical Treatment Processes (Air Stripping and Carbon

Adsorption)11 Treatment of Metal Wastestreams12 Instrumentation

Industrial Waste Treatment, Volume II1 The Industrial Plant Operator2 Fixed Growth Processes (Trickling Filters and Rotating

Biological Contactors)3 Activated Sludge Process Control4 Sequencing Batch Reactors5 Enhanced Biological Treatment6 Anaerobic Treatment7 Residual Solids Management8 Maintenance

Advanced Waste Treatment1 Odor Control2 Activated Sludge (Pure Oxygen Plants and Operational

Control Options)3 Residual Solids Management4 Solids Removal from Secondary Effluents5 Phosphorus Removal6 Nitrogen Removal7 Enhanced Biological (Nutrient) Control8 Wastewater Reclamation9 Instrumentation

Treatment of Metal Wastestreams1 Need for Treatment2 Sources of Wastewater3 Material Safety Data Sheets (MSDSs)4 Employee Right-to-Know Laws

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APPENDIX A (Continued)

5 Methods of Treatment6 Sludge Treatment and Disposal7 Operation, Maintenance and Troubleshooting

Pretreatment Facility Inspection1 The Pretreatment Facility Inspector2 Pretreatment Program Administration3 Development and Application of Regulations4 Inspection of a Typical Industry5 Safety in Pretreatment Inspection and Sampling Work6 Sampling Procedures for Wastewater7 Wastewater Flow Monitoring8 Industrial Wastewaters9 Pretreatment Technology (Source Control)10 Industrial Inspection Procedures11 Emergency Response

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APPENDIX BSacramento Series Cross Reference List

Contents Item

WastewaterTreatmentSystem

Operations andMaintenanceAugmentingHandbook Sacramento Series

Glossary of Terms @ End ofVolume

Each Manual in Series

General O&M TopicsAnalysis andPresentation of Data

OWTP, Vol. 2, Chapter18

Records and Reports OWTP, Vol. 2, Chapter19

RegulatoryCompliance/Mgmt.

Section 2 IWT Vol. 1, Chapter 3

Computerized O&M OWT Vol. 2, Chapter 17Collection Systems O&MSafety O&MWCS Vol. 1, Chapter

4Inspection and Testing O&MWCS Vol. 1, Chapter

5Pipeline Maintenance O&MWCS Vol. 1, Chapter

5Lift StationMaintenance

O&MWCS Vol. 1, Chapters8, 9

Odor Control inCollection Systems

O&MWCS Vol. 1, Chapter6

Grease Traps Section 4 O&MWCS Vol. 1, Chapter6

Treatment OperationsFacultative Lagoons OWTP Vol. 1, Chapter 9Imhoff Tanks OWTP Vol. 1, Chapter 5Septic Tanks Section 3Preliminary Treatment

Screenings Process OWTP Vol. 1, Chapter 4Comminutors OWTP Vol. 1, Chapter 4Grit Removal OWTP Vol. 1, Chapter 4Flow Equalization OWTP Vol. 1, Chapter 7

Septage Management Section 6Primary Treatment

Sedimentation OWTP Vol. 1, Chapter 5Secondary (Biological)Treatment

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APPENDIX BSacramento Series Cross Reference List

Contents Item

WastewaterTreatmentSystem

Operations andMaintenanceAugmentingHandbook Sacramento Series

Overview of Activated Sludge

OWTP Vol. 2, Chapter 11

Conventional Activated Sludge

OWTP Vol. 2, Chapter 11

Extended Aeration OWTP Vol. 2, Chapter 11Contact Stabilization

OWTP Vol. 2, Chapter 11

Step Feed OWTP Vol. 2, Chapter 11Package Plants OWTP Vol. 1, Chapter 8Oxidation Ditches OWTP Vol. 1, Chapter 8Trickling Filters OWTP Vol. 1, Chapter 6Rotating BiologicalContactors

OWTP Vol. 1, Chapter 7

Sequencing Batch Reactors

AWT, Chapter 7

Aerated Stabilization Basins

OWTP Vol. 1, Chapter 9

Anaerobic Stabilization Ponds

OWTP Vol. 1, Chapter 9

Advanced BiologicalTreatment

Nitrogen Removal AWT, Chapter 6Phosphorous Removal AWT, Chapter 5Combined N/P Removal

AWT, Chapter 7

Tertiary WasteTreatment

Suspended Solids Removal

AWT, Chapter 4

Chemical Phosphorous Removal

AWT, Chapter 5

Activated Carbon Treatment

IWT, Chapter 10

Membrane Filtration IWT, Chapter 9Disinfection

Chlorination OWTP Vol. 1, Chapter 10UV Disinfection OWTP Vol. 1, Appendix

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APPENDIX BSacramento Series Cross Reference List

Contents Item

WastewaterTreatmentSystem

Operations andMaintenanceAugmentingHandbook Sacramento Series

Effluent Disposal andReuse

Discharge to Surface Waters

Section 2 OWTP Vol. 2, Chapter 13

Irrigation Section 2 AWT, Chapter 8Rapid Infiltration Basins

AWT, Chapter 8

Underground Disposal

Section 2

Extreme Climate O&M Section 7Industrial Waste TreatmentIndustrial Waste Monitoring

IWT Vol. 1, Chapters 4,5, 6

Acceptable Wastewater Characteristics forBiological Treatment

IWT Vol. 1, Chapter 5

Waste Minimization IWT Vol. 1, Chapter 4Industrial WastePretreatment

Equalization/Diversion

IWT Vol. 1, Chapter 7

Oil/Water Separators

Section 5

Flotation IWT Vol. 1, Chapter 4Neutralization IWT Vol. 1, Chapter 4Precipitation IWT Vol. 1, Chapter 4Air Stripping IWT Vol. 1, Chapter 4Carbon Adsorption IWT Vol. 1, Chapter 4

Solids Handling andDisposal

Solids Characterization

AWT, Chapter 3

Solids Pumping OWTP Vol. 2, Chapter 12Solids Thickening AWT, Chapter 3Anaerobic Digestion AWT, Chapter 3, OWTP

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APPENDIX BSacramento Series Cross Reference List

Contents Item

WastewaterTreatmentSystem

Operations andMaintenanceAugmentingHandbook Sacramento Series

Vol.2, Chapter 12Aerobic Digestion AWT, Chapter 3, OWTP

Vol.2, Chapter 12Lime Stabilization AWT, Chapter 3Composting AWT, Chapter 3Solids Dewatering AWT, Chapter 3, OWTP

Vol.2, Chapter 12Drying Beds AWT, Chapter 3, OWTP

Vol.2, Chapter 12Solids Disposal AWT, Chapter 3, OWTP

Vol.2, Chapter 12Flow Measurement OWTP Vol.1, Chapter 3Odors and Odor Controlat WWTPs

AWT, Chapter 1

Laboratory ProceduresLaboratory Samplingand Testing

OWTP Vol. 2, Chapter 16

Laboratory ControlTests

OWTP Vol. 2, Chapter 16

Record Keeping OWTP Vol. 2, Chapter 16Plant Safety OWTP Vol. 2, Chapter 14

Identification of Hazards

Included in eachchapter

Protective Equipment

Included in eachchapter

First Aid Included in eachchapter

MaintenanceMaintenance Planningand Scheduling

Included in eachchapter

Preventive Maintenance Included in eachchapter

Equipment Maintenanceand Repair

Included in eachchapter

Instrumentation IWT Vol. 1, Chapter 12AWT, Chapter9

Mechanical EquipmentPumps OWTP Vol. 2, Chapter 15

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APPENDIX BSacramento Series Cross Reference List

Contents Item

WastewaterTreatmentSystem

Operations andMaintenanceAugmentingHandbook Sacramento Series

OMWCS Vol. 2, Chapters8, 9

Valves OWTP Vol. 2, Chapter 15OMWCS Vol. 2, Chapter 8

Motors OWTP Vol. 2, Chapter 15OMWCS Vol. 2, Chapter 9

Couplings and DriveMechanisms

OWTP Vol. 2, Chapter 15OMWCS Vol. 2, Chapters8, 9

Plant Checklist Throughout each manualCorrosion Control Section 8 AWT, Chapter 2Chemical Storage andFeeding

Section 9

Emergency Planning OWTP Vol. 2, Chapter 14OMWCS Vol. 1, Chapter 4OMWCS Vol. 2, Chapter11

Index At the end ofmanual

At the end of eachmanual

OWTP Operation of Wastewater Treatment Plants

OMWCS Operation and Maintenance of Wastewater Collection Systems

IWT Industrial Waste Treatment

AWT Advanced Waste Treatment

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APPENDIX CWWTP OPERATOR CERTIFICATION CONTACT LIST

Association of Boards of Certification208 Fifth StreetAmes, Iowa 50010-6259Telephone: 515-232-3623Fax: 515-232-3778E-mail: amesabc@aol.com

Kenneth D. KerriOffice of Water ProgramsCalifornia State University, Sacramento6000 J StreetSacramento, California 95819-6025Telephone: 916-278-6142E-mail: wateroffice@csus.eduWeb Site: http://www.owp.csus.edu

Water Environment Federation601 Wythe StreetAlexandria, Virginia 22314-1994Telephone: 703-684-2400 or 800-666-0206Fax: 703-684-2492E-mail: msc@wef.orgWeb Site: http://www.wef.org

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BIBLIOGRAPHY

Florida Septic Tank Association. The Magic Box. Lakeland,Florida: Florida Septic Tank Association. 1988.

State of Florida Department of Health and RehabilitativeServices. Chapter 10D-6, Florida Administrative Code, Standardsfor Onsite Sewage Treatment and Disposal Systems, effectiveJanuary 3, 1995.

Cold Climate Sewage Lagoons. Report EPS 3/NR 1. Proceedings ofthe June 1985 Workshop in Winnepeg, Manitoba, Environment Canada.April 1987.

Sewage Lagoons in Cold Climates. Report EPS 4/NR/1. EnvironmentCanada. March 1985.

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REFERENCES

NOTE: THE FOLLOWING REFERENCED DOCUMENTS FORM A PART OF THISHANDBOOK TO THE EXTENT SPECIFIED HEREIN. USERS OF THIS HANDBOOKSHOULD REFER TO THE LATEST REVISIONS OF CITED DOCUMENTS UNLESSOTHERWISE DIRECTED.

FEDERAL/MILITARY SPECIFICATIONS, STANDARDS, BULLETINS, HANDBOOKS,AND NAVFAC GUIDE SPECIFICATIONS:

Unless otherwise indicated, copies are available from the NavalPublishing and Printing Service Office (NPPSO), StandardizationDocument Order Desk, Building 4D, 700 Robbins Avenue,Philadelphia, PA 19111-5094.

MIL-HDBK-1004/10 Electrical Engineering CathodicProtection

MIL-HDBK-1005/9 Industrial and Oily WastewaterControl

MIL-HDBK-1110 Paints and Protective Coatings forFacilities

MIL-HDBK-1136 Cathodic Protection Operations andMaintenance

MIL-HDBK-353 Planning and Commissioning ofWastewater Treatment Plants

ETL 1110-3-466 Selection of Design of Oil andWater Separators (Department ofArmy, U.S. Army Corps of Engineers,Washington, D.C. 20314-1000)

OTHER GOVERNMENT DOCUMENTS AND PUBLICATIONS:EPA/625/R-92/013 Environmental Regulations and

Technology: Control of Pathogensand Vector Attraction in SewageSludge (Including DomesticSeptage) Under 40 CFR Part 503

EPA-625/6-84-009 Septage Treatment and DisposalHandbook (Cincinnati, Ohio: U.S.Environmental Protection Agency,October 1984)

U.S. Army CRRELSpecial Report 85-11

Prevention of Freezing and OtherCold Weather Problems atWastewater Treatment Facilities(Reed et al., Hanover,New Hampshire: U.S. ArmyCRREL, July 1985)

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HQ USAF/CE Oil/Water Separator: Operations,Maintenance and ConstructionMemorandum (October 21, 1994)

HQ AFCEE Oil/Water Separator: ProAct FactSheet. Web address:http:/www.afces.brooks.af.mil/pro_act/main/proact4.htm (December1996)

HQ AFCEE Proper Operation of Maintenance ofOil/Water Separators. (undated)

CALIFORNIA STATE UNIVERSITY

Operation of Wastewater Treatment Plants, Volume 1

Operation of Wastewater Treatment Plants, Volume 2

Operation and Maintenance of Wastewater Collection Systems, Volume 1

Operation and Maintenance of Wastewater Collection Systems, Volume 2

Industrial Waste Treatment, Volume 1

ndustrial Waste Treatment, Volume 2

Advanced Waste Treatment

Treatment of Metal Wastestreams

Pretreatment Facility Inspection

(Available from California State University, 6000 J Street,Sacramento, California 95819-6025.)

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STEEL STRUCTURES PAINTING COUNCIL (SSPC)

SSPC SP1 Solvent CleaningSSPC SP2 Hand Tool CleaningSSPC SP3 Power Tool CleaningSSPC SP5 White Metal Blast CleaningSSPC SP6 Commercial Blast CleaningSSPC SP7 Brush-Off Blast CleaningSSPC SP8 PicklingSSPC SP10 Near-White Blast CleaningSSPC SP11 Power Tool to Bare MetalSSPC SP12 High- and Ultrahigh-Pressure

Water Jetting

(Available from SSPC, 40 24th Street, 6th Floor, Pittsburgh,Pennsylvania 15222-4643.)

AUTHORED PUBLICATIONS:Aldridge, Thomas. “What is an oil/water separator and why do Ineed one”? Pollution Equipment News. December 1996.

Laak, Rein. Wastewater Engineering Design for Unsewered Areas.Lancaster, Pennsylvania: Technomic Publishing Co., Inc.: 1986.

OTHER PUBLICATIONS:National Small Flows Clearing House. Pipeline: Maintaining YourSeptic System: A Guide for Homeowners. Morgantown, WestVirginia: National Small Flows Clearing House. 1995.

API Publication 421. Design and Operation of Oil/WaterSeparators: American Petroleum Institute (1220 L Street,Northwest, Washington, D.C. 22005): February 1990.

B/F Technical Bulletin. Chemicals used in Treatment of Water andWastewater Providence. Rhode Island. May 1970.

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GLOSSARY

AbbreviationOrAcronym Definition

ABC Association of Boards of Certification

AC alternating current

API American Petroleum Institute

BMP best management practice

BOD biochemical oxygen demand

CBOD carbonaceous biochemical oxygen demand

CFR Code of Federal Regulations

COD chemical oxygen demand

CPI corrugated plate interceptor

CPVC chlorinated polyvinylchloride

CRREL Cold Regions Research and Engineering Laboratory (U.S.Army)

CSC chloride stress cracking

DAF dissolved air flotation

DC direct current

DoD Department of Defense

EPA U.S. Environmental Protection Agency

F/M food-to-microorganism ratio

FOTW federally owned treatment works

FRP fiberglass reinforced plastic

HI host installation

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MCRT mean cell residence time

mgd million gallons per day

MPN most probable number

MSDS material safety data sheets

NFPA National Fire Protection Association

NPDES National Pollutant Discharge Elimination System

O&M operations and maintenance

PE polyethylene

POTW publicly owned treatment works

PVC polyvinylchloride

RBC rotating biological contactor

RCRA Resource Conservation and Recovery Act

SCC stress corrosion cracking

SDWA Safe Drinking Water Act

SSPC Steel Structures Painting Council

TKN total kjeldahl nitrogen

TMDL total maximum daily load

TSS total suspended solids

WEF Water Environment Federation

WWTP wastewater treatment plant

UIC underground injection control

VSS volatile suspended solids

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CONCLUDING MATERIAL

CUSTODIANS: PREPARING ACTIVITY: AF-50 NAVY-YD2 NAVY-YD2 ARMY-CE

PROJECT NUMBER: FACR 1170

STANDARDIZATION DOCUMENT IMPROVEMENT PROPOSALINSTRUCTIONS

1. The preparing activity must complete blocks 1, 2, 3, and 8. In block 1, boththe document number and revision letter should be given.

2. The submitter of this form must complete blocks 4, 5, 6, and 7.

3. The preparing activity must provide a reply within 30 days from receipt of theform.

NOTE: This form may not be used to request copies of documents, nor to requestwaivers, or clarification of requirements on current contracts. Commentssubmitted on this form do not constitute or imply authorization to waive anyportion of the referenced document(s) or to amend contractual requirements.

I RECOMMEND A CHANGE:1. DOCUMENT NUMBER

MIL-HDBK-1138

2. DOCUMENT DATE (YYMMDD)

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3. DOCUMENT TITLE WASTEWATER TREATMENT SYSTEM OPERATIONS AND MAINTENANCE AUGMENTING HANDBOOK

4. NATURE OF CHANGE (identify paragraph number and include proposed rewrite, if possible. Attach extra sheets as needed.)

5. REASON FOR RECOMMENDATION

6. SUBMITTERa. NAME (Last, First, Middle Initial) b. ORGANIZATION

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7. DATE SUBMITTED:

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8. PREPARING ACTIVITYa. NAME b. TELEPHONE (Include Area Code)

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c. ADDRESS (Include Zip Code) IF YOU DO NOT RECEIVE A REPLY WITHIN 45DAYS, CONTACT:Defense Quality and StandardizationOffice5203 Leesburg Pike, Suite 1403, FallsChurch, VA 22041-3466Telephone (703) 756-2340 DSN 289-2340

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