wastewater treatment plant sludge and biosolids - suma · wastewater treatment plant sludge and ......

Commissioned by: Communities of Tomorrow Leveraged Municipal Innovation Fund

Prepared by: Enviseng Environmental Consulting Services November 5, 2012

Wastewater Treatment Plant Sludge and Biosolids

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Heavy Metals, Nutrients, Pathogens, Alum Recovery

BENEFICIAL PRACTICE AND APPROPRIATE TECHNOLOGY GUIDE

WASTEWATER TREATMENT PLANT SLUDGE AND BIOSOLIDS

VOLUME 1

HEAVY METALS, NUTRIENTS, PATHOGENS, ALUM RECOVERY

PREPARED FOR:

COMMUNITIES OF TOMORROW

PREPARED BY:

ENVISENG ENIVRONMENTAL CONSULTING SERVICES

5 November, 2012

“Bright Waters-Bright Fish”

E-E-C-S

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TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY………………………………………………………………………………………………………….. 1

1. INTRODUCTION………………………………………………………………………………………………………………. 3

Objectives, Scope, Rational

2. HEAVY METALS……………………………………………………………………………………………………………….. 3

Sludge and Biosolids Characterizations/Concerns

Regulations: Current & Future

What You Should Know About Your Sludge & Biosolids

Beneficial Practices and Choices

Public Acceptance

Summary

3. NUTRIENTS………………………………………………………………………………………………………………….… 7





Public Acceptance

Summary

4. PATHOGENS…………………………………………………………………………………………………….……………. 9





Public Acceptance

Summary

5. ALUM USE AND RECOVERY…………………………………………………………………………………………… 12



What You Need To Know About Your Sludge & Biosolids


Public Acceptance

Summary

6. STRATEGIC CONSIDERATIONS……………………………………………………………………………………….. 14

7. APPLICATION AND LIMITATIONS…………………………………………………………………………………… 15

8. USEFUL WEBSITES AND REFERENCES…………………………………………………………………………….. 15

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APPENDIX 1 - PLANT VISIT NOTES

APPENDIX 2 - TASK 1 REPORT-REVIEW OF STUDY ON NATIONAL RESEARCH AGENDA &

REVIEW OF DRAFT NATIONAL GUIDANCE DOCUMENT ON BENEFICIAL USE OF

MUNICIPAL BIOSOLIDS

APPENDIX 3 -TASK 2 REPORT-LITERATURE REVIEW

ACKNOWLEDGEMENTS

This project was undertaken with funding from the LMIF (Leveraged Municipal Innovation

Fund) co-ordinated and administered by Communities of Tomorrow.

Communities of Tomorrow Bland Brown, Project Lead, Technical Support & Business

Development Coordinator

Kevin Marpole, LMIF Coordinator, Business Development

Officer

Kimberly Exner, Chief Operating Officer

City Co-Sponsors Colin Innes, City Of Prince Albert

Peter Hagar, City Of Regina

City Participants Prince Albert, North Battleford, Yorkton, Swift Current,

Regina, Saskatoon and Moose Jaw

Advisory Committee Each City (one or more staff members)

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EXECUTIVE SUMMARY

In 2011 discussions between Communities of Tomorrow and the larger urban municipalities

identified a desire and need for development of a Beneficial Practice and Appropriate

Technology Guide addressing municipal wastewater treatment plant sludge and biosolids. The

objective was to develop a reference document with emphasis on beneficial practices based on

current knowledge, verified technology and established practice. The scope of the Guide was

defined through consultation with an advisory group with representation from Saskatchewan

cities that operate mechanical/biological wastewater treatment plants. It was decided to

pursue a phased approach to development of the Guide. The first phase was designed to focus

on the operational needs that relate to the chemical, biological and physical properties of

wastewater sludge and biosolids.

Heavy metals, nutrients, pathogens and alum recovery were selected for this component of the

Guide. Each aspect is addressed in terms of characteristics and concerns, current and future

regulations, what you should know about your sludge and biosolids, beneficial practices and

choices, and public acceptance. In addition guidance is offered in terms of the following

strategic considerations regarding selection, operation and management of sludge and

biosolids plans.

Set Objectives

Base the long-term management strategy on a commitment to adopt practices that will

make beneficial use of the wastewater sludge and biosolids.

Adopt a Holistic Approach

Make sludge and biosolids management an integral part of the overall wastewater

treatment strategy and plans for continuous improvement of operating practices.

Control and Manage Inputs

Develop, maintain and enforce a Sewer Use Bylaw to control the forms and amounts of

heavy metals, nutrients and solids that are permitted to be discharged to the municipal

sewer system. The bylaw should reflect contemporary regulations and support the overall

needs of the wastewater treatment strategy.

Monitor Constituents in Sludge and Biosolids

Test and monitor constituents of interest (i.e. heavy metals, nutrients, pathogens) on a

regular basis to provide information for effective management of sludge and biosolids.

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Manage Public Information, Concerns and Perceptions

Adopt operating standards and communication strategies that inform and respond to public

concerns about potential health, safety and aesthetic impacts of sludge and biosolids

management practices.

Sludge and biosolids applied research is ongoing, process technology is quite extensive and

moving to energy efficiency, and general trends are towards sustainable beneficial use of

biosolids wherever possible. Cost effective management of sludge and biosolids must reflect

regulatory requirements, process reliability and flexibility, liability, and public acceptance.

The next phase of this initiative is to develop a guidance document on beneficial practices and

appropriate technology for management of wastewater sludge and biosolids covering the

mechanical, chemical and biological processes involved in treatment, processing, reuse and

disposal of wastewater sludge and biosolids.

GLOSSARY OF ACRONYMS

Alum Aluminum Sulphate

BNR Biological Nutrient Removal wastewater treatment process

CCME Canadian Council of Ministers of Environment

Class A Class of treated biosolids allowing unrestricted use

Class B Class of treated biosolids allowing restricted use

CT Communities of Tomorrow

EBPR Enhanced Biological Phosphorous Removal wastewater treatment process

E-Coli Escherichia Coliform-a bacteria commonly found in the lower intestine of warm-

blooded animals used as an indicator monitoring organism

H1N1 Swine and avian influenza virus that causes contagious respiratory disease

Kg Kilogram-a weight measure

LMIF Leveraged Municipal Innovation Fund-administered and co-ordinated by CT

mg/kg milligrams per kilogram –weight per weight measure of concentration in a solid

mg/l milligrams per litre-weight per volume measure of concentration in a liquid

MPN Most Probable Number-an indicated count of organisms

MRSA Methicillin Resistant Staphylococcus Aureus - an antibiotic resistant staph

infection bacteria

N Nitrogen

NOx Nitrogen Oxide

P Phosphorous

P2O5 Phosphorous Oxide

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1. INTRODUCTION

In 2011 discussions between Communities of Tomorrow and the larger urban municipalities

identified a desire and need for development of a Beneficial Practice and Appropriate

Technology Guide addressing municipal wastewater treatment plant sludge and biosolids. The

project involved undertaking a review of federal /provincial initiatives at the CCME level as well

as a literature review.

Objectives/Scope/Rational

The objective was to develop a reference document with emphasis on beneficial practices

based on current knowledge, verified technology and established practice. The guide focus was

to be on operational needs that relate to the chemical, physical and biological properties of

sludge and biosolids. Heavy metals, nutrients, pathogens and alum recovery were selected for

this component of the guide. The Guide outlines options and beneficial practices,

implementation strategies for selecting and applying appropriate established practice, current

knowledge and technology of interest to participating municipalities with respect to the

selected aspects of municipal sludge and biosolids.

2. HEAVY METALS


Municipal wastewater sludge and biosolids are known to contain heavy metals that can be of

concern to the environment and human health. The source of the heavy metals ranges from

commercial and industrial wastewater discharges, to leaching of sewage system piping and

plumbing fixtures as well as domestic wastewater constituents. Municipal wastewater sludge

solids are known to adsorb heavy metals contained in the raw municipal wastewater. In a

Canadian study the heavy metal removal from the wastewater into the sludge solids (and

biosolids) ranged from a low average of 44% to a high average of 62%.

The level of heavy metals in municipal sludge and biosolids based on recent characterization at

11 wastewater plants in Canada and at 6 plants in Saskatchewan is shown as follows:

Heavy Metal Levels In Biosolids (mg/kg dry weight basis)

Canada Saskatchewan Canada Saskatchewan

Arsenic 2.6 7.7 Mercury 0.68 1.02

Cadmium 1.1 1.8 Molybdenum 3.5 12.2

Chromium 20.3 37.7 Nickel 10.5 35.7

Cobalt 2.9 5.5 Selenium 2.15 8.7

Copper 271 565 Zinc 331 632

Lead 24 38.8

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This comparison indicates heavy metal levels in Saskatchewan city sludge and biosolids are

generally higher than the Canadian city average. It is likely the country wide data is reflective of

more stringent sewer use bylaw heavy metal limits in the larger Canadian cities.

Heavy metals do accumulate in soils and safe levels have been established and are included in

provincial and federal regulatory guidelines. Studies in the US have documented that metal

uptake by plants and crops in soils where sludge and biosolids have been applied are generally

minimal averaging 0.8 % of the combined soil/ biosolids heavy metal content. Canadian

research indicated the heavy metal uptake in biosolids amended soils was lower than from non-

biosolids amended soils. Research in the US has determined that when biosolids are applied to

land, at compliant regulatory guideline rates, no toxic responses to microbial respiration,

earthworm biomass, or seed germination was evident. Biosolids aging was also found not to

increase heavy metal bio-accessibility.


In Saskatchewan the heavy metal in sludge and biosolids limits are comparable with those in

other provinces. The current Saskatchewan limits are as follows:

Saskatchewan Heavy Metal Limits in Biosolids (mg/kg dry weight)

Arsenic 75 Mercury 5

Cadmium 20 Molybdenum 20

Chromium 1060 Nickel 180

Cobalt 150 Selenium 14

Copper 760 Zinc 1850

Lead 500

Saskatchewan criteria for maximum heavy metal levels in agricultural soils are as follows:

Saskatchewan Heavy Metal Maximum in Agricultural Soils (mg/kg dry weight)

Arsenic 12 Mercury 6.6

Cadmium 1.4 Molybdenum 5

Chromium 64 Nickel 50

Cobalt 40 Selenium 1

Copper 63 Zinc 200

Lead 70

These levels must be utilized in determining sludge and biosolids loadings whenever the

beneficial practice of applying biosolids to agricultural land is planned. The natural soil level

must be monitored for these heavy metals and added to those projected to be applied in the

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biosolids to ensure the combined limit for each heavy metal in the agricultural soil is not

exceeded.

While Saskatchewan does not have regulatory levels for heavy metals in finished biosolids

compost, criteria exist as issued by Canadian Council of Ministers of the Environment (CCME).

Conversion of sludge and biosolids into a compost end product material is a fairly common

beneficial use practice in Canada. Class A criteria for unrestricted compost use and Class B

criteria for restricted compost use are as follows:

CCME Compost Heavy Metal Criteria (mg/kg dry weight)

Class A Class B Class A Class B

Arsenic 13 75 Mercury 0.8 5

Cadmium 3 20 Molybdenum 5 20

Chromium 210 NR Nickel 62 180

Cobalt 34 150 Selenium 2 14

Copper 400 NR Zinc 700 1850

Lead 150 500


Regular testing and monitoring of the heavy metal concentrations (mg/kg dry weight basis) in

sludge and biosolids is essential to knowing whether heavy metals will be a concern.

Information can be compared to regulatory guidelines which vary depending upon the end use

of the biosolids. In Saskatchewan the concentration of eleven heavy metals must be

determined in the wastewater treatment plant residual solids. In some cases this will be

digested dewatered biosolids, where in other cases it will be finished compost. In this project 7

Saskatchewan cities were visited. Three cities produce compost as the final biosolids product

for use in the landfill final cover soil mix to support vegetation cover. One city produces an

anaerobically digested biosolids for local agricultural land application. One city disposes of

dewatered undigested waste activated sludge to the municipal landfill as a solid waste. Two

cities send their waste activated sludge to lagoon cell storage with the ultimate use/disposal of

the biosolids undetermined at this time.

Based on data available and or provided to this study, 3 out of 6 Saskatchewan cities had some

heavy metal concentrations (one or two elements) that exceed current Saskatchewan

Environment guidelines for agricultural land application. With respect to criteria for heavy

metals in compost, 6 Saskatchewan cities show some heavy metals in their final biosolids

material (one to five elements) that exceed the current CCME Compost Class A level for heavy

metals. Three cities show some heavy metals in their final biosolids material (one or two

elements) that exceed CCME Compost Class B level.

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A review of the literature indicates there are essentially no practical economic processes for

removal of heavy metals from wastewater sludge and biosolids. It is therefore imperative to

control heavy metals in the raw sewage since upwards of 60% of the heavy metals within the

raw wastewater end up in the wastewater plant sludge and biosolids. This has been recognized

across the country resulting in development of sewer use bylaws that regulate heavy metal

disposal to municipal wastewater systems. Most recently CCME (2009) produced a model

sewer use bylaw wherein heavy metal limit criteria were selected for those eleven heavy metals

that are regulated in sludge and biosolids in Saskatchewan and Canada. Where heavy metals in

a wastewater sludge or biosolids are in excess of regulatory guidelines and limits , the city can

choose to incorporate more stringent heavy metal limits into its sewer use bylaw and take

enforcement actions to ensure commercial and industrial dischargers adhere to the

requirements. Canadian experience shows that with the adoption of more stringent heavy

metal limit in municipal sewer use bylaws the levels of heavy metals in the wastewater sludge

and biosolids has dropped quite dramatically averaging +70% reduction.

CCME Model sewer use bylaw recommended criteria for heavy metals (mg/L)

Arsenic 1.0 Mercury 0.01

Cadmium 0.7 Molybdenum 5.0

Chromium 2.8 Nickel 2.0

Cobalt 5.0 Selenium 0.82

Copper 2.0 Zinc 2.0

Lead 0.7

Public Acceptance

Generally heavy metals in sludge and biosolids are not a significant public concern where the

sludge or biosolids material and end use comply with current regulatory requirements (content

and application rates). Heavy metal limits have been established for biosolids agricultural land

application and biosolids containing compost products that are based on extensive research in

recent years on heavy metal uptake in plants and on detailed health and environmental risk

assessment analysis. Compliance with approved regulatory guidelines and standards allows for

the beneficial use of biosolids safely.

Summary

Municipal sludge and biosolids adsorb a large portion of heavy metals within raw wastewater.

Heavy metals are highly regulated in Saskatchewan and Canada in biosolids, compost and soils.

Control of heavy metals using appropriate Sewer Use Bylaws properly enforced has proved to

control and substantially reduce concentrations in final biosolids materials and end use

products. Heavy metal uptake by plants and crops where biosolids end products have been

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applied in accordance with regulations has been found to be very low and effects on soil

biology have been found to be non-toxic.

3. NUTRIENTS


Municipal sludge and biosolids contain nutrients nitrogen and phosphorous in considerable

quantities that are valuable for agriculture, forestry, landscaping, and reclamation uses. The

level of each nutrient in biosolids is in part dependent upon input sources as well as upon the

type of wastewater and sludge treatment and processing in the respective municipality.

Nitrogen and phosphorous levels in the biosolids of eleven (11) Canadian cities, based on

recent CCME data, ranged from 1.2 to 11.6 % nitrogen (averaging 4.1%) and 0.3 to 3.8 %

phosphorous ( average 1.7%). Data for this CT study from six (6) Saskatchewan cities show an

average of 3.2% nitrogen and 1.9% phosphorous, which is quite close to the broader national

average.

The two main nutrients are generally considered to be a beneficial characteristic of biosolids

where biosolids are utilized according to regulatory guidelines for rate application as soil

amendment for plant growth. Nitrogen can be an issue where biosolids are incinerated as it

can contribute to NOX (nitrogen oxide) emissions.


Most Canadian provinces have regulatory rules/guidelines for biosolids beneficial use however

none have any specified upper levels for Nitrogen or Phosphorous in biosolids. Regulatory

control is specified in terms that land application is to be based on agronomic application rates

consistent with the crop to be planted on the land. In Saskatchewan current land application

guidelines require nitrogen “application rates not to exceed the agronomic rate (a rate

equivalent to the amount of fertilizer nitrogen applied to the soil for the crop grown”).

Saskatchewan sludge to land application guidelines do not currently regulate phosphorous in

biosolids.

Many US states now regulate phosphorous application rate as well as nitrogen since it has

been shown that long term accumulation of P in the soil can exceed concentrations needed for

optimum plant yields resulting in phosphorous migration to ground and surface waters with

detrimental consequences. As a result many US states are now requiring agronomic application

rates to include both nitrogen and phosphorous calculations in determining which will govern

the ultimate biosolids application rate for a particular field. Ontario also requires this

calculation and Manitoba is also considering requiring phosphorous agronomic rates.

Application rates to agricultural land based on phosphorous result in a much lower tonnage per

hectare than would be the case based on nitrogen.

Saskatchewan Ministry of Environment have indicated an update of the current Land

Application of Sewage Sludge Guidelines is planned. It is possible that future agronomic

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application determination in Saskatchewan may include the need to assess both nitrogen and

phosphorous in establishing the governing biosolids field application rate.


Regular testing and monitoring of wastewater plant final sludge or biosolids should be

undertaken for both nitrogen and phosphorous (mg/kg dry weight basis). This data is useful to

plan ultimate biosolids beneficial use strategies, for discussion with local agricultural

landowners who may be prospective users, and to determine field application rates that

conform to regulatory requirements (agronomic rates). Nutrient content of a wastewater plant

final sludge or biosolids will change if further treatment (lagoon storage), or amendments are

added for example in composting (wood shavings, yard waste, livestock show or manure

wastes). In these cases it will be necessary to test and monitor the “final” biosolids containing

product for nitrogen and phosphorous where land application is contemplated.

Although biosolids are applied at an agronomic rate, it is important to know that nitrogen

mineralization occurs quite slowly with only 20 to 30 percent of the organic nitrogen content of

biosolids becoming available to plant growth in year one after application. Aging of biosolids

(surface or lagoon storage, or composting) results in some loss of nitrogen by ongoing

mineralization to ammonia and loss to atmosphere.

Typically a crop like wheat in the Prairie Provinces requires between 0.8 and 1.1 kg of nitrogen

per bushel of crop production. With a projected crop of 100 bushels per hectare, the target

nitrogen loading would be around 100 kg per hectare. It is necessary to test each field soil to

establish the existing soil nitrogen content to calculate the ultimate biosolids application rate

that will meet the target agronomic rate as per regulatory requirements.

The type of wastewater treatment system also has an impact on nutrient level of the sludge or

biosolids. Biological Nutrient Removal (BNR) wastewater treatment plants that are designed for

nitrogen control remove considerably more of the incoming nitrogen in the raw wastewater

however can result in higher biosolids nitrogen (N) content than a conventional activated

sludge plant. Other BNR wastewater plants are designed for phosphorous (P) reduction and can

result in higher phosphorous content of biosolids. Some EBPR (enhanced biological

phosphorous removal) plants that focus on P reduction are now incorporating side-stream P

removal processes (example Ostara process) that removes a large portion of the P from the

sludge or biosolids circuit. These side stream P removal processes are usually installed to

reduce Struvite (a crystallized phosphorous compound) that can clog pipes and adhere to

pumps and in-vessel equipment problems. Nutrient removal processes such as BNR and EBPR

can have some impact on desirability of the ultimate biosolids beneficial use for plant growth

since these nutrients are very valuable to the farmer as they reduce the need to purchase

equivalent amounts of costly chemical fertilizers.


In order to make best beneficial use of the ultimate wastewater treatment plant biosolids, it is

important that the treatment processes utilized recognize and support the biosolids

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management plan options. The nutrients nitrogen and phosphorous are valuable in that the

biosolids content of these can be utilized to offset costly chemical fertilizers used by farmers,

landscapers, and land reclamation projects. A recent CCME Guidance Document for Beneficial

Use of Municipal Biosolids strongly supports the beneficial use of the inherent value of

nutrients in biosolids. Each municipality can choose to select a biosolids management scheme

most suitable to their area, as opposed to landfilling or incineration which are not considered

beneficial uses by most provincial regulatory agencies (and CCME). In addition each municipal

wastewater plant can choose to include nitrogen and phosphorus limits in its sewer use bylaw

to be met by commercial and industrial dischargers since treatment for reduction of these

parameters adds considerable cost to wastewater treatment. CCME recommends in its model

sewer use bylaw that nitrogen (N) limits be 50 mg/l and phosphorous (P) be limited to 10 mg/l.

Commercial and industrial wastewaters in excess of these values should be restricted or

required to pay a treatment surcharge.

Public Acceptance

Public acceptance of biosolids beneficial uses is very favourable with respect to the aspect of

nutrient (N & P) recycling for plant growth use in agriculture land application, compost

products, landscape material products, forestry and land reclamation provided regulatory

standards and guidelines are followed in the biosolids management scheme.

Summary

Biosolids contain valuable nutrient nitrogen and phosphorous. Land application is one of the

major beneficial uses of treated biosolids however close management is necessary to ensure

agronomic design is utilized in planning to avoid environmental problems, to meet regulatory

requirements and to maximize utilization of the biosolids resource. Nitrogen and phosphorous

removal processes for wastewater treatment are becoming more common in order for an

urban municipality to meet regulatory agency discharge requirements. These processes can

have an impact on the wastewater plants final biosolids nutrient content and thus the N and P

content of treated biosolids applied to beneficial uses such as agricultural land application,

compost products, forestry and land reclamation. It is important to follow application

guidelines in order to avoid nutrient runoff and migration to surface and subsurface water

systems.

4. PATHOGENS


Municipal wastewater sludge and biosolids are known to contain various disease causing

pathogens including bacteria, viruses, and parasites. The pathogen content of sludge and

biosolids is dependent on the process used in wastewater treatment but mainly on the level to

which the residual sludge and biosolids are treated. Pathogen content is therefore a very

important factor in a biosolids management scheme and ultimate disposal or beneficial use

plan adopted.

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In Canada organisms have been identified by regulatory agencies for monitoring to represent

and regulate the pathogen levels in sludge and biosolids. These organisms include fecal

indicator bacteria, either Fecal Coliform or E Coli, and Salmonella bacteria which is a pathogen.

In untreated municipal sludge the level of fecal coliforms is typically up to 10 million MPN (most

probable number) per gram of dry solids, whereas sludge Salmonella bacteria are typically up to

100 MPN per gram dry solids. Other pathogens have been detected and studied in the past

decade, such as Listeria bacteria, Giardia and Cryptosporidium (protozoan parasites), H1N1

(avian influenza virus), and MSRA (antibiotic resistant staph infection bacteria) however there

are currently no requirements to monitor these in sludge and biosolids management schemes

in Canada.

As part of this CT project information on pathogens in sludge and biosolids was provided where

available by seven (7) participating cities in Saskatchewan. At three (3) cities where wastewater

sludge produced that is not treated and is not currently beneficially utilized (lagooned or

landfilled), pathogen levels in the final untreated sludge are not currently monitored. At four

(4) cities where wastewater sludge is treated and the biosolids are beneficially utilized

(agricultural land applied or used in landfill final cover soil mix), some pathogen levels are

regularly monitored. Two of these cities monitor fecal coliform and salmonella bacteria levels,

one city monitors only fecal coliform bacteria levels and one city provided no information at the

time of this guide preparation.


Pathogen levels are regulated in most provinces and to some degree at the federal government

level. CCME has both indicator and pathogen bacteria standards for finished compost made

from or with municipal wastewater biosolids. Fecal Coliform is to be less than 1000 MPN/gram

dry solids, or have “no” Salmonella bacteria in a test with detection less than 3 MPN/4 grams

dry solids. Furthermore the compost must have been processed to maintain a temperature of

55 degrees C or more for 3 days for any in-vessel or aerated static pile processes, or for 15 days

in any windrow process and also have received a minimum of 5 turnings.

Provincial guidelines and regulations for pathogen content in municipal sludge and biosolids for

beneficial use vary across the country. Many provinces have adopted a 2 Class system wherein

the biological standards to be met for unrestricted beneficial use of biosolids are much more

stringent than for restricted use. In Saskatchewan the current Sewage Sludge Guidelines for

Land Application requires sludge/biosolids to have Fecal Coliform bacteria level of 1000

MPN/gram dry solids or less “or” to have a Salmonella bacteria level not more than 3 MPN/4

gram dry solids. This current Saskatchewan guideline is essentially equivalent to other

provincial Class A non- restrictive use criteria. Five other Canadian provinces also have a Class B

standard for restrictive use of treated biosolids which requires only the Fecal Coliform bacteria

level to be not more than 2,000,000 MPN/gram dry solids. In the future it is likely that

Saskatchewan guidelines will be modified to include a Class 2 standard as well based on

communication with the Ministry of Environment.

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It is important to know pathogen levels in your wastewater plant final sludge or biosolids thus

regular periodic testing and monitoring of Fecal Coliform and Salmonella bacteria levels should

be undertaken. This data is valuable to compare to regulatory requirements for beneficial use

of biosolids, to allow planning and selection of sludge treatment processes, and to confirm the

performance of the biosolids management plan selected. These data are necessary to

determine whether regulatory guidelines and standards for your particular biosolids beneficial

use strategy are being met.


There are numerous types of processes utilized for biosolids treatment to attain pathogen

reduction (as well as stabilization of the sludge/biosolids organic fraction). Anaerobic digestion

is a common process for sludge treatment. Mesophilic anaerobic digestion operates at around

35 degrees C and can produce a pathogen reduction able to meet Class B (less than 2,000,000

Fecal Coliform per gram dry solids). Three cities in Saskatchewan use mesophilic anaerobic

digestion as part of their sludge treatment strategy. Thermophilic anaerobic digestion

operates at around 55 degrees C and can produce a pathogen reduction to meet a Class A level

(less than 1000 Fecal Coliform MPN per gram dry solids, and Salmonella bacteria less than 3

MPN per 4 grams dry solids).

Composting is also a very common process for municipal wastewater sludge treatment in

Canada and other countries. In many cases composting is undertaken in addition to

conventional sludge digestion (aerobic or anaerobic) to provide further pathogen reduction and

to make use of the nitrogen content of treated sludge to help compost other municipal sourced

solid wastes (i.e. yard waste, industrial organics, stockyard wastes). Composting in combination

with mesophilic anaerobic digested sludge can produce a pathogen reduction to meet Class A

level. Composting of untreated dewatered wastewater sludge can also usually produce a

pathogen reduction to meet Class A using in-vessel or aerated static pile composting processes.

Two Saskatchewan cities currently use composting after mesophilic anaerobic sludge

treatment, and one currently uses an in-vessel composting of undigested dewatered

wastewater sludge.

Sludge storage over time will provide some pathogen reduction. Two Saskatchewan cities use a

treated biosolids lagoon storage element after mesophilic anaerobic sludge treatment which

enhances further pathogen reduction (however this reduction is currently un-quantified). Two

Saskatchewan cities currently use lagoon storage of undigested wastewater sludge. Research

seems warranted to determine whether the in-lagoon sludge storage anaerobic activity over

time could produce a cost effective lagoon biosolids treatment that meets at least a Class B

pathogen reduction level suitable for restricted agricultural land application without upstream

digestion in the Canadian prairie climate.

Other biosolids treatment processes are utilized for excellent pathogen reduction to meet Class

A level in larger cities. These include alkaline treatment, heat drying, and incineration. In most

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of these cases sludge is digested before these secondary treatments to provide a stabilized

sludge feed in order to prevent odour emissions that can be associated with these processes

when they are used on un-stabilized/ un-digested dewatered sludge.

It should be noted that incineration of biosolids is not considered by CCME to be a beneficial

use of this resource unless it includes both energy capture/utilization and net greenhouse gas

reduction benefits. Landfill bury of sludge or biosolids is also not considered to be a beneficial

use of the resource. Thus schemes proposed using straight incineration or landfill bury will most

likely not get regulatory approval going forward. Biosolids used in a beneficial use scheme will

also be contributing to the sustainability factor in wastewater treatment.

Public Acceptance

Public acceptance of current biosolids management schemes is generally supportive of the

beneficial use and recycling of biosolids resources provided regulatory requirements for

pathogen reduction and associated health risk reduction, along with any associated restrictions

where warranted (setback distances, monitoring and reporting) are met consistently, and

where the public is kept informed and involved in planning and during operation of the

biosolids management scheme. Biosolids odour issues are the most common actual and

perceived public concern which biosolids management plans must also address by meeting

regulatory requirements for sludge and biosolids stability standards and guidelines.

Summary

Biosolids are highly regulated in Canada, mostly by Provincial jurisdictions. While currently

Saskatchewan has only one Class of sludge/biosolids pathogen criteria (essentially Class A),

many other Canadian provinces (and in the USA) have one level (Class A) of pathogen reduction

requirement for unrestricted beneficial use and a second lower level for pathogen reduction

(Class B) for restricted use. There are many municipal sludge and biosolids treatment options

available ranging from biological treatments to chemical treatments and heat treatments. The

choice depends upon the end use planned for the biosolids as well as case specific factors

including whether land application options are available, and capital and operation costs. The

trend globally and in North America is to treat municipal sludge to produce at least Class B

biosolids where land application (i.e. agricultural, forestry/silviculture, land reclamation or

landfill cover mix use) is an option and good planning and management are developed and

implemented. In higher populated areas the trend is to produce Class A biosolids which allows

many other beneficial use options and generally also less public opposition and concern.

5. ALUM USE AND RECOVERY


Alum is a common chemical used in water and wastewater treatment. In water treatment it is

used as a coagulant for removal of suspended solids and turbidity. In wastewater treatment it

has found use as a chemical to react with phosphorous for P nutrient reduction in tertiary

treatment processes. Two cities is Saskatchewan currently use alum for phosphorous reduction

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purposes. One city uses alum in a tertiary treatment process for reduction of phosphorous in

secondary aeration lagoon effluent and has done so for over 40 years. Another city adds alum

to the secondary clarifier influent, at a new high rate BNR secondary treatment system, for

phosphorous reduction. Alum added in water treatment ties up inorganic sediments in the raw

water however it can also help remove algae in the surface water source. Alum in tertiary

wastewater treatment use ties up phosphorous and biological treatment suspended solids in

the treated wastewater. In this case the alum sludge produced will have elevated levels of

phosphorous as well as considerable biomass type organics. In addition in this case alum sludge

can also contain considerable algae solids in the summer when used for tertiary treatment of

aeration lagoon effluents.

Alum sludge is very gelatinous and has been found difficult to dewater. Thus in many cases the

alum treatment process underflow may be transferred to alum sludge storage lagoons. With

respect to alum sludge effects on plant growth an assessment in Quebec found alum containing

biosolids did not limit plant growth or yield. US investigations however found water treatment

plant alum sludge did affect yield of grass and attributed the impact to the alum sludge

reducing soil available phosphorous at higher loadings.


Alum sludge is regulated in some jurisdictions since water plant alum does tie up the

phosphorous and affect its bioavailability in agricultural land applications. Also due to high

level of phosphorous in alum sludge from wastewater plant use there is a risk of phosphorous

migration to surface and groundwater in acidic soils. Saskatchewan does not currently make

reference to any specific requirements for alum type sludge in its current guidelines for land

application of municipal sludge. Ontario and Quebec do regulate alum sludge application to

land and require the soil to be tested for available phosphorous (P). The intent is to restrict

phosphorous level in the land to a maximum level of 60 mg/kg of P2O5 above which no alum

biosolids can be added. This level is generally related to agronomic crop needs. In Ontario the

assumption is 40% of P in the soil is available for plant use in year 1, another 40% in the

following years, and that 20% of the phosphorous will never be available for plant use.


As with any sludge or biosolids, in order to support application to regulatory authorities for

ultimate disposal or beneficial use, it is important to know the material analyses. For alum type

sludge, aluminum content, total and available phosphorous, as well as heavy metals,

pathogens, volatile solids , and nitrogen content should be tested and monitored to provide

basic information. Likewise if alum (and possibly phosphorous) recovery is of interest these

data (and perhaps other parameters) would be valuable for such considerations.


Alum sludge from water treatment plants has been found to be of value for reuse in

wastewater treatment since it has residual phosphorous removal characteristics, where

transportation economics are favourable. Alum recovery from alum sludge has been applied at

14

both water and wastewater treatment plants, although there are not a large number of

systems operating. Most alum recovery processes found in the literature are based on a

sulphuric acid reactor process. Alum recovery ranges from 80 to 90 % and is described as

effective as the original alum chemical. Other new recovery processes are identified in the

literature as well including an alkaline based process and a cation exchange membrane based

process. The literature reviewed does not describe the economics in much detail and this

would be a very important factor in considering alum recovery. One factor that may affect the

economics might be recovery of phosphorous in addition to the alum. Phosphorous recovery

from wastewater sludge has recently seen advances. Several wastewater plants have now

incorporated P recovery economically (i.e. Ostara process) however primarily to control Struvite

problems. No references were found in the literature where both alum and P are being

recovered from alum sludge.

6. STRATEGIC CONSIDERATIONS

The selection, operation and management of a sludge and biosolids plan include the following

strategic considerations:

Set Objectives

Base the long-term management strategy on a commitment to adopt practices that will make

beneficial use of the wastewater sludge and biosolids.

Adopt A Holistic Approach

Make sludge and biosolids management an integral part of the overall wastewater treatment

strategy and plans for continuous improvement of operating practices.

Control and Manage Inputs

Develop, maintain and enforce a Sewer Use Bylaw to control the forms and amounts of heavy

metals, nutrients and solids that are permitted to be discharged to the municipal sewer system.

The bylaw should reflect contemporary regulations and support the overall needs of the

wastewater treatment strategy.

Monitor Constituents in Sludge and Biosolids

Test and monitor constituents of interest (i.e. heavy metals, nutrients, pathogens) on a regular

basis to provide information for effective management of sludge and biosolids.

Manage Public Information, Concerns and Perceptions

Adopt operating standards and communication strategies that inform and respond to public

concerns about potential health, safety and aesthetic impacts of sludge and biosolids

management practices.

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7. APPLICATION AND LIMITATION

The information presented in this document is intended to be an introductory resource

Beneficial Practice and Appropriate Technology Guide for Saskatchewan Cities (and other

smaller urban centres) who have sludge and biosolids to deal with in providing effective

municipal wastewater treatment systems in their community. The focus of this Guide is on

municipal sludge and biosolids heavy metals, nutrients, pathogens and in addition a brief

coverage of alum recovery. It is not intended to provide exhaustive coverage of these areas

however considerable literature was reviewed (Appendix 3) that has been published by

respected organizations as well as regulatory and scientific sources that cover municipal

wastewater treatment sludge and biosolids. Users should continue to consult with known

expertise from municipal engineering firms and regulatory agency resources accordingly for

detailed guidance to select, modify, optimize, design and effectively operate their sludge and

biosolids management systems. Selection factors must include: Cost, Regulatory Requirements,

Reliability, Liability, Flexibility, and Public Acceptance. The scheme selected must be

Sustainable, Cost Effective and provide Environmental and Public Health Protection.

Emphasis going forward is going to be on the beneficial use of wastewater treatment sludge

and biosolids in an environmentally safe and low health risk manner. This is the expectation of

Canadian and Provincial Regulatory Agencies, and is also the consensus position of municipal

managers and politicians, as well as both urban and rural residents, and biosolids end product

users.

8. USEFUL WEBSITES AND REFERENCES

Canadian Council of Ministries of the Environment

www.ccme.ca/publications

� Guidance Document for the Beneficial Use of Municipal Biosolids, Sludge and Treated

Septage (Not Yet Available -To Be Published by CCME in late 2012)

� Guidelines For Compost Quality 2005 PN 1340

� Canadian Legislative Framework For Wastewater Biosolids PN 1146

� Model Sewer Use Bylaw 2009 PN 1421

� Biosolids Emissions Assessment Model PN 1430, PN 1432

� Emerging Substances of Concern In Biosolids PN 1440, PN 1448

Saskatchewan Ministry of the Environment

www.environment.gov.sk.ca

� Land Application of Municipal Sewage Sludge Guidelines EPB 296, 2004

Canada Water Network

www.cwn-rce.ca

� organization that will coordinate Canadian biosolids research going forward from 2012

� National Research Agenda for Municipal Wastewater and Biosolids , Environment Canada,

March, 2012

16

US Environmental Protection Agency

www.water.epa.gov

� Biosolids Technology Fact Sheet-Land Application of Biosolids EPA 832-F-00-064, 2000

� Biosolids Technology Fact Sheet-Multistage Anaerobic Digestion EPA 832-F-06-031 , 2006

� Biosolids Technology Fact Sheet-Alkaline Stabilization of Biosolids EPA 832-F-00-052, 2000

� Biosolids Technology Fact Sheet-Odour Control In Biosolids Mgmt EPA 832-F-00-067, 2002

� Biosolids Technology Fact Sheet-Use of Composting For Biosolids EPA 832-F-02-024, 2002

� Biosolids Technology Fact Sheet-In-Vessel Composting of Biosolids EPA 832-F-00-061, 2000

� Biosolids Technology Fact Sheet-Use of Landfilling For Biosolids EPA 832-F-03-012

� Biosolids Technology Fact Sheet-Heat Drying EPA 832-F—06-029, 2006

� Targeted National Sewage Sludge Survey Statistical Analysis Report EPA 822-R-08-018, 2009

� EPA Part 503 Biosolids Regulations

www.epa.gov/nrmrl/publications.html

� US EPA research publications on sludge and biosolids

InfraGuide

www.infraguide.ca

� Storm & Wastewater –Innovation & Best Practice: Biosolids Management Programs, 2003

Water Environment Federation

www.wef.org/biosolids

� National Biosolids Partnership –Manual of Good Practice For Biosolids, 2005

� Charting The Future of Biosolids Management , 2011

Water Environment Research Foundation

www.werf.org

� Multiple Reports on Biosolids research studies

Canadian Water And Wastewater Association

www.cwwa.ca/cbp-pcb/home/home_e.asp

� Canadian National Biosolids Partnership

Water Environment Association of Ontario

www.weao.org/residuals_and_biosolids

� Fate & Significance of Selected Contaminants in Sewage Biosolids Applied to Agric Land

� Other Biosolids reports and documents of the Water Environment Association of Ontario

� “Biosolids Naturally Sustainable” Video, 2012

Canadian Food Inspection Agency

www.inspection.gc.ca/plants/fertilizers/trade-memoranda

� Regulation of Compost Under The Fertilizer Act & Regulations T-4-120, 2009

17

National Academy Press

www.nap.edu

� National Research Council Biosolids Applied To Land Advancing Standards & Practices, 2002

International Water Association

www.iwapublishing.com

� Wastewater Sludge A Global Overview Of The Current Status & Future Prospects, 2011

Northwest Biosolids Management Association (Northwest USA)

www.nwbiosolids.org/index.php

� On line library list of biosolids studies and reports of this organization

Ostara

www.ostara.com

� Canadian company Ostara biosolids phosphorous recovery process

Nextera

www.nextera.ca/files/gasification-technology.php

� Canadian company Nextera- biosolids gasification process

SciVerse

www.sciencedirect.com/

� publisher of biosolids books and publications

IngentaConnect

www.ingentaconnect.com/content/wef/wefproc

� publisher of annual WEFTEC Conference Proceedings which includes Residuals and Biosolids

presentations, and specialty WEF Residuals And Biosolids Conferences

American Society For Microbiology

www.asm.org

� Report : Land Application Of Organic Residuals-Public Health Threat Or Environmental

Benefit (July 2011)

Western Canada Water and Wastewater Association

www.wcw.ca

� Annual Western Canada Water Conference proceedings available thru this site

Environment Canada

www.ec.gc.ca

National Research Agenda For Municipal Wastewater And Biosolids, March 2012

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