wastewater treatment - thunder bay

Annual Report 2020

WASTEWATER TREATMENT

Wastewater Treatment | ANNUAL REPORT 2020 1

Table of ContentsIntroduction ........................................................................................................3

Wastewater Treatment Process ........................................................................4

Wastewater Treatment Process Summary ........................................................6

Biosolids Summary........................................................................................... .8

Plant Treatment Process Schematic................................................................ .9

Infrastructure Projects................................................................................... .10

Wastewater System Summary............................................................... ..........12

Compliance & Quality Control Laboratory .................................................... .13

Calibration & Maintenance of Monitoring Equipment ....................................13

Sewer Use Control Program......................................................................... ...13

Complaints...................................................................................................... .14

By-Pass Events ................................................................................................14

Data Tables.......................................................................................................15

Staff Organization........................................................................................... .17

List of Figures

Figure 1: Monthly Effluent Results - TSS and CBOD5 .......................................6

Figure 2: Monthly Effluent Results - Total Phosphorus ....................................7

Figure 3: Monthly Effluent Results - pH ............................................................7

Figure 4: Monthly Effluent Results - Ammonia Nitrogen .................................8

Figure 5: Biosolids Shipped to Solid Waste & Recycling Facility ......................8

List of Data Tables

Table 1: Flows Received ...................................................................................15

Table 2: Plant Effluent Quality – Monthly Average Concentration ..................15

Table 3: Plant Effluent Quality – Monthly Average Loading ............................16

Table 4: Sludge Dewatering Results ...............................................................16

2 Wastewater Treatment | ANNUAL REPORT 2020


Introduction

The City of Thunder Bay (City) owns and operates the Water Pollution Control Plant (WPCP) located at 901 Atlantic Avenue. The Plant provides primary and secondary treatment, phosphorus and ammonia removal and anaerobic sludge digestion for the entire serviced area of Thunder Bay. Disinfection of the effluent occurs on a seasonal basis, from April 15 to October 15. The treatment facility has a rated capacity of 84.5 million litres per day.

This report is prepared on an annual basis to meet the requirements of the Ontario Ministry of the Environment, Conservation and Parks (MECP) amended Environmental Compliance Approval (ECA) #6927-9QDM2P for the design and operation of the Atlantic Avenue WPCP. It also serves to explain the operation of a vital part of the City of Thunder Bay’s infrastructure.


Wastewater Treatment Process

1. INFLUENT PUMP STATION

Wastewater from the serviced area in Thunder Bay enters the Water Pollution Control Plant at the Influent Pump Station (IPS) where five pumps are available to deliver the wastewater to the preliminary treatment process. The wastewater then flows by gravity to the end of the primary treatment process.

2. PRELIMINARY TREATMENT

The Preliminary Treatment Process removes large objects such as rags, paper, and wood debris. The wastewater enters two aerated grit tanks, where the flow is slowed to allow solids to settle out. Suspended, heavier material such as sand and gravel settles to the bottom of the grit tanks, where it is collected and dewatered by grit classifiers. This material is collected and hauled to the City’s Solid Waste and Recycling Facility (SWRF). Polymer is added to the grit tanks to increase the settlement of suspended solids. Aluminum sulphate is also added to help remove phosphorus and suspended solids.

3. PRIMARY TREATMENT

The Primary Treatment Process settles the organic material and dissolved contaminants by gravity in four large rectangular settling tanks (clarifiers). The wastewater flows very slowly through the clarifiers, where the wastewater, now called primary effluent, overflows the outlet weirs. A surface skimmer pushes fats, oils and greases (FOG), to the scum troughs, which then feed the FOG into the scum treatment system. Settled sludge is moved by a skimmer along the bottom to a sludge hopper where the sludge is collected and then treated in the anaerobic digesters to allow decomposition by micro-organisms.

4. SECONDARY TREATMENT

Secondary Treatment is a biological process that uses aerobic bacteria to consume suspended solids and dissolved organic materials in wastewater. The WPCP uses the Biological Aerated Filter (BAF) process. The BAF process removes biochemical oxygen demand, suspended solids and ammonia. In the filters, the primary effluent flows upward through a bed of media. The filters are aerated to satisfy the requirements of the micro-organism population and to maintain biological activity and growth.

Sludge generated in the secondary treatment process is thickened in the Dissolved Air Flotation (DAF) plant before being treated in the anaerobic digesters.


5. DISINFECTION

Treated wastewater is disinfected with ultraviolet (UV) light to destroy pathogenic bacteria. The process utilizes UV light, and therefore has no impact on the chemical composition of the water. UV disinfection is required from April 15 to October 15.

6. DISCHARGE

The final step in the wastewater treatment process is the return of clear treated water to Lake Superior. The effluent from the WPCP is discharged into the Kaministiquia River, approximately 400 metres upstream of Lake Superior.

7. SOLIDS TREATMENT AND COGENERATION

Sludge is produced as a by-product of the wastewater treatment process. Two types of sludge, primary and secondary, are processed in the anaerobic digesters.

Biogas contains approximately 60% methane (the combustible component of natural gas). The cogeneration system converts the biogas to electricity and captures the heat generated from the engine. The biogas can also be used in the plant boilers to generate heat.

Digested sludge is mechanically dewatered using centrifuges to separate the solids from the liquid to create a sludge cake. The centrifuges increase the solids content of the digested sludge from approximately 2% to 25%. The sludge cake is collected in bins and transported to the City’s SWRF for final disposal.


The TSS effluent concentrations remained below the ECA objective and limits for the entire year. See Figure 1 below for the monthly TSS and CBOD5 results.

WASTEWATER TREATMENT PROCESS SUMMARY

The WPCP must operate within the effluent limits outlined in the MECP Environmental Compliance Approval (ECA). The ECA lists effluent limits for the following parameters: Total Suspended Solids (TSS), CBOD5, Total Phosphorus (TP), pH and E. coli. In addition to the effluent limits, there are effluent objectives which are lower concentrations than the limits. The WPCP strives to produce effluent quality to meet these objectives. Total Ammonia Nitrogen (TAN) is currently listed only as an effluent objective. There are two objectives for ammonia, one for the freezing period (November 1 to March 31) and one for the non-freezing period (April 1 to October 31). E. coli has a seasonal limit and objective from April 15 to October 15. The following summarizes the performance and success of the plant relative to these limits and objectives.

Januar

y

Februar

y

March

April

MayJu

neJu

ly

August

September

October

Novem

ber

Decem

ber

25

20

15

10

5

0

Effluent CBOD ECA ObjectiveECA LimitEffluent TSS

Con

cent

ratio

n (m

g/L)

Figure 1: Monthly Effluent Results - TSS and CBOD5


The effluent total phosphorus monthly concentrations in 2020 were below the ECA limit for the entire year and below the ECA objective for the majority of the year. In February, the total phosphorous concentration in the effluent was at the objective. The primary coagulant dosage was increased to bring the total phosphorus concentration below the objective. The total phosphorus concentration in the wastewater entering the WPCP increased in February due to the dry weather and low wastewater flows. Refer to Figure 2 for the monthly effluent total phosphorus concentrations for 2020.

Figure 2: Monthly Effluent Results - Total Phosphorus

The effluent pH for the WPCP remained within the range outlined in the ECA as shown in Figure 3.

Figure 3: Monthly Effluent Results - pH

Januar

y

Februar

y

March

April

MayJu

neJu

ly

August

September

October

Novem

ber

Decem

ber

1.2

1

0.8

0.6

0.4

0.2

0

Effluent Phosphorus ECA ObjectiveECA Limit

Con

cent

ratio

n (m

g/L)

11

10

9

8

7

6

5

Effluent pH ObjectivesECA Limits

pH (S

U)

Januar

y

Februar

y

March

April

MayJu

neJu

ly

August

September

October

Novem

ber

Decem

ber


Figure 4: Monthly Effluent Results - Ammonia Nitrogen

BIOSOLIDS SUMMARY

The dewatered sludge generated in 2020 is presented in Figure 5. In 2020, 8,126 tonnes of biosolids (dewatered sludge) were hauled to the City’s SWRF by a contracted waste hauler. The biosolids are weighed before being buried with incoming solid non-hazardous waste on a daily basis. Dewatered sludge will continue to be direct buried at the City’s SWRF in 2021. The WPCP expects to generate approximately 9,000 tonnes of biosolids in 2021, assuming a similar wastewater flow.

Figure 5: Biosolids Shipped to Solid Waste & Recycling Facility

The monthly effluent results for total ammonia nitrogen remained below the ECA objectives for the year. See Figure 4.

Con

cent

ratio

n (m

g/L)

Januar

y

Februar

y

March

April

MayJu

neJu

ly

August

September

October

Novem

ber

Decem

ber

850800750700650600550500450

Tonn

es (T

)

2020 Biosolids Generated

Januar

y

Februar

y

March

April

MayJu

neJu

ly

August

September

October

Novem

ber

Decem

ber

ECA Freezing ObjectiveAmmonia ECA Non Freezing Objective

76543210


PLANT TREATMENT PROCESS SCHEMATIC

Secondary TreatmentPrimary Treatment

BAF – Biological Aerated Filter

C – Carbonaceous

N – Nitrification

DAF – Dissolved Air Flotation

Automated Sample Point

Headworks Bypass

PolymerBarScreens #1 to #4

Primary Clarifiers #1 to #4

BAF Fine Screens

Aerated Grit Tanks 1&2

Final Effluentto

KaministiquiaRiver

Ultraviolet Disinfection (Seasonal)

BAF “N”ParshallFlume

BAF “C”

Raw Sludge

To Sludge Blend Tank

Thickened Waste

Secondary Sludge

Main Pump Station Pumps

#1 to #5Screenings to Landfill Backwash

Waste Tank

Alum

DAF

Grit to Landfill

Raw Sewage

BackwashSupply Tank


Influent Pump Station (IPS)• Wet well #1 cleaning;• Wet well #1,2,3 scum removal;• Wet well #1 gate guide replacement;• Replace impeller and shaft

assembly for 600 HP pump;• New Parshall flume flow transmitter

and sensor installation.

Primary treatment• Annual maintenance on primary clarifiers;• Bar screen influent channel cleaning;• Primary distribution channel inspection;• Removal of vegetation in

Primary Bypass channel;• Replacement of Primary Clarifier #2

Raw Sludge Pump intake pipe.

Sludge and Dewatering System• Centrifuge #3 PLC controls upgrade;• Dewatering pump header replacement;• Thermal flare insulation

replacement and upgrade;• Sludge Blend Tank cleaning

and inspection.

INFRASTRUCTURE PROJECTS

As part of the Environment Division’s Asset Management Plan, many projects were carried out during 2020 to protect and improve the equipment and infrastructure.


Biological Aeration Filtration (BAF)• BAF filter #2 major service;• BAF filters partial excavation.

Heating and Ventilation (H&V)• IPS HVAC maintenance.

Buildings & Grounds• Plant settlement survey.

Cogeneration• Cogen heat recovery loop control

valve replacement;• Cogen after cooler overhaul;• Cogen major servicing.

Electrical & Instrumentation Systems• Infrared scan arc flash window

installations;• SCADA computer software upgrades,

including alarm and reporting upgrades;• LED lights installed on clarifier

light standard;• Load bank testing and annual service

of generators and remote station;• Admin Building & DAF transformer

emergency power transfer switch installation.

Disinfection System• Curtains installed at UV process discharge.

Wastewater Collection – Pollution Prevention Control Plan• Separation of approximately 2 km

of sanitary and storm sewers;• Majority of the sewer separation work

occurred in the Syndicate Avenue area;• Combined sewer overflow (CSO) on Syndicate

Avenue at Brodie Street was decommissioned.


WASTEWATER SYSTEM SUMMARY 2020 ATLANTIC AVENUE WATER POLLUTION CONTROL PLANT

520 km

108,000people

4 remote lift stations

of sanitary sewer

Serving over

INFRASTRUCTURE

5 km of combined sewer Over 23 billion litres

9,000 Olympic sized swimming pools

of wastewater treated in 2020

Equivalent to over

WASTEWATER TREATED

2,950 MWh of electricity generated on-site

Over

RESOURCES

was used to generate electricity or heat on-site buildings

92% of gas generated in digesters

$5,000+

17

samples analyzed by in-house lab

Operated

OPERATIONS

licensed operators

365 days/ year

24 hours/day

100% 8,100 of effluent limits were achieved

Over

ENVIRONMENTAL PROTECTION

Over 90% removal efficiency for: Tonnes of solids removed from effluent stream

Equivalent to the weight of

42 adult moose a day • Ammonia

• Suspended Solids• Phosphorus

• Carbonaceous biochemical demand


CALIBRATION & MAINTENANCE OF MONITORING EQUIPMENT

Calibration and maintenance of the effluent monitoring equipment and automatic samplers were carried out by the Environmental Inspector and Laboratory Technicians. The influent flow measuring device is verified for accuracy by Plant Electricians on a routine basis and calibrated by a third party on an annual basis.

SEWER USE CONTROL PROGRAM

The Hauled Sewage Monitoring Program recorded a total of 523 loads of processed water and septic tank wastes, which accounted for 7.04 million litres received and processed at the WPCP in 2020.

The Over-Strength Discharge Program, provided through the City’s Sewer Use By-law, allows participating industrial users to discharge effluent which contains excess phosphorous, CBOD5, and total suspended solids higher than the limits outlined in the By-law. An additional fee, based on these parameters, and on the actual treatment cost of the loading above the By-law limits, is then applied to these industries. Industries approved to discharge are issued agreements, as required.

The City’s Environmental Inspector responded to 6 reports of possible spills or pollution complaint calls in 2020. Each of these issues was addressed and remediated as required.

COMPLIANCE & QUALITY CONTROL LABORATORY

The Compliance & Quality Control (C&QC) laboratory supports the process control testing for the WPCP. Under the direction of the Chief Chemist, Laboratory Technicians carry out operational analytical requirements, as outlined in the Environment Compliance Approval (ECA). The testing includes, but is not limited to the following parameters: carbonaceous biochemical oxygen demand (CBOD5), total suspended solids (TSS), total and soluble phosphorous (TP and SP), total solids (TS), volatile solids (VS), volatile acids, ammonia, chemical oxygen demand (COD), capillary suction time (CST), alkalinity and ultraviolet transmittance (UVT). The laboratory has a quality control and assurance program in place. Additionally, the calibration and verification of the analytical equipment used in the laboratory is confirmed annually.

Lastly, an external accredited laboratory conducts tests for metals, COD, ammonia and total Kjeldahl nitrogen (TKN). Also, the C&QC laboratory provides analytical support for the SWRF and the Sewer Use Control Program.


BY-PASS EVENTS

During 2020, there were no combined sewer overflows at the duckbill located in the McVicar Creek.

Throughout 2020, the WPCP experienced a number of secondary and partial secondary by-pass events. Over the course of the year, 18,900 cubic metres of wastewater received primary treatment and by-passed the secondary treatment plant before entering the Kaministiquia River. An additional 25,600 cubic metres of wastewater received primary and partial secondary treatment before being discharged to the Kaministiquia River. High wastewater flows, caused by the spring snow melt and heavy rainfall events, accounted for over 95% of the volume of the partial secondary by-passes. Loss of utility line power accounted for 64% of the wastewater volume that bypassed secondary treatment. Equipment failure accounted for the remaining 36% of the wastewater volume that by-passed secondary treatment. As required by the WPCP’s ECA, the by-passes were disinfected. All by-pass events were reported to the MECP, Thunder Bay District Health Unit and Environment Climate Change Canada following the established reporting protocol.

COMPLAINTS

The WPCP received one public inquiry in 2020 related to a foul odour emanating from the secondary treatment process. This occurred while maintenance activities were occurring and a filter was out of service and drained. The filter was filled with water and the odour dissipated.

“Island Drive Bridge” by Sean Randall


DATA TABLES

Table 1: Flows Received

Month Influent Volume

(ML)

Total Precipitation

(mm)

Maximum Daily Flow

(MLD)

Average Daily Flow

(MLD)

January 1,304 29 115 42.1

February 1,213 7 110 41.8

March 1,444 22 120 46.6

April 2,127 10 100 70.9

May 2,038 35 105 65.7

June 2,228 47 142 74.3

July 2,246 53 142 72.5

August 2,258 94 126 72.8

September 2,232 70 234 74.4

October 2,489 68 152 80.3

November 2,286 22 139 76.2

December 1,543 29 122 49.8

Total 23,409 487

Average 1,951 41 63.9

Table 2: Plant Effluent Quality – Monthly Average Concentration

Month CBOD5 (mg/L)

TSS (mg/L)

TP (mg/L)

E. coli (#/100 mL)

TAN (mg/L)

pH (SU)

Temperature (°C)

Limit 25 25 1 200 No Limit 6.0 to 9.5 No Limit

Objective 15 15 0.5 150Apr 1 - Oct 31: 3.0

Nov 1 to Mar 31: 5.0 6.5 to 8.5 No Objective

January 9.9 9.4 0.4 3.7 7.3 11.6

February 10.4 10.4 0.5 4.1 7.2 11.0

March 8.6 9.1 0.4 3.0 7.2 11.6

April 5.0 5.6 0.2 52 0.4 7.6 10.9

May 5.4 5.4 0.2 81 0.5 7.4 12.5

June 4.7 5.4 0.2 60 0.5 7.5 15.5

July 5.7 7.2 0.3 80 0.9 7.4 18.3

August 4.0 5.7 0.3 85 0.6 7.5 18.5

September 4.3 6.0 0.2 35 1.4 7.5 17.0

October 4.8 6.4 0.3 47 1.5 7.5 16.4

November 5.4 5.1 0.2 0.7 7.4 14.0

December 8.1 7.5 0.3 1.7 7.3 12.4

Average 6.4 6.9 0.3 60 1.6 7.4 14.1


Table 3: Plant Effluent Quality – Monthly Average Loading

Month CBOD5 (kg/d)

TSS (kg/d)

TP (kg/d)

Limit 2112.5 2112.5 84.5

January 444.5 393.6 17.7

February 439.0 435.9 22.6

March 399.6 422.3 18.7

April 343.5 399.8 16.1

May 324.3 351.0 14.4

June 361.0 393.6 15.4

July 408.8 515.4 22.1

August 292.9 392.6 19.3

September 321.7 447.1 18.9

October 402.3 498.8 19.4

November 405.2 373.5 14.9

December 414.3 376.6 16.3

Average 379.8 416.7 18.0

Table 4: Sludge Dewatering Results

Month Sludge to Dewatering

(m3/day)

Total Sludge Dewatered

(m3)

Biosolids Generated (Tonnes)

January 306 9,484 627

February 280 8,133 579

March 261 8,101 621

April 287 8,613 777

May 255 7,896 703

June 275 7,158 641

July 296 7,688 693

August 231 7,148 649

September 243 7,302 702

October 281 8,718 787

November 257 7,700 670

December 277 8,579 678

Average 271 8,043 677

Total 96,521 8,126

Staff Organization

Infrastructure and Operations

General Manager - Kerri Marshall, P. Eng., MBA, FEC

Policy & Research Analyst – Julie Wiejak

Sustainability Coordinators – Amy Coomes, Summer Stevenson (Acting)

Climate Adaptation Coordinator – Jacob Porter

Communications Officers – Amanda Nason, Wendy O’Connor (Acting)

Technology Management Specialist - Henry Connor, B. Eng.

Environment Division

Water Pollution Control Plant

Plant Superintendent – Bob Bates, P. Eng.

Supervisor, Maintenance – Mike Brown

Supervisor, Operations – Mark Wilson

Accounting & Administration Clerk – Kristie Fisher

Chief Operator, Electrical – Dan Fulton

Chief Operator, Maintenance – Sal Piccolo

Chief Operator, Operations – Rick Sutton (Acting)

Environmental Inspector – Patrick McGuire

Janitor/Handyworker – Darrin White, Mario Colistro

Laboratory Technicians – Julie Carlin, Keenan Colosimo

Millwrights – Gord Belanger, Thane Gagnon, John Hrycyk, Mike Noga, Warren Perry

Operators – Jeff Coull, Rick Sutton, Patrick Melanson, Chris Unick, Phillip Kennedy, Shane Bureau, Patrick Melanson

Plant Electricians – Brian Dobson, Ron La Froye, Andreas Makrides

Relief Operator – Daniella N de Lima

Director – Michelle Warywoda, P. Eng.

Administrative Assistant - Lynae Grace

Chief Chemist – Ian Morgan, Ph.D., P. Chem., C. Chem.

Manager – Compliance & Quality Control – Tony Santos

Planning & Research Analyst – Dan Currie, C.E.T.

Process Engineers - Lindsay Menard, P.Eng., PMP, Walter Turek, P.Eng.

Training & Quality Assurance Coordinator – Shelby Jaspers

Water and Wastewater Engineer – Tom McConnell, P.Eng.

WATER POLLUTION CONTROL PLANT CITY OF THUNDER BAY ENVIRONMENT DIVISION 901 ATLANTIC AVE THUNDER BAY ON P7C 5K4

TEL: (807) 625-3370

THUNDERBAY.CA

WATER POLLUTION

CONTROL PLANT

wastewater treatment - thunder bay

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