A large scale system for supplying water to the City of Winnipeg began in 1913 when Shoal Lake, at the Manitoba-Ontario boundary, was chosen as the source of Winnipeg's water supply. An aqueduct was built to move water to the city from Indian Bay on Shoal Lake, and a complex series of pipes, pumps and reservoirs was constructed to distribute the water throughout Winnipeg. Once used, the wastewater was released directly into the City's rivers, without being treated.

During the 1930's, the public became concerned that the untreated wastewater, also called sewage, polluting the City's rivers was causing health problems. This led to the construction of Winnipeg's first sewage collection and treatment system, with 12 kilometres of collector sewers, 24 pumping stations and the North End Sewage Treatment Plant.

The North End Sewage Treatment Plant was opened on October 25th, 1937. Winnipeg became the first city in Canada of over 100,000 people to install sewage treatment. Since then the plant has been upgraded and expanded to become the North End Water Pollution Control Centre. It is the largest of three wastewater treatment facilities serving the City of Winnipeg, and provides primary and secondary activated sludge treatment, and sludge processing.

The North End Water Pollution Control Centre (NEWPCC) treats about 70% of Winnipeg's wastewater. It services most of the old City of Winnipeg, part of St. Boniface, all of East, West, North and Old Kildonan, Transcona and part of St. James. The rest of the city is serviced by the West End Water Pollution Control Centre (WEWPCC) in Charleswood and the South End Water Pollution Control Centre (SEWPCC) in St. Vital.

This web site focuses on the wastewater treatment processes at NEWPCC. However, the processes used at the SEWPCC and WEWPCC are very similar, with the exception that these plants are smaller and have no sludge handling capability. The City of Winnipeg, a pioneer in wastewater management, has early on determined that it is more cost effective to centralize sludge treatment processes, so that the SEWPCC and WEWPCC haul their sludge using large tanker trucks to the NEWPCC for processing. The sludge treatment process is described further in this site.

Item	NEWPCC	SEWPCC	WEWPCC	Total
Design Population	395,000	169,000	98,000	662,000
Population Served	374,000	160,000	86,000	620,000
Design ADWF*	302 ML/d	59 ML/d	32 ML/d	393 ML/d
Actual ADWF	160 ML/d	50 ML/d	27 ML/d	237 ML/d
Orig. Const. Year	1937	1974	1994
Plant Analytical Performance Data

Notes: ADWF = Average (Winter) Dry Weather Flow. ML/d = Mega-Litres per day.
Approximate 2002 data.
*Source: Conceptual Design Reports.

SEWAGE COLLECTION SYSTEM

A vast system of underground sewers, force mains and pumping stations are needed to collect the wastewater from the homes of the city's residents and deliver it to the interceptor sewers, then to the water pollution control centres.

Individual sewers (service connections located 2.5 meters below ground) from homes and businesses carry the flow of wastewater into lateral sewers in each neighborhood. The wastewater from the lateral sewers moves into the trunk sewers located 6 to 9 meters below ground. Pump Stations, also called Lift Stations, raise the wastewater from the trunk sewers into the main interceptor sewers. The wastewater flows by gravity through these large interceptor sewers, which are up to 50 feet deep and 60 inches diameter, into the treatment plants.

About 2400 kilometres of sewers and interceptors, and 72 pumping stations are needed to carry the wastewater to the water pollution control centres. The pumping stations all have automated equipment alarms, and in the event of a breakdown, alarms are transmitted to a 24 hour dispatch center for immediate response, to prevent pollution to the rivers.

Approximately 50% of the city is serviced with Combined Sewers, which discharge diluted wastewater to the rivers during significant rainstorm events. But thanks to the efficient operation of the Collection System, the City treats Over 90% of all the wastewater generated in the City. The Collection System is also responsible for the important function of Flood Pumping during the annual high river event.

THE IMPORTANCE OF TREATING WASTEWATER

The role of the Water Pollution Control Centres is to help control the pollution of the City's rivers. It does this by treating wastewater to remove inorganic solids such as sand and gravel, and by reducing the amount of organic material before it is released to the City's rivers. Treated wastewater is 90-95 percent free of organic material present in sewers (as measured by the standard 5-day carbonaceous Biochemical Oxygen Demand (CBOD5) analysis).

The process used to treat sewage, also called wastewater, is very similar to the natural decomposition that would occur if wastewater was released directly into Winnipeg's rivers. Bacteria would feed on the organic materials and break them down, using up the oxygen in the water. This would decrease the oxygen in the river, so that healthy populations of fish and aquatic life could not live there. As these organic materials decomposed and caused septic conditions, they would also give off unpleasant odors and create a public health concern.

Speeding up and controlling the decomposition of the organic material in sewage inside the treatment plant helps to maintain a healthy environment for fish and other aquatic life in Winnipeg's rivers. The odors produced through this decomposition are also contained within the treatment plant. Without treatment, the organic material in the wastewater would be released to the river, where it would decompose and reduce oxygen levels in the river to a point where they may become lethal to biota.

PROCESS CONTROL:
THE DISTRIBUTED CONTROL SYSTEM (DCS)

The DCS is the nervous system of the treatment plant. At the NEWPCC, as well as the other plants, an intricate network of specialized computers, called the DCS, accomplishes control of the treatment process. Fully trained Operators (certified by the Association of Boards of Certification) can decide on a process strategy, input setpoints into the computer, and the DCS operates valves, pumps, mixers, fans, controls, etc. throughout the plant to maintain the setpoints on a continuous basis. The DCS does this by monitoring thousands of sensors located throughout the plant, making calculations and adjustments prescribed by the operators and a specialized group of process control analysts, and alerting the operators of any problem conditions.

The DCS also saves historical operating data, and can plot or trend this data on request. The operators can monitor and control the entire plant from a total of 18 workstations located throughout all three plants, which is why the control is called "distributed". This is a big advantage in large plants.

The Distributed Control System also includes an inter-plant Wide Area Network (WAN). The operators can monitor the other plants from any plant. This way, only the NEWPCC is manned 24 hours/day, and the shift operators there monitor the SEWPCC and WEWPCC during nights/weekends. The DCS and long-term historical data are also "web-enabled", so that they will be accessible over the Internet once this feature is set up.

(Click on figure for larger scale) (For PRINTING INSTRUCTIONS, click HERE!)

THE MAIN BUILDING

The Main Building of the NEWPCC contains the administrative offices and the Laboratory Services Division, in addition to the main pumps. Laboratory Services provide testing and control services for pollution control as well as water quality monitoring and associated research. (See section: "Laboratory Services Division")

Sewage enters the treatment plant by flowing through the main interceptor (1, see figure below) into a wet well (2), 16 meters below ground level in the Main Building. In addition, leachate from landfills is trucked in and dumped here for treatment. Leachate is a high strength liquid which collects at the bottom of landfills and must be removed to prevent groundwater pollution. Also, septage from the septage haulers is dumped here for treatment.

From the wet well, the sewage is drawn into three pump wells (3), each having two pumps. The number of pumps being used at one time depends on the amount of wastewater flowing into the plant. Rainfall, run-off from spring thaw and the time of day all affect the amount of flow entering the plant.

The pumps are programmed to handle the flow coming into the plant and lift it above ground level into a discharge chamber (4). From this point, all the main flow through the rest of the treatment plant occurs by gravity. From the discharge chamber it flows into the sewage conduit (5). The sewage moves through the conduit to the first stage of treatment in the Pre-aeration and Grit Removal Building.

PRE-AERATION - SCREENING - GRIT REMOVAL

As the sewage flow enters the Pre-aeration and Grit Removal Building, it is divided into four covered tanks (6, see figure below). Before entering these tanks, the sewage passes through bar screens (7) with 12 mm openings. These screens remove large objects such as sticks, rags and garbage. These materials are conveyed to trucks and taken to a landfill.

After passing through the bar screens, the sewage is gently agitated with air in the first part of the tank. This helps to remove heavier inorganic materials such as sand and gravel, called grit, while keeping organic matter in suspension for treatment. Once the grit has dropped to the bottom of each tank, it is removed by a clam-shell bucket (8) and placed into trucks (9-10) for disposal at a landfill site.

In the second section of the tanks, air is bubbled more vigorously through the wastewater. This is known as pre-aeration. It helps to remove foul-smelling gases like hydrogen sulfide (rotten egg smell) which develop in the sewers when the material in the wastewater begins to break down. These gases are vented to the atmosphere through tall (50 metre) chimney-like stacks.

Waste (Waste Activated Sludge) from a later stage of the treatment process (11) is added to sewage after (or before) passing through this building, before the sewage goes onto the primary stage of treatment.

*Each tank is 46 m x 9.1 m x 4.6 m average depth)

PRIMARY TREATMENT

Primary treatment is the first step in separating the fine solid material from the liquid wastewater. Primary treatment removes about one half of the solids and one third of the organic pollutants from the wastewater flow.

Primary treatment takes place in five large settling tanks called primary clarifiers (13, see figure below). Sewage coming from the Pre-aeration and Grit Removal Building (12) flows into these five tanks where it stays for at least two hours. During this time about 50 percent of the fine solid waste material (known as suspended solids) in the wastewater settles out and sinks to the bottom of the tanks. Once they have settled out, these solids (called Primary Sludge) are collected from the bottom of the tanks by large mechanical scrapers. These scrapers move the sludge into hoppers or bins at the bottom of each tank. The sludge is then pumped to another area (15) for further treatment (see "Sludge Digestion").

Surface scum or grease is skimmed off the top of each tank and taken by a separate system of pumps and pipes for further treatment with the sludge.

The liquid left in the tanks is called "settled sewage". It flows over the edge of the tanks and onto the secondary treatment stage (16). Primary treatment is now complete.

SECONDARY TREATMENT

Secondary treatment is the second step used to remove remaining organic matter from the wastewater before it flows from the treatment plant to the river. This process is generically called the Activated Sludge Process.

Oxygen Reactor Tanks

In the first part of secondary treatment, the settled sewage (16, see figure below) flows into six oxygen reactor tanks (17) arranged into three trains. Here the incoming wastewater is vigorously mixed with high-purity oxygen (21) and sludge (24) (called return activated sludge, RAS) containing large amounts of bacteria. In nature, these bacteria need oxygen (aerobic bacteria) to survive and feed on organic material. This natural process is speeded up in the oxygen reactors where the bacteria in the sludge use the high-purity (90-95% pure) oxygen to feed on the organic material in the settled sewage.

High-purity oxygen for the oxygen reactor tanks is produced in the cryogenic air separation plant (19) on site. This plant is operated by a private company under a long-term contract.

Final Settling Tanks (Secondary Clarifiers)

From the oxygen reactor tanks the mixture of bacteria and water (called "mixed liquor") flows (18) into the final settling tanks (23), also called final clarifiers. Here the bacteria laden sludge settles to the bottom of the tanks. After settling is complete, the water in the tanks is 90 - 95% free of polluting materials. This final effluent can now be safely released into the river (25).

The settled bacteria laden sludge is now called activated sludge, because it has been "activated" with bacteria which clean the wastewater. This sludge is removed from the bottom of the tanks by underwater scrapers and pumps. Most of the activated sludge is returned (24) to the oxygen reactor tanks to supply the bacteria needed for the secondary treatment. This portion is called Return Activate Sludge (RAS). The excess, called Waste Activated Sludge (WAS), is sent to be mixed with the effluent from the pre-aeration stage, where it flows to the primary clarifiers. There, the Waste Activated Sludge will settle out with the Primary Sludge, and in doing so, it will thicken from less than 0.5% to over 3% solids. This process, thickening the WAS with Primary Sludge, is called "co-thickening". The settled sludge is then pumped to the digesters.

Oxygen Reactor Facts	Secondary Clarifier Facts
Number of oxygen tanks = 6 (30130 m³ total)	Number of clarifier tanks** = 26
Number of trains* = 3	Total hydraulic capacity = 600 ML/d
Amount of oxygen used = 33 tonnes/day, 90 t/d capacity
Mixed liquor suspended solids = 2000-3000 mg/l

*each tanks is 70 m x 17.5 m x 4.5 m deep. Total volume = 31,200 m3
**(10 circular square clarifiers are 20 m diameter; 16 rectangular clarifiers are 70.5 m x 9.1 m. Total volume = 41, 275 m3

SLUDGE DIGESTION

Sludge from the bottom of the primary clarifiers (15, see figure below) is sent to the sludge digesters (26). Sludge from the South and West End Plants is trucked in and added here as well, because those plants don't have digesters. In the digesters, bacteria that do not need oxygen (anaerobic bacteria, the same ones as in your large intestines) begin to feed on the sludge in the oxygen-free environment inside the digesters. Heat exchangers (27) are used to regulate the temperature inside the digesters, keeping it around 38 Celsius (same as your body temperature). The technical name for this process is "Mesophylic Anaerobic Digestion".

The content of the digesters is mixed continuously. The bacteria feed on the sludge for 10-20 days and decompose (stabilize) it. This reduces the odor and organic matter in the sludge. The digested sludge (called "biosolids"), which is still mostly liquid, is stored in holding tanks (29) before it is sent to the dewatering system (3) where some of the liquid is removed.

"Sludge gas" (also called "Biogas") consisting of about 65% methane and 30% carbon dioxide is produced by the anaerobic bacteria during digestion. This gas is highly combustible, so it is stored (33) in the gas storage sphere, and used as fuel in boilers to heat (35) the treatment plant, as well as the sludge in the digesters. Excess methane is released using the waste gas burners (34). In this manner, all the methane, a serious greenhouse gas, is converted to carbon dioxide and water vapor. On very cold winter days, when there is not enough biogas produced to heat the plant, natural gas is also used (36).

Sludge Digestion Facts
Number of digesters* = 6	Number of holding tanks = 4
Total volume of the digesters = 44,800 m3	Total holding capacity = 15,400 m3
Number of boilers = 5	Gas sphere volume = 2,065 m3
Boiler capacity (total) = 64 Giga Joules	Biogas Production: 35,300 m3/d

BIOSOLIDS DEWATERING SYSTEM

Digested sludge, called "Biosolids", are pumped (30, see figure below) from the holding tanks to centrifuges (38) in the dewatering building. Before it enters the centrifuges, special organic chemicals known as polymers are added (44) to aid in the separation of liquids and solids. The centrifuges spin the sludge at very high speeds to separate the liquid from the solids.

Once they are separated, the liquid (called centrate), which has a high concentration of ammonia, is returned to the main interceptor to enter the plant for treatment. The dewatered biosolids (called cake) is pumped through the biosolids cake line (40) to the biosolids cake storage bins (42). The biosolids cake is temporarily stored in these covered bins until it is loaded onto trucks (43) inside the dewatering building. It is then taken to agricultural land where it is applied as fertilizer.

Biosolids are a relatively stable product, and rich in nutrients such as nitrogen and phosphorus. This makes it a valuable fertilizer for agricultural lands. The City of Winnipeg operates a successful program called "WinGRO" where dewatered biosolids are recycled by applying it to agricultural land to fertilize and condition the soil.

Sludge Dewatering Facts
Number of centrifuges = 6	Number of cake pumps = 6
Capacity = 19 - 22 L/s/unit	Power = 75 HP
Power = 200 HP each	Operating Pressure = 1200 - 4480 kPa
Bowl Speed = 2500 RPM (2500 G's)	Capacity = 4.4 L/s/unit
Typical solids content = in 3 - 4%; out 23 - 29%	Number of biosolids cake bins = 3
Biosolids Production: 135 "wet" tonnes/day at 25% solids	Total holding capacity = 165 tonnes x 3 = 495 tonnes

THE WinGRO PROGRAM

What is WinGRO?

WinGRO is the program operated by the City of Winnipeg under which dewatered biosolids from the North End Water Pollution Control Centre (NEWPCC) are hauled to and spread on agricultural land. The WinGRO program is operated in compliance with terms and conditions prescribed in a License issued under the Manitoba Environment Act to the City of Winnipeg. Extensive research has been completed to ensure that the WinGRO program is safe and beneficial to the environment. The City, in collaboration with academic and private entities, is continuously researching technologies to improve the program.

Why do farmers want WinGRO?

Although Wastewater Treatment Plants remove pollution from wastewater, their final effluent contain bacteria which are pathogenic to humans if ingested. At the NEWPCC, conceptual design of final effluent disinfection is underway and is expected to be implemented in 2006. At the SEWPCC, final effluent disinfection is accomplished using Ultra-Violet Radiation (UV Disinfection), commissioned in 2000. At the WEWPCC, disinfection is accomplished by diverting the final plant effluent through large open basins, where the pathogens are killed naturally by solar radiation.

LABORATORY SERVICES DIVISION

The Laboratory Services Division, located in the Main Building, plays an important role in the operation and maintenance of the City's water supply and wastewater treatment systems. The chemists and technicians provide technical services to the Operations Divisions to ensure the water supply and wastewater treatment processes meet government standards for water quality. The Analytical Services Branch staff are responsible for monitoring the City's water supply and water distribution system, all three wastewater treatment plants, industrial wastewater and water quality in the rivers and streams in Winnipeg. The City's laboratory ranks among the finest in the country, and is nearing completion of C.A.E.A.L. accreditation.

Wastewater is regularly tested for pH, dissolved oxygen (DO), total organic carbon (TOC), biochemical oxygen demand (BOD), suspended solids, heavy metals, nitrogen, and phosphorus, among others. Digester gas is also regularly tested for carbon dioxide and methane. Laboratory staff run calibration checks on the equipment and test methods used by the Operations Division. The Research Branch carries out applied research on the treatment processes to help improve treatment.

There are many substances which, if dumped into the sewer system, would impair wastewater treatment processes. The Industrial Waste Control Branch of the Laboratory Services Division monitors industry and homeowners for compliance with The City of Winnipeg Sewer By-law 7070/97 (Adobe Acrobat required... see related links below). The Industrial Waste Control Branch enforces the Sewer By-law in such areas as restricted materials, septic fields, and wastewater hauling. The Branch also responds to hazardous spills affecting the City's sewer system and assists the Solid Waste Division in approving and rejecting the disposal of hazardous and special wastes at the Brady Road Landfill.

The Laboratory Services Division provides accurate test results to ensure the quality of the water supply and the wastewater being released to the rivers. To do this the laboratory must keep up with the latest developments in analytical chemistry and use advanced instrumentation for collecting samples and chemical testing.

If you are interested in typical plant performance analytical data, click here.

WATER QUALITY IN WINNIPEG'S RIVERS

The Laboratory Services Division routinely monitors the rivers and streams in Winnipeg. This work includes studies on the quality of river water and the impact of wastewater released from the treatment plants on the water in the City's rivers.

These studies show that Winnipeg's efforts to control pollution of the City's rivers from wastewater and sewage have improved the quality of river water. Today, there is abundant aquatic life in the city's rivers which was not there in the 1930's. Each year master angler awards are issued for fish caught in the Red River. The fish caught include channel catfish, walleye, bullhead, burbot, carp, freshwater drum, goldeye, northern pike, perch, rock bass, and white bass.

As the City grows, it will face new demands for wastewater treatment. The Water and Waste Department of the City studies new technologies for treating wastewater and controlling pollution. In addition to many other programs, the department is investigating ways to reduce Combined Sewer Overflows (CSO's) and to improve the quality of the final effluent from its treatment plants. We are also investigating alternative biosolids management and treatment technologies. These efforts will help protect and enhance the rivers for the health and enjoyment of all Manitobans.

Wastewater management is an expensive enterprise for any large city. For 2000, the total cost for providing wastewater services in Winnipeg was approximately $74 million. This cost is not only for the supplies and the operators, mechanics, technicians, electricians, and programmers needed to directly operate/maintain the facilities, but also for all the support staff such as engineers, technologists, laboratory, customer services and corporate support. In addition, the City borrows money to pay for capital expenses, such as treatment plant expansions (over $200 million in the past 20 years), which must be paid back. For a breakdown of these costs, click here.

"Wastewater Services" is a utility, much like the more familiar gas and electric utilities. The cost for wastewater management is paid for by the utility's customers. Each customer has a water meter, which is used to determine how much water is used. The meter is read quarterly, and the City sends an invoice to the customer. The invoice indicates how much water was used for the past quarter and the cost for the water. The same invoice also indicates the cost for wastewater services, based on the same water meter reading. Contrary to popular belief, Wastewater Services are not paid by municipal taxes.

In general, the sewer rate is determined by dividing the total annual cost of providing wastewater services, by the total annual amount of water used by the community. The current (2004) rate is $3.11 per 100 cubic feet.

Our motto:
"When you flush, think of us!"

Revisions: (Sorry... I can't recall when I started this site...)

May, 2002: Added "History" table

December, 2002: Fixed broken links & added numerous links; added paragraph on Industrial Waste Branch; added "Other Resources", "Wastewater Process Basics" and "Cost" sections; added DCS screenshots; Chlorine gas is no longer used.

January, 2003: Corrections to history ADWF data; added 1937 plant photo & minor enhancements.

May, 2003: Added counter

February, 2004: Updates, clarifications here and there, and fixed links throughout.

Added printing instructions for high-res. schematics. Let me know if you find anything wrong!

Comments, corrections, bad links? Please simply call Paul Lagassé. P.Eng., at 204-986-4434

This site has evolved SOLELY as a result of your questions and comments! Please Call!

Copyright Notice: This site is NOT copyrighted. It's purpose is for the propagation of information and knowledge on Wastewater Management, and the copying/use/modification of the material herein is not only allowed, but encouraged. The EXCEPTION to this is the section on Centrifuges, which is the sole property of Alfa Laval, and any use thereof requires their permission.

Disclaimer: (I hate to do this, but...) The information contained on this website is to the author's best information, knowledge, and belief. The author accepts no responsibility for the accuracy or use of the information contained herein. The author accepts no responsibility in any way for external links.

Main Pump Facts
Number of main pumps	6
Total installed power	3960 HP (1060 ML/d)
Firm design capacity (with the largest pump out of service)	3100 HP (860 ML/d )

Pre-Aeration & Grit Removal Facts
Number of bar screen	4
Number of grit tanks*	4
Total tank volume	1925 m3
Hydraulic capacity	280 ML/d/tank

Primary Treatment Facts
Number of tanks *	5
Total volume	24,300 m3
Total ultimate flow	830 ML/d

City of Winnipeg Water and Waste	Winnipeg Sewer Bylaw
Current River Levels at Winnipeg	Manitoba Water & Wastewater Association
City of Edmonton Drainage Services	Western Canada Water and Wastewater Association
City of Calgary Wastewater & Drainage	Saskatchewan Water and Wastewater Association
City of Ottawa Sewers and Wastewater	Alberta Water & Wastewater Operators
Ville de Montréal station d'épuration	Water Environment Association of Ontario
City of Toronto Water & Wastewater	Regional Municipality of Halton
Canadian Water and Wastewater Association	American Water works Association
Canadian Water Resources Association (Man.)	Northwest Biosolids Management Association
Association of Boards of Certification (ABC)	Water Environment Federation (WEF)

WINNIPEG'S WASTEWATER TREATMENT PROCESS

Our motto: "When you flush, think of us!"

Our motto:
"When you flush, think of us!"