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Wastewater treatment online tour


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Calgary has three wastewater treatment facilities:

  • Fish Creek Wastewater Treatment Plant
  • Pine Creek Wastewater Treatment Plant
  • Bonnybrook Wastewater Treatment Plant

Together, these treatment plants meet the wastewater and sewage needs of more than one million Calgarians each day. We invite you to take the wastewater treatment tour.For detailed descriptions of the recovery process, click through the images in the following diagram and learn more about Wastewater Treatment.

Collection Pump Station Headworks Primary Clarifiers Bioreactor Secondary Clarifier Disk Filter UV Disinfection Back to the River Gravity Thickeners Fermenters Digester Biosolids Dewatering Liquid Stream Solid Stream

Liquid Stream

Collection System

When water runs down a sink, drain or toilet, it becomes wastewater. Calgary has a system just for wastewater that moves it by gravity and pumps it to one of three treatment plants.

Protect your plumbing, our wastewater system and the environment

Putting fats, grease and oil down the sink can clog your pipes. Objects like dental floss, tissue and rags can lead to sewer backups. See a full list of items that can’t go down sinks, drains and toilets.

Pump Station

Pump stations in Calgary move wastewater through the sewer system to the plants.


When wastewater reaches a plant, it passes through screens that remove large materials such as plastic bags, toilet paper, sticks and tennis balls.

The water then travels into grit tanks where heavy items settle to the bottom. We take these materials to one of Calgary's three landfills. From this point, the water flows by gravity to the Primary Clarifiers.

Primary Clarifiers

Water is sent to large open-air tanks called primary clarifiers. It takes about three hours for water to pass through the tanks, and during that time solids settle to the bottom becoming sludge. Oils, grease and fats are skimmed off the top.

The sludge and skimmed waste is pumped to digesters for thickening and decomposition. This is the sludge-handling process. The water from these tanks goes to the bioreactors.


These large open-air tanks mix in high doses of micro-organisms. The micro-organisms eat nutrients like phosphorus and ammonia, and organic material. After about seven hours, the water flows to the secondary clarifiers.

Secondary Clarifiers

Water enters the secondary clarifiers, where it is held for another seven hours. Micro-organisms settle to the bottom of the tank, where they are recycled back to the bioreactor.

The cleaner water flows to a weir around the edge of the clarifier and is sent to the filtration and disinfection (U.V.) building.

Disk Filters

At the Pine Creek plant, treated water flows through cloth-media disk filters, improving quality by reducing solids, phosphorus and algae before moving on to disinfection.

UV Disinfection

Treated water is exposed to ultraviolet light. This light disrupts the micro-organisms' genetic material and makes them unable to reproduce and cause disease.

This kind of disinfection adds no chemicals to the water before returning it to the Bow River.

Back to the River

We return the water to the Bow River. It’s clear, colourless, high in dissolved oxygen, and very low in solids, phosphorus, ammonia, nitrogen and disease causing micro-organisms.

Our laboratories work seven days a week, 365 days a year. We collect samples at all stages of treatment and in the biosolids handling program, including Calgro. Our water meets the high standards set by Alberta Environmental Protection.

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Solid Stream

Gravity Thickeners

Sludge from the primary clarifiers passes to gravity thickeners for more settling. This thickens the sludge more before it’s pumped to either the digesters or fermenters.


Sludge sent to the fermenters is thickened and some is used to provide nutrients for the microorganisms in the bioreactors. The remaining sludge is pumped to the digesters.


Sludge enters warm oxygen-less digesters where, over a period of 25 days, bacteria breaks down complex organic materials into water, methane and carbon dioxide.

The digested sludge, now called biosolids, becomes less smelly and many disease-causing organisms are destroyed. We then pump the biosolids to our Shepard Lagoons.

Biosolids Management Program

Our biosolids management program recovers and recycles nutrient-rich organic matter for composting and agricultural purposes.

In the spring and summer, the biosolids go to the Shepard Lagoons to settle out for about six weeks. After settling out, the final product is a nutrient-rich resource ready for our Calgro program. It is transported by truck to agricultural lands where it is applied using a terrakenny. Farmers who are enrolled with our Calgro program use the organic matter and nutrients for crops such as cereal grains, trees, sod, small oilseeds and dried legumes. This program has been running for more than 30 years.

In the fall and winter months, much of the biosolids go to the de-watering facility where the water is removed. The remaining water is eventually pumped back to the wastewater treatment process to be treated and returned to the river, and the de-watered biosolids go to the composting facility to be further processed for about 60 days, producing a high quality Category A compost.

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Wastewater Treatment Tour