Let’s Explore Wastewater Treatment (brochure)
Download a printable version of the wastewater treatment process brochure.
Wastewater Treatment Plant - Robert O. Pickard Environmental Center
The Robert O. Pickard Environmental Centre (ROPEC) is located in the city's east end, right next to the Ottawa River. Using an extensive sewer system, all of the wastewater is collected from homes and businesses between Stittsville, Orleans and Manotick.
Whenever we use water, we contaminate it - whether we flush the toilet, take a shower, wash dishes, or do the laundry. All of this water can be easily treated at ROPEC. Other materials are more difficult to break down or remove, such as deodorants and some hair care products.
Substances like oil or paint are not meant to be treated by a municipal sewage plant. For information on how to properly dispose of hazardous waste, check out the Waste Explorer.
Ottawa's wastewater treatment plant:
- Cleans an average of 390 million litres of wastewater every day - enough to fill more than 6,000 backyard swimming pools
- Protects the environment. When the water is returned to the Ottawa River, its levels of bacteria, phosphorus and organics are far below all limits set by the plant's operating permit. The E.coli count, for example, reaches only 14 per cent of the allowed amount.
- Produces 39 dry tonnes of biosolids each day, which are used as agricultural fertilizer
The Wastewater Treatment Process
1. Coarse Screening/Pumping
Wastewater flows to the plant through enormous pipes buried deep in the ground. Upon arrival, any object bigger than a shoe gets screened out. The sewage is then pumped to ground level. It flows through the rest of the treatment processes by gravity.
2. Fine Screening/Degrit
Screens catch smaller objects like sticks and rags. Degrit tanks separate pebbles, grit and sand from the other solids that can be further treated. Screenings and grit are trucked to a landfill and buried.
3. Primary Clarification
The plant has 15 covered settling tanks. Water is slowed down to allow heavy solids to sink to the bottom, while grease and fat float to the surface. The settled solids (sludge) and floatables (scum) are removed by skimmers and sent to digesters (step 9). The remaining water still contains very fine solids and dissolved material like sugar.
In these long and deep uncovered tanks, naturally occurring bacteria break down the small particles. Air is blown into the tanks, making bubbles. This creates ideal conditions for the bacteria and keeps the solids from settling.
5. Phosphorus Removal
A solution of iron is added to the wastewater. Iron captures the phosphorus, creating a solid that can sink and be separated from the water.
6. Secondary Clarification
16 round open tanks slow the wastewater down, allowing the remaining solids and bacteria to settle as sludge. Most of the sludge is continuously pumped back to the aeration tanks, so that the bacteria can biodegrade more waste. Excess sludge is further processed (step 9).
Leaving the secondary clarifier, the water is disinfected by adding chlorine, the equivalent of strong household bleach. This kills the majority of microorganisms that have survived the treatment process.
A final chemical is added to remove excess chlorine. Now the treated water can be returned to the river.
9. Biosolids Processing
Excess sludge and scum is treated in six sealed tanks (anaerobic digesters), using other naturally occurring bacteria. These bacteria convert about half of the sludge into methane gas, and carbon dioxide. The rest goes through centrifuges, where water is removed. What is left is a nutrient-rich, soil-like material called biosolids. Farmers use it as a fertilizer.
The methane gas that has been produced in the anaerobic digesters is burned in engines and boilers, producing heat and electricity that is used to run the plant.
Cease the Grease
Download a printable version of the brochure.
Hauled liquid waste from rural restaurants can be a problem for Ottawa's wastewater treatment plant. You can be the solution.
The City's wastewater treatment plant is designed to treat sewage from various sources. To be accepted at the Robert O. Pickard Environmental Centre (ROPEC), all wastewater must meet the limits set by the Sewer Use By-law (2003-514).
Liquid waste that is brought in from rural restaurants can cause problems at ROPEC. If a grease trap is absent or not properly maintained, the oils and fats can clog the plant's piping and equipment. The grease has to be manually removed at a high cost.
Commercial hauled liquid waste is classified as 'restricted waste'. Restricted waste will not be discharged at ROPEC unless it has been approved by City staff, prior to being picked up by a licensed hauler. Restricted waste is received at ROPEC Monday to Friday from 8 a.m. to 3 p.m., excluding statutory holidays.
Rural restaurants, food trucks, caterers and other food service establishments can request an exemption from the restricted waste category - if they can provide proof of a grease trap and maintenance records. Once exempted, staff will determine if the hauled liquid waste may be mixed with domestic sewage which is accepted between 7 a.m. and midnight, seven days a week.
These don't go down the drain...
- Cooking oil
- Melted butter
- Meat fats
- Creamy sauces
This keeps grease out of your wastewater...
- Install a grease trap if you don't have one. It's a provincial law.
- Check and clean your grease trap regularly and properly.
- Recycle used oil.
- Scrape all remaining food from plates and utensils before washing them.
- Always use sink basket strainers to collect food waste.
- Train your staff.
- Used a licensed hauler
Sinks Are Not Garbage Cans - Restaurant Grease (brochure)
Download a printable version of the brochure.
Keep grease out of the sewer
Restaurants, food-service operations and establishments are major contributors to grease accumulation in our sewers, and the resulting blockages and backups. Major sources of grease are baking goods, lard, food scraps, cooking oil, shortening, butter, creamy sauces, dairy products (i.e. milkshakes), meat fats, batter and gravy.
What is a grease trap?
Grease traps and interceptors are containment units that are designed to trap grease, oil, solids and other debris. They prevent these substances from getting into the sanitary sewer systems where they can accumulate and eventually block the entire pipe.
Grease traps and inceptors need to be properly sized, installed and, most importantly, maintained!
What to do with grease?
When cleaning the grease trap or interceptor scoop out the solidified grease portion on the top and place in the grease recycling bin or garbage for disposal. Place the liquid portion in a sealable container. Used cooking oil can be recycled. Storage bins can be obtained from cooking oil recyclers, usually at no cost. There are several companies that are certified and licensed grease removal contractors.
Keeping a logbook of all cleanouts and maintenance, either by you or a contractor will help maintain a grease trap / interceptor cleaning schedule.
What you should do?
- Place screens over drains
- Wipe grease from dishes and pots
- Recycle used oil
- Train employees
- Scrape food scraps and grease into green bin or garbage
- Check grease trap often and clean often
- Don’t pour grease down drains or toilets
- Don’t use degreasers, emulsifiers or hot water to dissolve grease
- Avoid pouring grease straight into garbage dumpster
Did you know?
- Grease build-up is the main cause of restaurant sewer backups
- Restaurant sewer backup may result in immediate closure
- Grease build-up can flood basements throughout the city
- Grease trap installation and maintenance is Mandatory
- Don’t use emulsifiers, degreasers, or hot water to clean grease
- Employee education is the key to success
Why is it important to you?
Under the Ontario Building Code 350.06, grease traps are required anywhere food is cooked, processed or prepared. There are also enforceable limits in Ottawa’s Sewer Use By-law that prohibit the discharge of grease and oil over certain levels. These limits are enforceable through penalties and fines.
It is very expensive to return the sewer back to normal after a grease blockage and backup. This cost by the City can be charged back to the restaurant or food establishment. If a blockage does occur, the Public Health inspector may close the restaurant, and any restaurant upstream of the blockage, until water use can resume. This could result in an entire day or more of lost operating hours and revenue.
Grease build-up in the sewer system and treatment facility results in higher operating costs, which can result in higher sewer rates and taxes for Ottawa residents.
These don’t go down the drain:
- Cooking oil
- Meat fats
All About Sewers (activity book)
Learn more about Ottawa's sewers through fun games and puzzles in our downloadable activity book!