We know that wastewater affects the health of rivers and watercourses. So we went to the source, that is to say behind the scenes of the Jean-R.-Marcotte wastewater treatment plant, which treats almost all of Montreal's wastewater! We came away impressed by the workload that it represents and by the ingenuity of the process (which will be significantly improved once the water ozonation step is added) and for my part, I must say the smell that comes from it!
The Jean-R wastewater treatment plant. Marcotte: a huge factory
Every day, the Jean-R.-Marcotte treatment plant treats approximately 5 million cubic meters of wastewater before returning it to the St. Lawrence River. That's half of the wastewater treated in Quebec! It receives all wastewater from Sainte-Anne-de-Bellevue to Riviere-des-Prairies—Pointe-aux-Trembles, where it is located. There is indeed a small wastewater treatment plant on Notre-Dame Island in Montreal, but its size has nothing to do with the Jean-R.-Marcotte station.

How is wastewater treated?
We put on our masks, helmets and protective gloves to follow the journey of transforming wastewater into treated water.
1. Passage to the pumping station
Wastewater arrives at the treatment plant underground. They are therefore brought up to the surface at the pumping station in enormous suction wells, some of which are up to 43 meters deep! There are two for the northern waters of the island, and two others for the southern waters. The water is then sent into huge pipes. Everything works thanks to 17 pumps and 17 motors, as well as an energy center containing generators in the event of a power outage. Indeed, a cessation of operations is inconceivable!

2. Chemical treatment
So far, my fine nose and I are doing well. But things get bad near the intake canals, where the water goes after its visit to the pumping station. It must be said that so far, no treatment has taken place. This is about to change: a coagulant is injected, which will reduce phosphates in the water and increase the efficiency of settling, a subsequent step.
3. Screening
You have the power to mitigate the impacts of wastewater on the St. Lawrence River by avoiding using a waste disposal and flushing down the toilet: - Hair; – Tampons, wipes and other sanitary products; – Leftover cooking oils, sauces, vinaigrettes, in short any food product! You can put them in a container in the freezer, then in the compost; – Orange cones! |
About the author
Sophie Lachance
Press filters dehydrate the sludge, which then takes on the beautiful little name “cake” (yum!). The cakes will either be transformed into pellets for agricultural purposes, or be cremated, the ashes of which will be buried.