The City of Montreal is replacing the aging incinerators at its wastewater treatment plant, as it undergoes other upgrades that will allow it to lay claim to the largest ozonation unit in the world.
The Jean-R. Marcotte Wastewater Treatment Plant is the third largest of its kind in the world and located in Point aux Trembles on the eastern tip of Montreal Island. Built in 1984, some 350 workers help the treatment plant, the city’s only wastewater system, to process up to 7.6 million m3 of water each day.
In the December 2022 budget, the city earmarked $682 million over 10 years to replace the plant’s incinerators. Local officials estimate that the incinerators account for some 30% of the greenhouse gas emissions from city-owned buildings.
Also in December, city officials reserved $461 million for the ozonation project. The new equipment and building will be built directly next to the wastewater treatment plant.
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The city already uses ozone to treat its drinking water.
Originally set to be completed by 2018, the ozonation unit hit a substantial design snag when receiving canals needed to be reconfigured. Despite the decision being made in 2008, Montreal officials believe ozonation is still the most efficient way to disinfect the water and eliminate viruses, bacteria and pharmaceutical residue before effluent is discharged into the St. Lawrence River, preserving the health of aquatic life. The city estimates that the new system will remove up to 99% of bacteria and viruses and up to 80% of emerging contaminants of concern.
Montreal was one of the last major cities in North America to start treating its wastewater. For decades it had only removed solids and some particulates with chemical coagulants.
In December, Montreal city council also awarded a contract to Filtrum Construction for the upgrades of the plant’s bar screens, compactors and conveyors. It also approved a transfer agreement with Pomerleau Inc. and Groupe LAR Inc. in relation to hydraulic evacuation structures for the disinfection project.
In order to conduct the upgrades, the treatment capacity of the plant will be reduced during two six-month periods between November 2022 and April 2023, as well as between November 2023 and April 2024.