The City of Montreal will install an ozonization system at its Jean-R. Marcotte wastewater treatment plant in Rivière-des-Prairies.
This project will be the the world's largest waste water treatment plant to use ozone to clean water.
The city says ozone does a better job of reducing the risk of water-borne viruses and bacteria and cleansing traces of cosmetic and pharmaceutical products and industrial waste.
For example, the city says ozonization is 99 per cent effective at removing fecal coliform and enterococcus bacteria.
The city already uses ozone to treat its drinking water.
Ozone treatment also does not require chemical additives to be mixed with water.
The plant treats wastewater before it is returned to the St. Lawrence River to reduce contamination.
It treats 2.5 million cubic metres of water daily, the equivalent of the volume of the Olympic Stadium.
Right now the city uses chemical additives to treat water.
The city says it has already completed feasibility studies and it will issue a call for tenders to install the ozonization equipment next month.
The system is expected to be running by 2018.
The city estimates the total cost for the project to be $98.5 million for installation, and $9 million annually in operating costs.
The provincial and federal governments will cover 85 per cent of the cost as part of a joint infrastructure program.