Statistics Canada released new wastewater data that details sewage flow numbers through municipal wastewater systems, the degree to which it is treated, and the range of populations served by treatment type.

According to the data released in late June, some 5,910 million cubic metres of sewage flowed through Canada’s municipal wastewater systems in 2017.

StatsCan staff stated in a synopsis that the national total included systems that “processed 100 cubic metres per day or more of sewage in 2017, equivalent to the volume of water that flows over Niagara Falls over a 24-day period.”

The national sewage flow remained relatively consistent from 2013 to 2017, the time period covered by the new data. The national total does not include discharges from combined sewer overflows. StatsCan notes that an additional 164 million cubic metres were discharged from combined sewer overflows in 2017.

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Quebec had the highest amount of sewage flowing through its systems with 2,172 million cubic metres of sewage, while the Yukon and P.E.I. had the lowest amount, at 4.5 and 14.2 million cubic metres, respectively.

In 2017, the total volume of untreated wastewater from combined sewer overflows and systems that provided no treatment reached 270 million cubic metres. Systems that provide no treatment discharged 106 million cubic metres of wastewater back into the environment, or just 4.4% of untreated wastewater was discharged in Canada, the new StatsCan data shows.

The StatsCan data also reveals that 1,535 million cubic metres of wastewater were discharged nationally from primary treatment systems, removing material that will either float or readily settle out by gravity.

National secondary treatment involving the removal of soluble organic matter that escaped primary treatment and the removal of suspended solids was slightly higher at 1,544 million cubic metres.

Tertiary treatment, which can remove remaining inorganic compounds and substances such as nitrogen and phosphorus, served the most Canadians nationwide, totalling 9.8 million residents. Secondary treatment served 7.7 million Canadians, while primary treatment served 4.8 million.

In 2017, just over 30 million people were served by municipal wastewater systems that have daily flows that process 100 cubic metres per day or more.


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