Canstar Community News - ONLINE EDITION
How the city’s sewage treatment works
Back in the mid 1930s, when Winnipeg’s citizens became concerned about untreated sewage polluting the city’s rivers, the city began building a treatment plant.
Winnipeg thus became the first Canadian city with a population of over 100,000 to build such a thing. It was completed in 1937 and since then has been expanded and upgraded to become the North End Water Pollution Control Centre (NEWPCC).
There are three centres in Winnipeg, although the NEWPCC handles between 60 to 70 per cent of the city’s waste water including that from St. Boniface, Transcona, all of the Kildonans and a part of St. James.
The West End centre (WEWPCC) and the South End centre (SEWPCC) handle the remaining 30 to 40 per cent.
A huge system of underground sewers (2,400 kilometers-plus) collects waste water from homes and buildings and delivers it to these control centres. The overall mission is to treat this sewage prior to releasing it into the city’s rivers.
Treated water is 90 to 9 per cent free of inorganic material, such as sand and gravel and other waste, when released it into the rivers. The complete process means water takes about seven hours to pass through the plant.
As organic materials in waste water break down and decompose, screens separate the larger items that pass through, such as sticks, rags, sand and gravel, leaving only the sludge or organic materials. The larger items are taken to the landfills while the organic material is aerated. The smelly gases are vented into the atmosphere through the gigantic stacks you see from Main Street near Chief Peguis Trail in behind the plant. These stacks are over 150 feet tall.
Primary treatment eliminates about 50 per cent of the solids and about 30 per cent of the organic pollutants from the waste water. This is done in large tanks called primary clarifiers.
After settling, solids are collected using scrapers and pumped into another area for additional treatment. The secondary treatment removes the remaining organic matter. The settled sewage flows into oxygen reactor tanks where it is vigorously mixed with oxygen which speeds up the process of decomposition and separation.
The sewage is then directed to the final clarification tanks and here the bacteria laden sludge settles to the bottom of the tanks and the remaining water can be released into the rivers. Since the South End and the West End plants do not have digesters, all of their sludge is trucked over to the NEWPCC for processing.
This article only scratches the surface of the complexities of these operations and I would encourage you to go to the city’s web site if you want all of the details. I found it at http://winnipeg.ca/waterandwaste/sewage/
Rick Sparling is a community correspondent for North Kildonan. Email him at firstname.lastname@example.org
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