City tries to get the most bang for its (sewage) buck

The City of Winnipeg is exploring new ways to reuse its treated sewage sludge.

An expression of interest seeks feedback on the best options and technology available to recycle biosolids, a byproduct of the sewage treatment process. The document notes the treated sludge can be composted, used like a fertilizer, or even be transformed to produce energy.

A massive $3-billion upgrade to the city’s North End sewage treatment plant will add new biosolids facilities that improve the end byproduct, which means the city could soon have more options to reuse it, said Cynthia Wiebe, Winnipeg water and waste’s manager of engineering services.

“The key difference is that there are no pathogens in the (biosolids from the new facility),” said Wiebe.

The treatment plant currently produces Class B biosolids, which contain more pathogens (germs) that can cause disease.

The new facility will produce Class A biosolids, which are easier to reuse because they meet strict limits for pathogens and trace metals, the document notes.

That makes the byproduct suitable “for unrestricted use, including on public lands, agriculture and landscaping,” the expression of interest says.

When used like a fertilizer, that would require fewer limits and regulations, said Wiebe.

Meanwhile, the material could also be used as an energy source.

Vancouver dries out some of its biosolids to convert into fuel.

“One thing we would try to find out from this expression of interest is what technologies are there. We do know that when you digest the organic matter, it creates a gas. We’re trying to see what the possibilities are,” said Wiebe.

She said the sewage sludge treatment process at the updated biosolids facilities will act sort of like a slow cooker, using heat to kill off potentially harmful elements. What’s left behind would still offer a nutrient-rich compost.

The City of Winnipeg has studied how best to reuse biosolids for years.

In 2024, 60 per cent of Winnipeg’s Class B biosolids were blended with street sweepings and wood chips to create a top cover for the former Summit landfill, while about 40 per cent were spread on agricultural land with strict conditions and precautions.

The new biosolids facility is expected to produce about 60,000 to 65,000 wet tonnes of biosolids each year.

Wiebe said there could be further options to improve soil in the future, with the higher quality material.

“We’re taking nutrients from (food grown on) the land, we eat them and we’re processing them and then we’re putting the nutrients back into the land,” said Wiebe.

She noted one Washington process to reuse biosolids is often referred to as “the poop loop.”

“It really is about that circular economy and making sure we’re not wasting it. That really benefits the environment… because we need these nutrients. We know we need them to grow (things) and we have a ready source of them,” said Wiebe.

It’s not yet clear if the city would be able to sell or give away any converted biosolids, such as potential fertilizers, she said.

Coun. Ross Eadie, chairman of city council’s water and waste committee, said the city hopes to reuse as much waste as possible, keeping it out of the landfill.

Eadie (Mynarski) said he suspects using treated sewage to produce energy would be too expensive to pursue but stressed existing forms of reusing biosolids are already producing benefits.

“At (the former Summit landfill), it’s helping the prairie grasses to grow, which reduces the methane that’s released,” he said. “It’s about reusing what’s already in the sewage.”

Coun. Brian Mayes, a member of the water and waste committee who has worked on keeping biosolids out of the landfill for years, said he’s encouraged to see the city reuse the material in every way feasible.

“We’re spending billions on that North End plant (upgrade). We’re going to have this as a byproduct so the more we can do with it to recover some of the costs or to help with the environment, the better,” said Mayes (St. Vital).

joyanne.pursaga@freepress.mb.ca

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