WC146 JanFeb 2026 - Magazine - Page 36
WASTEWATER
“Soil is a living, breathing organism. Having macroand micronutrients along with organic matter
really makes these soils long-term sustainable.”
Emerging contaminants—particularly PFAS and microplastics—are increasingly in the public eye. What does
the science show about their presence and risk in
biosolids?
PROSSER: Metals, PFAS, microplastics, pharmaceuticals—these can be present in biosolids. It’s an issue of
where they come from. Historically it was the Wild
West: everything went down the drain and would end
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WATER C AN ADA • JANUARY/ FEBRUARY 2026
up at your wastewater treatment facility. But that has
evolved. For the most part, if you have good source
control, the levels of contaminants in biosolids are
relatively low.
That’s not to say we shouldn’t continue to measure
that on a regular basis and make sure that the levels don’t
exceed concentration. But for the most part, if it’s done
well, if best management practices are followed, the
levels that you’re seeing in biosolids are relatively low.
In Maine, farmer soil was contaminated by forever
chemicals… The issue was poor source control. When
you dig into these extreme examples, something has
malfunctioned—best management practices weren’t
followed.
Does the pelletization process further contribute to
contaminant breakdown in biosolids?
MARTO: It does because of the heating process… that
gets rid of much of the E. coli. By heating the biosolids
up to 200-plus degrees Celsius before it turns into a
pellet, that makes it a third grade A fertilizer that can
be spread on any field.
WAT E R C A N A D A . N E T
Getty Images
What environmental benefits has Toronto observed
from pelletization?
MARTO: For every one truck of pellets that goes out,
four trucks of 26 per cent biosolids would go out. That
means fewer trucks on highways, reducing greenhouse
gas emissions. We’re also at 100 per cent beneficial
use… nothing goes to landfill.
VUICIC: By supplying this fertilizer that’s a recovered
product, we don’t have to produce much more synthetic fertilizer. Producing fertilizer is a very energy-intensive process… And having a product in our local
market means that we don’t have to ship fertilizers to
get them to our local agricultural community.
