WC141 MarApr 2025 - Magazine - Page 20
WASTEWATER
Commonly referred to as “forever chemicals,” PFAS are a
group of synthetic chemicals that have been used in industry and
consumer products since the 1940s. They are found in many
everyday items, including firefighting foams, textiles, personal care
products, cosmetics, non-stick cookware, food packaging materials,
and water- and grease-resistant coatings.
When it comes to drinking water, monitoring has shown
that potential PFAS exposure is relatively low, and effective
treatment technologies are available—though costly. The U.S.
Environmental Protection Agency (EPA) has set a Maximum
Allowable Concentration (MAC) for PFOA and PFOS in drinking
water, which applies to all utilities in the U.S. In Canada, Health
Canada has established an “Objective Value” of 30 ng/L as a
cumulative measurement of 25 specific PFAS compounds within
the Canadian Drinking Water Guidelines. As an objective value,
it allows for greater flexibility in adjusting standards as new data
emerges. Each province and territory can then adapt this value to
set their own regulations. Utilities must consider source protection,
laboratory sampling and testing requirements, and potential
treatment technologies. Meanwhile, Health Canada continues
to monitor ongoing research and is expected to publish a healthbased MAC in the future.
Addressing PFAS in municipal wastewater is even more
complex, particularly in sewage sludge and biosolids (the residual
material left after treatment). Treating PFAS in solids and semi-
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solids is significantly more challenging than treating clear
source water. It is important to note that wastewater treatment
facilities (WWTFs) do not produce PFAS; rather, they are
“passive receivers,” collecting PFAS from various sources,
including industrial sites (factories, manufacturing plants),
commercial operations (dry cleaners, car washes), and residential
sources (laundering PFAS-treated fabrics, improper disposal of
chemicals). Of particular concern is leachate from landfill sites.
The Government of Canada has been regulating PFAS since
2008. The Canadian Food Inspection Agency has adopted
an interim standard of less than 50 parts per billion (ppb) of
PFOS as an indicator of PFAS contamination in commercial
fertilizers derived from biosolids. Environmental monitoring
programs have shown that 90 per cent of Canadian-produced
biosolids contain PFOS concentrations below this threshold.
The concentration of PFOA and PFOS in biosolids has been
found to range from below detection limits to 23 and 25 ppb
(dry weight), respectively. It is expected that PFAS levels in
biosolids will continue to decline due to increasing regulations
and restrictions on PFAS production. Notably, consumers are
exposed to far higher PFAS levels through everyday products
than through biosolids application.
The quality of municipal wastewater biosolids reflects
what a community discharges into its drains and sewers.
Reports of highly contaminated sites typically come from
WAT E R C A N A D A . N E T
Ontraio.ca
“The potential accumulation of PFAS in wastewater systems is
far greater as they collect e昀툀uent from industrial sites…”
