WC128 JanFeb2023 - Magazine - Page 23
Soil testing: Wikimedia, Thermal treatment: Getty Images
L to R: Testing for human pathogens in cereal crops
after the application of biosolids. With growing concerns with PFAS, USEPA is predicting that more and
more biosolids will be thermally treated rather than
sending directly to land application in the future.
wastewater treatment processes or biosolids facilities
do not themselves utilize PFAS chemicals. Generally
speaking, PFAS in biosolids are a concern in situations where collection systems receive sewage from
industries that manufacture PFAS or the waste from
firefighting and military operations.
Putting biosolids to the test
To address this issue, the U.S. Department of Environment, Great Lakes, and Energy (EGLE) in Michigan initiated an Industrial Pretreatment Program
(IPP), with the goal of protecting, preserving, and
improving Michigan’s surface water quality through
the implementation of Federal and State rules designed to limit pollution from industrial discharges to
publicly owned wastewater treatment facilities.6
Treated biosolid samples from 42 facilities were
WAT E R C A N A D A . N E T
found to have an average PFOS concentration of
184 /kg, while the median concentration was 13
/kg.7 A total of seven final treated solids samples
from six wastewater treatment plants (WWTPs)
were above the 150 /kg threshold that EGLE had
selected for characterizing biosolids as “industrially
impacted.”
As WWTPs with high PFOS concentrations are
identified and source reductions are implemented,
it is expected that lower concentrations in solids
on average will be observed in Michigan WWTPs
moving forward. For example, by removing the seven
industrially impacted samples, the recalculated
average biosolids concentration lowers to 18 from
184 /kg, and the median lowers to 11 from 13 /kg.
Fortunately, PFOA and PFOS, the most concerning and most-researched PFAS, have been largely
WATER C AN ADA • JANUARY/ FEBRUARY 2023
23
