view . fall 2012
5
Have you ever thought about what happens after someone
flushes unused medications down the toilet?
Rajesh Seth has
done just that.
A professor in civil and environmental engineering,
Dr. Seth studies levels of potentially harmful chemicals including
pharmaceuticals and personal care products (PPCPs) being found
in treated wastewater, and more
importantly, what to do about them.
“I don’t want to set off alarm
bells, but these are being found in low
concentrations,” he says. “There is
concern about them being frequently
detected and what their possible effects
might be.”
At least 80 PPCPs including
antibiotics, antidepressants, and blood
lipid regulators have been identified in
outflows from wastewater treatment
plants worldwide, according to a 2007
Environment Canada report. Closer to
home, Seth co-authored a study that
reported 14 of 51 targeted chemicals
were consistently found in samples of discharge water from a local
sewage treatment plant which empties into the Detroit River.
Part of the problem is people’s indifference to disposing of a
variety of products, according to Chris Manzon BASc ’90, MASc ’00,
plant manager at the Little River Pollution Control plant where
Seth’s team is conducting its research.
“The toilet is not a garbage can,” says Manzon. “These
chemicals go somewhere when you flush them.”
There is emerging concern in the scientific community about
endocrine-disrupting chemicals found in PPCPs and their potential
to harm human hormonal systems.
Seth is studying the use of ozone to remove them from
wastewater after it’s treated. It’s a method already used to treat
drinking water at the A.H. Weeks Water Treatment Plant, which
distributes up to 349 million litres of water to Windsor residents
each day. Seth believes drinking water would be further protected
if there were better methods of treating wastewater before it gets
dumped into the ecosystem and makes its way back to drinking
water intakes that treatment plants rely on.
“It just made more sense to remove those chemicals at the
source,” he says.
Manzon says the plant’s conventional sludge-activated system—
which relies on microbial processes and UV light to eliminate
contaminants—removes about 98 per cent of such harmful
materials as human waste, nutrients and pathogens from the 45
million litres of wastewater it treats
every day, but isn’t equipped to deal
with chemicals found in PPCPs.
“We do a good job of getting most
of the stuff out, but this technology is
100 years old,” he explains.
At the plant, Seth and his team
of graduate students set up a mobile
research station. Pure oxygen runs
through a generator to produce
ozone, a pale blue gas made up of
three oxygen atoms that smells like
chlorine. That ozone is diffused in
a bubbling column of water already
treated by the plant. Another column
contains the un-ozonated water, and
researchers compare the two.
Master’s student Saileshkumar Singh said the method is
removing chemicals at a rate of about 80 per cent.
“It’s been very effective for both disinfection and for removal of
contaminants of concern,” he says.
The process, however, does create some by-products, so
fellow student Mike Reaume is working on a follow-up biological
treatment to address them. If they can be overcome, Singh says he
hopes ozone will be widely implemented as a method of treating
wastewater: “I think Canada is a country that’s been a world leader
in wastewater treatment and at implementing new processes.”
For the time being, Manzon is happy to have the researchers
in his plant testing its effectiveness. “We really don’t know what
the long term effect of these chemicals might be,” he says. “The
University has had a long history of doing pilot studies with us here
and at other facilities. When they have something they’d like to
try, we like to be here for them. Down the road, it may be of some
benefit to the facility.”
n
v
REDUCING THE H
2
O
CHEMICAL EQUATION
Drugs in the water
“The toilet is not a garbage
can, These chemicals go
somewhere when you flush
them... We do a good job of
getting most of the stuff
out, but this technology is
100 years old.”
Chris Manzon
BASc ’90, MASc ’00
RESEARCH
BY STEPHEN FIELDS
