Environmental Science & Engineering - www.esemag.com - September 2004
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Multi-stage scrubber system eliminates pumping station odours
With a population of well
over 40,000, Aurora,
Ontario is one of the
fastest growing communities
in Canada. The Aurora Sanitary
Sewage Pumping station accepts
sewage from the town, and also serves
as a collection point for septage that is
trucked to the facility by numerous private
waste haulers.
Private homes, condominiums, a
day care facility, and a golf course
have been constructed on residential
and commercial lands located very
close to the facility. As the population
of the area grew and the sewage flow
to the station increased, odours emitted
from the facility became a nuisance.
The Regional Municipality of York
retained Conestoga-Rovers & Associates
(CRA) to perform air sampling, identify
the odour causing compounds,
assess regulatory requirements, and
design an odour control facility.
Asco Construction Ltd. began construction
of the odour control facility
in the fall of 2002. The scrubber system
was installed and put into complete
operation by the spring of 2003.
The system includes Duall Division
model NH exhaust fans, ducting,
Fybroc 1500 Series fiberglass recycle
pumps, and chemical supply tanks
along with the scrubber.
The Duall model PT510 multi stage
scrubber system is designed to treat
22,363 cfm of process exhaust air containing
ammonia and hydrogen sulfide
odours. It is designed to remove 99%
of ammonia at minimum inlet concentrations
of 20 parts per million by volume
(ppmv).
The 96” diameter first stage scrubber
utilizes sulfuric acid addition to
achieve the ammonia removal. The 96”
diameter second stage scrubber is
designed to remove more than 99% of
the hydrogen sulfide odours at minimum
inlet concentrations of 60 ppmv.
This is a relatively high concentration
of hydrogen sulfide, due primarily to
the frequent inflow of septage collected
at the station from private waste
haulers. The second stage utilizes sodium
hydroxide and sodium hypochlorite
addition to achieve the required
hydrogen sulfide removal.
The scrubbers are constructed of
corrosion resistant, High Strength
Type II PVC conforming to ASTM D
1784 standards. The system is expected
to operate at approximately 6” of
positive air pressure. Both scrubbers
are constructed for nearly 20” of positive
operating air pressure, providing a
safety factor in excess of 3. The system
is also designed in accordance with
Universal Building Code seismic zone
2A requirements with a safety factor in
excess of eight.
Duall Division is represented in
Ontario by Metcon Sales &
Engineering Ltd.
Contact e-mail: metcon@metconeng.com.
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