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Fox River Water Pollution Control Center –
Brookfield, WI
This project
included a comprehensive evaluation and design of
potential odor sources throughout the plant. The major
odor-generating processes at the plant were the influent
pump station, the aerated grit tank and grit storage
area, the primary clarifier weir areas, and the belt
filter press operation for dewatering anaerobically
digested biosolids. All of these processes were
expanded as part of the treatment plant project. To
address the known and anticipated odor concerns at the
plant, a comprehensive odor control program was included
in the overall design of the plant improvements.
Several unique features of the odor control systems
include hooded enclosures for the grit dumpster and belt
filter presses, primary clarifier weir covers, and
“channel seals” to control air flow pressure and air
flow within the covered raw wastewater channels.
One new 16,000-cfm
chemical scrubber (caustic and hypochlorite) was added
in the preliminary treatment building to remove hydrogen
sulfide and other reduced sulfur compounds in the
headworks area and from the primary clarifier weirs
(covered).
In the biosolids
processing building (anaerobically digested biosolids),
an existing single-stage chemical scrubber (two units)
was converted to a two-stage scrubber for ammonia
removal using sulfuric acid in the first stage and
hydrogen sulfide removal using caustic/hypochlorite in
the second stage. Air is vented from the belt presses
at approximately 12,000 cfm to the two-stage scrubber.
Anaerobically digested
supernatant is stored in holding tanks before being bled
back into the wastewater treatment flow. These
supernatant tanks were covered and provisions for
exhausting the headspace with the existing aeration tank
blowers was provided. This air can be directed to the
aeration tank diffusers at the bottom of the basins for
oxidation and control of odors from these storage tanks.
Air sampling in and
around the various treatment plant facilities have
indicated a significant reduction in odors when the odor
control systems are in operation.
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