Following water from flush to finish
Treatment plant employs many methods to clean sewer water
At the end of all those loads of laundry and hot showers and trips to the bathroom sits the Fox River Water Pollution Control Center.
The facility, more commonly known as Brookfield’s wastewater treatment plant, occupies a little more than half of a 30-acre site at the end of Enterprise Drive. Serving the portion of the city west of the subcontinental divide and six other communities, the pollution control center treats nearly 13 million gallons of wastewater a day.
That’s 13 million gallons of water from showers, washing machines, sinks and toilets that comes through the facility to be treated by a series of physical, chemical and biological processes before being discharged into the Fox River.
Wastewater from the east side of the subcontinental divide travels to the Milwaukee Metropolitan Sewerage District for treatment.
So how does the Fox River Water Pollution Control Center work? Just follow along with plant manager Ron Eifler to find out.
Capacity has increased
Eifler starts the tour — on this windy September morning he’s guiding a reporter and Seventh District Alderwoman Renee Lowerr, a member of the city’s Water and Sewer Board — with a bit of history. Brookfield’s first wastewater treatment facility was built in 1961 on Riverview Drive, near where the city’s Highway Department now sits. The facility served 34 connections and could treat a peak flow of 1 million gallons of wastewater a day.
A bigger facility was built on the current site in 1974. The Environmental Protection Agency, the Wisconsin Department of Natural Resources and the Southeastern Wisconsin Regional Planning Commission designated the center — then with a peak flow of 5 million gallons a day — as a regional treatment plant for the Upper Illinois Fox River watershed.
Expansion in Brookfield and the surrounding area led to further expansion at the water pollution control center, which in 1985 grew to a peak capacity of 10 million gallons a day.
The most recent expansion concluded in 2000, and the plant now can treat up to 50 million gallons a day, although the typical flow is about 12.5 million gallons a day, Eifler says.
About half that wastewater comes from Brookfield, with the city of Pewaukee and the town of Pewaukee the next two largest contributors.
Best to be upwind
The wastewater starts its voyage at the influent pumping station, where six huge pumps — operating with a capacity of 38,000 gallons a minute — move the wastewater to the bar screens and grit chamber, which filter out debris like rags, stones and sand.
At this stop, the water is pumped to the highest point in the plant so it flows through the rest of the process using gravity, minimizing costs, Eifler says.
The wastewater then moves to the primary clarifiers, where suspended solids settle to the bottom of the tanks and floating debris is skimmed from the surface. Since this step in the process is one you don’t want to be downwind of, the primary clarifiers are connected to the plant’s mechanical odor control system.
If flows are greater than 31 million gallons a day — or 21,000 gallons per minute — the excess flow is automatically diverted to a set of alternate clarifiers for treatment. Eifler says the plant used these clarifiers during the June storms, when the plant hit a peak flow of 68 million gallons a day.
“We had all the doors open — shall we say — that we could,” he says.
Ready for reuse
During a normal, non-100-year-storm day, the wastewater moves from the primary clarifiers to the aeration tanks, where millions of aerobic microorganisms — excited by an injection of oxygen — ingest the organic matter.
“They just gobble that stuff up,” Eifler says.
The wastewater then flows through the final clarifiers, where the microorganisms settle to the bottom of the tank. The microorganisms are sent back to aeration tanks to help remove organic matter, and the wastewater moves to the deep-bed sand filters, which further remove microorganisms.
The wastewater from the deep-bed sand filters is then disinfected with an injection of chlorine in the chlorine contact tank. Sulfur dioxide is introduced to neutralize the chlorine in the water, which is then sent to the post-aeration tank.
In the post-aeration tank, oxygen is again added to the water to make up for that lost during the neutralization of the chlorine. Finally, the treated water is released into the Fox River.
The leftover biomass from the process is stored in two 2 million-gallon tanks. The sludge is spread on nearby farmlands. The city recently started a pilot program with MMSD to use the sludge to produce Milorganite, an organic fertilizer.
Alan Hamari can be reached at (262) 446-6601.
BY THE NUMBERS
entities served by the Fox River Water Pollution Control Center: city of Brookfield, town of Brookfield, Lake Pewaukee Sanitary District, Menomonee Falls, New Berlin, city of Pewaukee, village of Pewaukee
employees at the wastewater treatment facility
estimated number of manholes in the city
average annual electric bill costs for the Fox River Water Pollution Control Center
cost of the latest renovation and expansion at the facility; the project was completed in 2000 after 42 months
AT A GLANCE
WHAT: Fox River Water Pollution Control Center
WHERE: 21224 Enterprise Drive
WHO: To set up a tour, call plant manager Ron Eifler at (262) 782-0199.
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