Back River Wastewater Treatment Plant upgrade approved in Baltimore, US

The Board of Estimates of the City of Baltimore has approved a $263.5m contract for the first phase of construction of an enhanced nutrient removal facility (ENR) at the Back River Wastewater Treatment Plant.

The contract has been awarded to Archer Western Contractors, a company involved in construction for the water, wastewater and transportation sectors.

It involves the construction of a 300 million gallon/day pumping station, 52 biological filters and chemical feed facilities. There will also be changes to two existing activated plants and construction of supporting plant infrastructure including underground utilities, roadways, communications and plant process control systems.

The project is part of the Chesapeake Bay Restoration Program mandated by the Maryland Department of the Environment. It aims to reduce nitrogen and phosphorus nutrients dumped into the Bay; two elements that are generally found in wastewater influent at treatment plants. At Back River, around 35,000lb of nitrogen and 6,000lb of phosphorus enter every day in the influent wastewater.

Baltimore Public Works director Alfred Foxx said: "When completed, it will dramatically reduce the nutrients that contribute to algae blooms which reduce the oxygen content in the water and cause fish kills."

Water treatment plants in the State of Maryland started nutrient reduction in the late 1990s, aiming to eliminate around 70% of incoming nitrogen using biological nutrient removal technology.

Under the improvements, nitrogen levels will be further reduced to achieve an over 90% total reduction. Chemical treatment at Back River has already resulted in eliminating 90% of phosphorus from treated water.

Work on the Back River ENR projects is scheduled to be completed by December 2016.

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Image: At Back River plant, about 35,000lb of nitrogen and 6,000lb of phosphorus enter every day in the influent wastewater. Photo: courtesy of antpkr.