Feb 11, 2014

Baltimore to House World’s Largest Deep Bed Denitrification System

The project's design consists of 52 filters

Severn Trent Services Tetra Denite denitrification filter Baltimore Back River

Severn Trent Services was awarded a contract from Archer Western Contractors LLC to provide its Tetra Denite denitrification filter technology to the Back River Wastewater Treatment Plant (WWTP) in Baltimore. The Tetra Denite fixed-film biological denitrification process will be used to reduce high levels of nutrients discharged into the Chesapeake Bay from the Back River WWTP. Upon completion, the installation will be the largest fixed-film denitrification system in the world.

The project is the second of two large project bids won for Denite deep bed gravity filters in the Chesapeake Bay area, the first being the Patapsco WWTP, which currently ranks as the largest in the world.

The $24-million project’s design will consist of 52 filters — four sets of thirteen 11-ft, 8-in.-by-100-ft filters. Each set will operate independently of the others with its own controls and operation programming. All 13 systems will share the same backwash and chemical feed system.

The filters were designed to operate independently due to varying flows, allowing the filter sets to be backwashed at once. This design eliminates down time for backwashing and provides greater operational flexibility in meeting stringent Total Maximum Daily Load limits set forth by the Maryland Department of Environment and the U.S. Environmental Protection Agency. The new facility will handle the plant’s permitted flow of 180 million gal per day. The design engineer for the Back River WWTP project is Whitman, Requardt and Associates LLP of Baltimore.

After project completion, Back River WWTP’s effluent quality will be less than 5mg/L total suspended solids, less than 1 mg/L nitrate-nitrogen, less than 4 mg/L total nitrogen and less than 10 mg/L chemical biological oxygen demand.