Severn Trent Services to Provide World's Largest Fixed-Film Denitrification System

Baltimore, Md., TETRA® Denite® installation will be the largest deep bed denitrification project ever.

FORT WASHINGTON, Pa., USA – Severn Trent Services, a leading global supplier of water and wastewater treatment solutions, 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, Md. 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 very 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 unique design will consist of 52 filters — four sets of 13, 11'- 8" x 100'- 0" filters (3.6m X 30.5m). 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 gallons per day (818,296 cubic meters 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 1.0 mg/l Nitrate-Nitrogen, less than 4.0 mg/l Total Nitrogen and less than 10 mg/l Chemical Biological Oxygen Demand.

"Back River WWTP plays an important role in the success of the Chesapeake Bay Restoration Program by providing efficient, reliable wastewater systems to enhance and sustain a healthy quality of life for every citizen in the region. The TETRA Denite process is not new to the program. In recent years, the technology has helped dramatically improve wastewater quality at another treatment plant in the Chesapeake Bay area, helping the plant meet the stringent Class IA effluent discharge standards through the simultaneous removal of TN, TP and SS," said Severn Trent Services' project manager of the contract Ed Kuchtjak. "TETRA Denite with deep bed gravity filters was the only biological filter technology considered for this project because of its 100% proven track record and experience."

"We look forward to working on this exciting project. Establishing a strong business relationship and delivering state-of-the-art technology to the City of Baltimore Bureau of Water and Wastewater over the last 20 years are key parts of our strategy to address our customers' unique water issues," said Marwan Nesicolaci, vice president of global sales and marketing at Severn Trent Services. "With more than 40 years of experience, our biological filter technology is recognized by our customers to deliver advanced wastewater treatment plant effluent that is safe and cost effective."

About Severn Trent Services

Severn Trent Services ( with global headquarters in Fort Washington, Pa., USA, is a leading supplier of water and wastewater solutions. The company's broad range of products and services is concentrated around disinfection, instrumentation and filtration technologies and contract operating services. Our operating services business provides contract management, operations support and systems improvements for utility, industrial and commercial water and wastewater customers in the United States, United Kingdom, Ireland and Italy. Severn Trent Services is a member of the Severn Trent Plc (London: SVT.L) group of companies. Severn Trent is a FTSE 100 company.


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