Severn Trent Services Provides World's Largest Fixed-Film Denitrification System for Baltimore Wastewater Treatment Plant

TETRA® Denite® denitrification system will dramatically reduce the Patapsco Wastewater Treatment Plant's nutrient discharges into the Chesapeake Bay.

FORT WASHINGTON, Pa. - Severn Trent Services has been awarded a contract to supply their TETRA® Denite® denitrification system for use at the Baltimore City Department of Public Works' Patapsco Wastewater Treatment Plant. The tertiary treatment system will help reduce the plant's discharge of total nitrogen (TN) by more than 80 percent and total phosphorous (TP) by more than 90 percent, significantly reducing nutrients discharged to the Patapsco River and, ultimately, the Chesapeake Bay. The Patapsco Wastewater Treatment Plant is undergoing upgrades and expansion over the next two years. Once completed, it will be the largest installed fixed-film denitrification system in the world.

The contract for the denitrification system was awarded by Fru-Con Construction Corporation, in Woodbridge, Va., the project's general contractor. Rummel, Klepper & Kahl, LLP of Baltimore is the consulting engineer for the plant expansion and selected the TETRA Denite system for use at the Patapsco facility.

The construction project, which is scheduled for completion in 2013, is designed to treat an average flow rate of 81 million gallons per day (mgd) and a maximum of 150 mgd. The TETRA Denite denitrification system will enable the Patapsco facility to reduce nitrate-nitrogen (NO3-N) to 0.5 mg/l and total suspended solids (TSS) to 5 mg/l at the plant's average flow rate. Severn Trent Services has provided a process performance guarantee for the effluent parameters of the Denite system. The Denite system is the only fixed-film denitrification system that has proven it can reduce NO3-N to 0.5 mg/l or less at average daily flow rates.

The TETRA Denite system is an economical solution for the removal of NO3-N and TSS in a single treatment step. Denite is a fixed-film biological denitrification process that also serves as a deep bed filtration system capable of removing suspended solids to virtually any final effluent level requirement. The system integrates well with other plant treatment processes to provide superior TN and TP removal.

According to Joe Bonazza, Filtration Business Unit director for Severn Trent Services, "The Chesapeake Bay is the nation's largest estuary and has long been the focus of intensive government-sponsored restoration efforts, including strategies to reduce nitrogen and phosphorous discharges. Fixed-film biological denitrification has proven to be highly effective in helping wastewater treatment facilities meet low NO3-N, TSS and TN limits."

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 analytical services group is the United Kingdom's leading environmental testing organization, and our international operating services business provides worldwide contract operation and support for all aspects of water and wastewater utility operational development and business transformation. 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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