Water Connections: Nutrient Removal in Chesapeake Bay

An upgrade of the WSSC’s Seneca Wastewater Treatment Plant in suburban Washington, D.C., included the addition of a new denitrification process to help achieve enhanced nutrient removal (ENR) requirements.

The Seneca Wastewater Treatment Plant upgrade included the addition of a new denitrification process.
The Seneca Wastewater Treatment Plant upgrade included the addition of a new denitrification process.

The Washington Suburban Sanitary Commission (WSSC), which is in close proximity to Chesapeake Bay, recently received new discharge requirements for allowable nitrate in its treated effluent. To meet that, the WSSC Seneca Wastewater Treatment Plant underwent a facility upgrade that included the addition of a new denitrification process to help achieve enhanced nutrient removal (ENR), reducing total nitrogen (TN) in treated effluent to less than 4.0 mg N/L and minimizing operating costs.

In order to meet the stringent treatment requirements, the Seneca team needed monitoring technology that could provide accurate, real-time data. Following a side-by-side evaluation, IQ SensorNet NitraVis© UV-Vis sensors from YSI, a Xylem brand, were selected. Using a feedback control strategy with a nitrate set point of 1.8 to 2.0 mg N/L, the nitrate sensors were placed at the downstream end of the anoxic zone. Treatment performance varied throughout the day but stayed within target levels, with effluent TN averaging 1.98 mg N/L over a recent 12-month period.

The IQ SensorNet system satisfied all the measurement performance requirements and includes advantages such as UltraClean™ ultrasonic cleaning technology, stackable modules and a single-cable design. WSSC operators are very pleased with the performance and the IQ SensorNet has enabled them to optimize their process, reduce costs and implement control protocols based on real-time data. Achieving their nutrient numbers has never been easier. WW

YSI, a Xylem brand, is exhibiting at WEFTEC.19, booth 1248. To learn more, visit www.xylem.com.

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