DELAWARE COUNTY, OHIO
The Delaware County (Ohio) Regional Sewer District faces unique environmental challenges. Delaware County features a large amount of undeveloped land. Combined with the county’s proximity to Columbus, this has created intense demand for housing, resulting in explosive population growth and increased daily flow. The Challenge In 2012, after years of significant population growth and daily flow increase, the Tartan Fields and Scioto Reserve wastewater treatment facilities’ discharge permits were modified by the Ohio Environmental Protection Agency (EPA), requiring a new limit of 10 mg/L total inorganic nitrogen (TIN). The county faced the possibility of a significant capital investment in order to meet an 18-month compliance schedule. The Solution The county had a voluntary assessment from Ohio EPA’s Compliance Assistance Unit (CAU) completed and the assessment determined the primary goal was to evaluate nitrate levels in and after the anoxic zones to ensure appropriate denitrification in the process. The CAU installed an IQ SensorNet (IQSN) 2020 XT monitoring and control system from YSI, to monitor critical parameters in real time. The IQSN provided a modular plug-and- play system to continuously monitor ammonium, nitrate, dissolved oxygen, pH and oxidation-reduction potential (ORP) in the oxic and anoxic zones using a single networked monitoring system. With the IQSN’s simple one-cable networking design - the CAU was able to get the instrumentation up and running quickly to get the information it needed.
Objective: Meeting Discharge Limits for Total Inorganic Nitrogen
Delaware County RSD Scioto Reserve WRF Oxic Zone Daily Average Ammonium + Nitrate
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Anoxic Zone with floating mixer; TriOxmatic (dissolved oxygen), VARiON (ammonium, nitrate), and SensoLyt (pH, ORP) sensors in background
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Oxic Zone - Ammonium + Nitrate
Acknowledgements: Jon van Dommelen Ohio EPA Compliance Assistance Unit
Logged data from the 2020 XT Controller can be downloaded and analyzed. This chart shows daily average measurements simulating compliance level monitoring.
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