Increased levels of nitrogen in lakes, streams and other bodies of water can lead to algae growth that harms wildlife and limits recreational activities. When the town of Newmarket, New Hampshire, discovered that its wastewater effluent contained high levels of nitrogen, it built a new nitrogen-removal facility and deployed the IQ SensorNet system from YSI, a Xylem brand, to continuously monitor nitrogen levels, optimize processes and lower costs.
The town of Newmarket is located on the banks of the Lamprey River, which feeds into a 6000-acre (24-square kilometer) tidal estuary called the Great Bay, home to a diverse and protected ecosystem.
In 2009, a New Hampshire Department of Environmental Services study of the Great Bay raised water quality concerns related to high levels of total nitrogen (TN) and identified the Newmarket Wastewater Treatment Facility as a source. This discovery led to an agreement between the Environmental Protection Agency and Newmarket, giving the town five years to limit TN discharges per day to less than 8 mg per liter.
To address the issue, Newmarket Environmental Services, responsible for providing water and sewer services for the town’s 3,500 residential and commercial users, upgraded its Newmarket Wastewater Treatment Facility with a new four-stage Bardenpho process for nitrogen removal.
The new nitrogen-removal facility was tasked with reducing the plant’s total nitrogen discharge per day from 30 mg per liter to an estimated 5 mg per liter. To meet these treatment goals efficiently, the town needed to invest in an online instrumentation system to control the process.
Newmarket selects the IQ SensorNet system
Newmarket WWTF selected IQ SensorNet because its sensors have a reputation for being long-lasting and easy to maintain. IQ SensorNet is a network of online controllers and sensors designed for process monitoring and control at wastewater treatment plants.
The system continuously monitors water quality throughout the wastewater treatment process, from the influent through the effluent, increasing operational efficiency, lowering operating costs and improving performance.
“It was a really tough decision, but in the end, YSI was the better product,” says Sean Greig, Environmental Services Director for Newmarket. “The engineers can’t believe how well the plants are running.”
Real-time data and cost savings with IQ SensorNet
Newmarket installed a 2020 3G controller system with sensors for pH, oxidation reduction potential (ORP), dissolved oxygen, turbidity, and ammonium and nitrate. Continuous measurements from a pH sensor in the influent and pH and dissolved oxygen sensors in the effluent help operators achieve their treatment goals.
Additional sensors deployed throughout the nitrogen-removal facility enable operators to control the process more efficiently. These parameters can automatically adjust aeration output and chemical dosing based on set points and conditions, resulting in energy and chemical savings.
The IQ SensorNet system gives the Newmarket WWTF access to real-time data, which provides helpful information about how the plant performs and alerts about any issues. This helps operators to optimize processes, increase efficiency, lower energy use, and deliver compliance reporting.
Easy-to-install sensors and reduced lab testing
Thanks to IQ SensorNet’s single cable for power and communication, installing and calibrating new sensors is easier than ever. Pulling sensors from their packaging, connecting them to the network, and programming them into SCADA is simple. No specialists are needed for installation, providing additional cost savings to the organization.
“I’ve had a great experience with the system,” says Sam Heffron, Lab Technician in charge of Operations. “The units have been user-friendly and data-friendly so far, as I can easily track the data. I’ve had to install a couple of units after the fact, and that went well, as it was straightforward. I think we saved a pretty good amount of money by doing that.”
In Sean Greig’s opinion, one of the most significant costs savings from the IQ SensorNet system is the plant’s reduced ammonia and nitrate testing in their water quality lab. Eliminating tests saves technicians time processing samples and reduces costs on laboratory test kits. Time and expenses add up when conducting tests several times a week, 52 weeks out of the year.
“Everyone runs lab tests a little bit differently,” says Sean Greig. “Sometimes, the numbers differ depending on who is doing the test. The probes provide more consistent results and reduce the chance for human error.”
With the new nitrogen-removal facility and the IQ SensorNet system, Newmarket met its target of discharging less than 8mg/L of total nitrogen per day and showed its commitment to improving water quality in the Great Bay Estuary.