Use of Online Nutrient Monitoring for Automatic Aeration and Nitrate Recycle Pump Control

The Northside Wastewater Treatment Plant (WWTP) in Kinston, NC was expanded and upgraded in 2006 for biological nutrient removal (BNR) to meet limits of 3 mg/L total nitrogen (TN) and 1 mg/L total phosphorus (TP). In addition to the traditional approach of controlling the blowers based on dissolved oxygen (DO) readings, the City decided to implement an aeration basin blower control system using readings from an online nutrient monitoring system. With the availability of online nutrient readings, the blower system has the capability to operate based on the actual level of wastewater treatment desired and obtained. The online nutrient monitoring system also can be used to control nitrate recycle pump speed to optimize anoxic zone performance. This paper will provide a discussion of the aeration and nitrate recycle control schemes, challenges encountered during the preparation of specifications for contractor bidding for the development of these tailored control schemes, and results from the troubleshooting and start-up of the control system.