Latest Innovations in Nutrient Removal Optimization


  • Katya Bilyk - Hazen and Sawyer

The purpose of this presentation is to provide quantitative examples of nutrient optimization strategies that different North Carolina municipalities have used to optimize nutrient removal and reduce operating costs.

Examples of the strategies that will be presented shall come from the following facilities, each of which utilize dedicated anaerobic, anoxic, and aerobic zones:

· Plant A had discharged an average TN of 2.5 mg/L and TP of 0.22 mg/L using glycerin and ferric. After implementing a new dissolved oxygen (DO) control strategy that reduced their operating DO setpoints they were able to maintain the same level of effluent quality and discontinue use of glycerin and ferric. The aerobic SRT (14 days) was ample for nitrification even at the reduced DO values. The total SRT is 30 days. The facility uses a mixed liquor fermentation zone to sustain its biological phosphorus removal population.

· Plant B has reduced its effluent by about 3 mg/L with the addition of sidestream deammonification, reduced DO setpoints, and baffle wall modifications to correct back mixing of air into the anoxic zone. The 12-month running average TN is about 5 mg/L without supplemental carbon. Monthly electrical bills are down about 20% compared to bills prior to the upgrade.

· Plant C discharged an average TN of 2.2 mg/L and TP of 0.07 mg/L with efficient use of glycerin, ammonia-based load equalization, ammonia-based DO control, and automated SRT control. Average SRT has been 16 days.

· Plant D has averaged an effluent TN of 1.8 mg/L and TP 0.6 mg/L since July 2014 without supplemental carbon addition using an enlarged first anoxic zone, high internal recycle flow rate, and 22 day SRT.

This paper will also summarize how to incorporate the latest innovations in nutrient removal optimization into designs. The topics shall include mixed liquor fermentation, SRT control, sidestream treatment, ammonia-based DO control, ammonia-based load equalization, and enlarged anoxic zones.

For more information, please contact the author at

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Horizons showcases significant water, wastewater, reuse, and stormwater projects and innovations that help our clients to achieve their goals, and can help you achieve yours. Articles are written by top engineers and process group leaders, demonstrating and explaining the beneficial application of a variety of technologies and tools.

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