Improving Energy Efficiency and Performance of Wastewater Recycling

Project Update

Experiments for nitrogen removal in the 1000 L pilot scale raceways were used to guide operational modifications and optimizations of the full-scale raceway system, resulting in lower total nitrogen in the effluent later into the fall and early winter than in previous years. In 2022 and 2023, research focused on achieving total nitrogen limits < 10 mg/L in the effluents of the full-scale facility particularly in winter months. Over the course of the last three years the optimization of the RNEW® process resulted in a 10-25% increase in nitrogen removal and was able to decrease the amount of aeration needed by 15%. The ultrafiltration pilot studies concluded and the results indicate that tangential filtration, while consistent at producing a high-quality treated effluent regardless of feed quality, was not an economically viable option for polishing secondary-treated effluent from a heavily loaded conventional pond system. Further research into the use of crossflow membranes operated in dead-end configuration with intervals of high-flow crossflow flushes may be warranted as a low-cost alternative to outside-in membranes (which require air scouring). Modeling of this process is nearly complete and operational guidelines for use in future process and facility designs were developed.