Energy Savings via Waste Water Treatment Plant (WWTP) Optimization: Ingersoll, Ontario WWTP
R.V. Anderson Associates Limited
Harpreet Rai, PhD, P.Eng, BCEE
Ingersoll WWTP has two liquid trains including the 1974 plant with rated capacity of 4,500 m3/d and the 2018 plant with rated capacity of 8,445 m3/d. The current average flow to plant is approximately 7,500 m3/d, which is 58% of the plant’s rated capacity of 12,945 m3/d. With the plant operating significantly under capacity, the County retained RVA to evaluate operation optimization options to reduce aeration energy.
RVA prepared a calibrated BioWin model of the plant to establish the current operation conditions, identify aeration-optimization measures, and predict performance with identified optimization measures. The model was used to identify the best possible operation scenario for energy optimization, and the necessary process adjustment of operating parameters like HRT, SRT, and were established for maintaining the required effluent quality. In addition, RVA identified hardness-based fouling of the ceramic diffusers causing low oxygen transfer efficiency and recommended their replacement with membrane diffusers to further enhance the annual energy saving.
The optimization plan was implemented with the optimum flow-split option and shutting down half the aeration tankage. The MLSS and operating SRT values in the 2018 were adjusted to match the ones recommended, and the existing ceramic diffusers were replaced with membrane diffusers. The implementation of the recommended optimization measures has reduced the WWTP aeration energy demand by more than 50% with the plant currently operating with only one blower at approximately 60%, compared to two blowers running at 90% previously. This has resulted in annual energy saving of 230,000 kW-h translating into $37,000 per annum.
—Poster presented at ISI’s third annual Virtual Conference (November 16 – 17, 2022)