Energy Reduction and Nutrient Removal in WWTPs Using Feed-Forward Process Control

Aeration is by far the largest electrical consumer in a wastewater treatment plant (WWTP), accounting for greater than 50% of total energy consumption. Typically, DO set-points are based on peak loading and are therefore much higher than what is needed for the majority of the day. Lowering DO set-points can have a significant impact on total energy consumption of a plant. A real-time, model-based process control system that calculates optimal DO set-points to treat the incoming loading without compromising effluent quality can reduce aeration and hence energy requirements. The process control system can also control mixed liquor recycle in a BNR plant, to maximize denitrification in the anoxic zone, thereby maximizing Total Inorganic Nitrogen (TIN) removal.Pilot projects in Phoenix, Arizona and Enfield, Connecticut demonstrated aeration energy savings of 15% to 17% and improved TIN removal by over 35%.