Optimizing Chemical Dosing Reduces Chemical Use while Meeting Effluent TP Limits

Black River Falls, Wisconsin


Wastewater treatment plants (WWTP) are facing many challenges.  Permits on nitrogen and phosphorus in the effluent water are progressively becoming stricter in order to protect surface waters from eutrophication. At the same time, plants are required to reduce both energy and chemical consumption and are often challenged with limited time and staff. In total, they are required to do more with less.


The OSCAR system with NURO controller adjusted aeration of the process to the current requirement. Excess aeration during low loaded conditions wastes energy and also causes unstable control and wear on the blowers. By automatically detecting low loaded cycles, the NURO controller reduced energy consumption as well the number of blower starts. During summer operation, energy consumption was reduced by 22% and the number of blower starts by 50% compared to operating the basin without nutrient control. Chemical usage was also down during this time period by 55%. During the winter, energy savings of 10% was reached despite the process operating at 7°C.


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