Control change would reduce aeration blowers' energy cost by 5% overnight

SAM4 Energy identified a change in blower station control strategy that would instantly start saving this wastewater treatment plant €120k a year, with no capital investment required.

Aeration is easily the most energy-intensive process in the wastewater treatment process, responsible for up to 60% of a treatment plant's power consumption. Five rotary lobe blowers in an activated sludge plant (ASP) at a wastewater treatment works were consuming more than six gigawatts of energy per year, at a cost of €1.3 million. The blowers in a second ASP at the same treatment works showed similar behavior.

SAM4 Energy was installed on the blowers to find any room for improvement. After analyzing the blowers' real-time operational data, SAM4 Energy determined that part of the high energy demand was due to short operation cycles below the blowers' nominal speed.

Suboptimal control logic meant that multiple assist blowers were being run at low speeds. Operation below nominal speed and flow is less efficient and uses unnecessary power. Over 5% of the energy consumed was being wasted in this way.

Our Energy team advised the customer to improve the existing control strategy at both ASPs by increasing the speed of the blowers already running before switching on an additional blower, as well as extending the delay time for an additional assist blower. These two simple changes would instantly reduce the number of low-speed operational cycles. Based on six months of operational data, we calculated that this would reduce the blowers' total energy consumption by 5%.

Once implemented, this simple improvement will save the customer 268 metric tons in carbon emissions and €120,000 in energy costs per year.