Reducing Electrical Grid-Powered Aeration Use and Costs in Reactor Basins
Electrical-grid powered aeration is used intensively in reactor basins at activated-sludge wastewater treatment plants (WWTPs) to supply the mixing and oxygenation needed for digestion. The purchase of electricity is a major part of operational expense, and its use for aeration increases the carbon footprint of WWTPs due to the greenhouse gas emissions associated with electricity generation. Personnel at the Mebane Bridge WWTP in the City of Eden, NC, investigated alternatives to grid-powered aeration to reduce their operational expense and role in causing global climate change.
One alternative suggested by a US EPA qualitative assessment was the use of solar powered circulation (SPC) technology to replace some of the mixing and oxygenation supplied by grid-powered aeration (US EPA 2005). The goal of the initial Eden WWTP study was to meet National Pollution Discharge Elimination System (NPDES) standards while operating a single SPC unit in one reactor basin and reducing aeration. Study objectives were to compare effluent water quality parameters and grid power usage and cost during 1 year of SPC treatment with comparable data from the preceeding year when twelve 20-horsepower (HP) aerators (240 HP total) operated continuously.