A fast-growing city in the arid desert regions of the western U.S. recently addressed the need to expand its municipal service for new residents and subdivisions. In recent years, the city’s residential demand for wastewater treatment tripled from less than 1 million gallons to more than 1.5 million gallons per day. In planning for the wastewater treatment plant’s expanded capabilities, the city’s water engineers identified minimizing aeration basin compressed air energy costs as a goal.
In wastewater treatment plants, a variety of processes are employed to eliminate organic pollutants from water to ensure it meets sanitary requirements for future use. One of the most common processes is the activated sludge method, which biologically treats the wastewater through the use of large aeration basins. This process requires the pumping of compressed air into the aeration basins where a diffuser system ensures the air is distributed evenly for optimum treatment. The energy needed to provide compressed air is a significant cost in the operation of a wastewater treatment plant.
Tiny microorganisms in the aeration basins decompose biologically degradable organic solids in the wastewater. These microorganisms depend on the aeration system to provide the right amount of air necessary for them to thrive and consume the suspended solids in the wastewater. These solids are eventually removed downstream of the aeration basin and can be digested to create energy at the plant.