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.