Maintains the optimum environment for microorganisms by maintaining constant sludge age (SRT); maintains optimum conditions for thickening of the wasted sludge by providing stable mass loading. Improves water quality and saves up to 15% of energy costs by maintaining constant dissolved oxygen concentration (DO). Solves operational problems and achieves energy savings of up to 25 percent by selecting optimum DO and SRT targets. Improves plant reliability, reduces pumping costs, and increases biogas production by maintaining constant depth of sludge blanket in clarifiers and gravity thickeners.