Sludge is a generic term for the solids removed from any plant. These solids are treated at this facility by aerobic digestion. This is a natural biological process that utilizes existing bacteria to stabilize the solids. The stabilized sludge, called biosolids, must meet many strict State and Federal requirements before it can be applied to farmland. The liquid biosolids are pumped to the centrifuges where it is dewatered to approximately 20% solids concentration. The dewatered biosolids have a look of damp rich soil and has an earthy/slightly musty odor.