How does Activated Sludge work?
Referring to the above illustration: PLANT INFLUENT is the raw wastewater that arrives at the facility. This is normally about 80% domestic sewage and 20% industrial wastewater. During wet weather, groundwater infiltration can triple the facility s normal flow of 6 million gallons per day (MGD). After screening to remove large particles, the flow is directed to one or both of the two 487,000 gallon Primary Clarifiers. Flow in these large tanks is slow enough to allow settleable matter to sink to the bottom as Primary Sludge, where it is removed to the sludge disposal system. Flow leaving the Primary Clarifiers (Primary Effluent) still has significant impurities in the form of dissolved and colloidal organic matter. Primary Effluent is combined with Return Activated Sludge and sent to the eight, 390,000 gallon Aeration Basins. Return Activated Sludge is a thin sludge containing agglomerated particles of organic solids (called floc ) and live microbes. In the Aeration Basins the microbes
