In Extended Aeration, This process takes raw sewage directly into an aerated mix tank for 8 h or more to provide bacteria with optimum conditions to consume the BOD present in the wastewater. The effluent from this mix tank goes to a sedimentation tank where the flocculated colonies of organisms are settled to produce a clear overflow.

Extended Aeration Process Scheme.

A portion of the settled microbial floc is returned to the head works and a portion sent to sludge disposal. The clear effluent is then directed to final treatment such as disinfection, perhaps passing through a final polishing filter. This method of
treatment is particularly suited to plants that have a low concentration of settleable solids in the raw sewage. It minimizes the number of unit operations involved in smaller plants.

If You Liked This Post Do Share it with the World!