The extended aeration process is an advanced activated sludge process which involves treatment of primary clarified effluent with a culture of microorganisms called “mixed liquor/Biomass”. This mixed liquor is retained in the aeration tank and an adequate oxygen source is provided for biological activity and to keep the “mixed liquor” in well mixed condition. The microbes consume the organic waste in the effluent leading to biomass production. The suspended solids and biomass are separated from the treated water in a secondary clarifier. Part of the biomass is returned to the aeration basin as return activated sludge (RAS), to keep the required MLSS level in the aeration tank. The BOD removal efficiency of the extended aeration process is higher than the conventional activated sludge process.