Renewable energy production and environmental crisis are the recent issues prevailing in the society. Economic growth of the country depends largely on the availability of the renewable energy. Wastewater treatment systems are huge consumers of electricity for accomplishing the task of a safe and healthy environment. Wastewater systems account for about 1- 5 % of total electricity consumption in a country. It is stated that energy consumption contribution per person is about average values of 12-15 kWh/ person-year considering 80% of water @ 180 L per capita per day is contributing to sewage reaching to STP for treatment and BOD of 50g/d. Hence, there is an urgent demand for reducing this consumption for an overall development of our country. Among the aerobic processes, activated sludge process (ASP) represents the most widespread technology for wastewater treatment in India. In ASP major part of the energy consumption (about 60%) occurs in the aeration tank to provide a proper environment for the treatment of wastewater. In wastewater treatment plants, it is very difficult to make power savings in general because the process is continuous, and, on the other hand the treatment technology is based on processes (physical, chemical and especially biological) that cannot be switched off or disconnected from the main supplies. The other option is only to modify the processes in order to save energy. A case study for performance analysis of conventional Activated Sludge Process with use of excess sludge as a flocculent in the Primary Settling Tank was carried out to enhance the operational efficiency of secondary treatment unit and improve the settling characteristics in the Primary settling tank. The performance was assessed by setting up a laboratory scale ASP setup and commissioning the reactor at suitable HRT of 6h scaling down it from 12h. The study aims at improving the settling property of primary settling tank thereby reducing the organic load in aeration tank and reducing the energy consumption of the treatment plant. Many encouraging results were observed which supported the concept that efficiency of primary settling tank can be increased by the addition of the suitable quantity of activated sludge. It was observed that compared to the conventional control (all recycled biomass going to AT), the improvement inorganics removal in our modified system was 38% at 30+40% recycle combination. This can result in overall reduction of the maintenance cost of STP plants in our country.