Design and Cost Comparison of Extended Aeration and SAFF for Typical Domestic Waste Water

Abstract

In the present study we have done the feasibility study of two different technologies viz.extended aeration and SAFF, used for the treatment of sewage.Before comprising the techno-economical feasibility of two different technologies, we have designed STP with both the technologies. Design basis of STP for a typical domestic waste water at the flow rate 100 KLD. BOD of untreated effluent and treated water is 300 and 30 mg/l respectively. Cost estimation of each individual unit is based on the consultation with different suppliers and technically associated personnel of various organizations. The economical feasibility is dependent on civil and mechanical cost of each of the unit and both these factors are governed by current market values. The basic design (O&G trap, bar screen, Equalization tank, Primary clarifier, Secondary clarifier and Sludge drying bed) is same for both the technologies except aeration tank and SAFF reactor. We estimated the civil cost as Rs 1042900 and Rs. 951650 for aeration tank and SAFF reactor respectively, while mechanical cost as Rs. 195064 and Rs.203189 respectively. So we can say that the cost can be reduced if we use SAFF technology for the treatment of typical domestic waste water. On the basis of present study we observed that media provide more surface area to microorganisms for their rapid growth. Volume of SAFF reactor is reduced by 1/5 than that of extended aeration. MLSS concentration and DO maintenance dose not require for SAFF. These observations prove that SAFF technology is more techno-economical than extended aeration.