Decentralized Wastewater Treatment System (DEWATS or DWTS) for Medium Strength Domestic Wastewater

Abstract

Wastewater collection and treatment has always been a challenge for developing countries because of lack of infrastructure for transport and treatment. Most of the areas in developing countries lack proper sanitation facilities and sewer network due to which centralized treatment become impossible. In such cases, Decentralized systems may be installed to treat the water on site. In this study, performance of Decentralized Wastewater Treatment System (DWTS) was studied. The lab scale DWTS comprised of Anaerobic Baffled Reactor followed by Anaerobic Filter and finally effluent was filtered through Woven Fiber Micro Filtration (WFMF) membrane. ABR was run at 3 different HRTs i.e. 8, 10 and 12 hours. During the whole run of around 8 months, the average COD removal efficiency in ABR was found to be 65, 68 and 72% at HRT of 8, 10 and 12 hours, respectively. AF was run with 4 different media i.e. Kaldnes K1, PVC pipe 25 mm length, PVC pipe 20 mm length and PVC pipe 15 mm length. The diameter of the PVC pipe was 15 mm. The average COD removal efficiencies in Kaldnes, PVC 25, PVC 20 and PVC 15 were found to be 86.5, 84, 85 and 86%, respectively. The membrane reactor was run with Microfiltration Woven Fiber (WFMF) membrane with nominal pore size of 1-3microns. The average COD and Turbidity removal efficiency shown by this whole system was 96 and 98%, respectively. This membrane system ran successfully for 37 days showing a gradual increase in TMP with the passage of time. On 37th day of run, the membrane reached the TMP of 20kPa, an indication of a fouled membrane.