Yoshihiro KIRISHIMA

Evaluation of the Performance of Sewage Treatment Process with Minimum Energy Requirement and Applicable to Developing Countries

Hideki HARADA, Akiyoshi OHASHI

In developing countries, UASB (Upflow Anaerobic Sludge Blanket) system is increasingly popular as a minimum energy requirement sewage treatment system. But it is required appropriate post treatment because of its poor effluent quality. Our proposed system 1000 m3/day capacity DHS (Downflow Hanging Sponge) demonstration plant has constructed as a cost effective post treatment system of UASB in Karnal, India. The system performance has been evaluated for 400 days. The qualities of DHS effluent and FPU (Final Polishing Unit = Stabilization Pond) effluent were also compared during whole experimental period. The HRT and recirculation ratio for DHS system were 1.5 hours and 100% in regular operation. Recirculation ratio of DHS system was changed for evaluating the performance of different organic loading and HRT in the later period. Ambient temperature (around 9 AM) in this study period was harsh condition ranging from 5 to 40 ��C. The results demonstrated that DHS system has excellent and steady performance in removal of BOD 96%, SS 95%, NH4-N 76% and Fecal coliform 99%. DHS system could be maintained on high performance even in low recirculation ratio and low temperature periods as well. Furthermore, it clearly showed higher performance of DHS system in removal efficiency compare with FPU system.