Performance of Upflow Anaerobic Sludge Blanket Reactor with Trickling Filter in Poorly Managed Sewer Network

Due to increased water consumption and pressing environmental requirements of the sewage treatment plant, there is a growing attention in urban area of developing country. Given poorly planned, design and management practice of sewerage infrastructure in developing countries, the performance of well-known biological wastewater treatment options worth to evaluate considering operational and maintenance guidelines. This study aimed at evaluating the operational efficiency of Upflow Anaerobic Sludge Blanket (UASB) reactor with Trickling filter (TF) in the presence of recirculating sludge in treating domestic sewage where the sewer network is poorly managed. The case study performed on Kality wastewater treatment plant in Addis Ababa city. Using standard methods of wastewater examination, the study analyzed the major water quality parameters, such as biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) for 30 days from May 11, - June 9, 2021. The daily average performance efficiency of UASB reactor were 73% removal for BOD5; 66% removal for COD. TSS removal rate obtained 63% which is lower than design value of 70%. Similarly, the performance efficiency of TF with secondary clarifier was higher than 75% and 70% for BOD5 and COD respectively. The overall removal efficiencies obtained are 63 – 91% for BOD5, 64 – 84% for COD, 60 – 92% for TSS. The corresponding effluent daily average concentration are 125mg/l for COD, 62mg/l for BOD5 and 86mg/l; effluent quality design limit is 100mg/L for COD and 35mg/L for BOD5 and TSS. The overall performance of the plant achieved the national environmental discharge limit of inland water with the exception to solids i.e Chromium and Magnesium. However, the effluent quality was not reached the design standard of reusing for irrigation.