Anaerobic treatment of wastewater using an upflow anaerobic sludge blanket reactor

ABSTRACT An upflow anaerobic sludge blanket (UASB) reactor of volume 0.03 m3 was designed and fabricated to treat wastewater. The initial organic loading rate (OLR) of the wastewater estimated to be 4.8 gVS/l.d was later reduced to 0.96 gVS/l.d to control the observed acidity in the medium while the reactor was operated continuously for 64 days. The percent biological oxygen demand (BOD) and volatile solid (VS) removal were calculated over a period of 5 weeks to measure the efficiency of the reactor. The mean VS, total solid (TS), and BOD for the influent substrate were 0.43 g/kg, 0.84 g/kg, and 0.020 mg/m3, respectively, while for the treated wastewater, the VS, TS, and BOD were 0.30 g/kg, 0.59 g/kg, and 0.013 mg/m3, respectively. The estimated energy produced by the biogas was 5.8 kWh and 0.001 m3 of the biogas raised the temperature of 20 ml of water by 11.8°C in 40 s. The study concluded that the UASB reactor designed could treat the wastewater and the biogas generated could also serve as a source of renewable energy for cooking. However, the start-up OLR should be monitored in the course of operation to prevent souring of the digester and to achieve optimum performance of the reactor.