| dc.description.abstract | The focus of this study is assessing and exploring the potential of anaerobic treatment for municipal wastewater of low- to medium strength (i.e., 212 mg/l COD and 931 mg/l COD) for converting organic matter into methane in up-flow anaerobic sludge blanket (UASB) reactors. Two laboratory-scale UASB reactors were set up in the study and was investigated for 76 days; one reactor (Reactor Vik) treated medium strength wastewater; and the other reactor (Reactor SNJ) treated low strength wastewater. The performance of the reactors was assessed based on the efficiency of chemical oxygen demand (COD) removal and their ability to generate methane. Reactor Vik obtained an average COD removal efficiency of 60% towards the end of the operating period, while Reactor SNJ attained an average COD removal efficiency of a negative 3%. The methane production increased with an average of 40 ml/d when the OLR increased in Reactor Vik. However, there was an overall lack of methane production despite increase of OLR in Reactor SNJ. The results obtained indicate a significant COD removal efficiency and methane production when treating medium strength wastewater in Reactor Vik, in contrast to the treatment of low strength wastewater in Reactor SNJ. The observation of high sulfate concentration in Reactor SNJ led to a hypothesis suggesting that the reactor is inhibited by hydrogen sulfide. The average methane yields obtained in the last 10 days of observation in Reactor Vik were 0.43 gCODCH4/gtCOD removed and 0.49 gCODCH4/gsCOD removed. Under these conditions, approximately 41.6 GJ/d of energy which is equivalent to 4624 kWh/d of electricity could be recovered at IVAR Vik wastewater treatment plant which has approximately 8000 m3/d of average hydraulic loading based on an estimated daily removal of 3083 kg solauble COD. Anaerobic treatment using UASB reactor for treating the medium-strength wastewater at IVAR Vik wastewater treatment plant represents a feasible and promising alternative as pre-treatment for the aerobic biological treatment. Through this process, a reduction to 250 – 300 mg/l soluble COD is achieved, and organic matter is converted into economically valuable products as methane with a production rate of 1080 m3/d.
Keywords: anaerobic treatment, UASB reactor, COD removal efficiency, methane production | |
