Temperature effects on anaerobic digestion of faecal sludge (Nepal)

Production of biogas from human faeces could transform the way sanitation- related issues are managed. Just 7% of wastewater collected from sewered systems is safely disposed after treatment. Methane is a powerful greenhouse gas that, on a mass basis, is around 25 times more potent than CO2 over a 100-year period. The performance and efficiency of anaerobic digestion can be improved, by understanding the difference between mesophilic and thermophilic conditions. Anaerobic digestion is the preferred technique for treating sewage and other organic waste such as animal dung, wastewater bio solids, faecal sludge and food wastes. Further improvement of anaerobic process will increase its efficiency in pollutant removal, gas generation and useful in deciding how sludge is digested. Faecal sludge was examined for the changes in various parameters in two temperature ranges, namely thermophilic and mesophilic. The sample was digested in water bath for 40 days and the gas produced was measured in daily basis. Thermophilic digestion can be adopted if more bio methane or more reduction in VSS and COD are desired. In thermophilic conditions, the rate of VSS declination was quick compared to the steady rate of declination in mesophilic system.