LAUSR

Abstract In general, human faeces disposal in India is into open lands, nallahs and rivers without treatment and has very high content of nutrients, organic matter and pathogens. Human faeces can cause adverse environmental and health problems (due to pathogen contamination, odour etc.) in the absence of appropriate disposal methods. This study was carried out to compare the rate and amount of biogas produced from co-digestion of human faeces (HF) with poultry litter (PL) & cow dung (CD) under anaerobic conditions. A laboratory scale simulation digesters (D) was set up with three different proportions of substrate i.e D1–100% HF, D2- 50:50 HF+PL and D3- 40:60 HF+CD and the study carried out for 52 days at room temperature between 25 to 35 °C. In each case, the feedstock was diluted with equal volume of water to form slurry. The daily biogas production for each anaerobic digester was recorded using the water displacement method, and the corresponding cumulative biogas volume was calculated. The result obtained from this study shows that a total of 7.62  × 103 ml, 9.85  × 103 ml and 12.96  × 103 ml of biogas were produced from HF, HF+PL and HF+CD, respectively. Thus, the co-digestion of human faeces with cow dung (HF+CD) gave a better biogas production may be due to the maximum COD reduction and optimum C/N ratio as well as fast bacterial action on cow dung relative to the poultry litter and human faeces. Pathogen inactivation was inefficient after the anaerobic digestion of waste as the reduction in the number of E. coli and Enterobacteriaceae was only by one logarithmic unit The highest biogas yields were observed at pH 7.52, 7.9 and 7.63 for HF, HF+PL and HF+CD, respectively. The COD reductions were 42.97, 47.5 and 52.99%, for D1 (HF), D2 (HF+PL), and D3 (HF+CD) digesters, respectively. To control spread of human faeces disease and protect fragile environment, it can be used for biogas production, combustion as fuel, biochar production, in building materials and as a soil conditioner.