Abstract
Cow manure is one of the promising sources of biogas. However, due to poor biodegradability of fibrous material that is present in the total solid (TS) content, the optimal biogas yield is not achieved. The main purpose of this study is to examine the effect of enzymatic hydrolysis pre-treatment of lignocellulose rich substrate to enhance the biogas production. Biogas production of cow manure was investigated using two anaerobic reactors (R1 and R2) in batch mode. Reactor R1 (controlled) was operated using cow manure as the sole substrate and reactor R2 consist of cow manure and mixed fungal, as inoculum. Each vessel consists of 3 L substrates, operated at the temperature of 35 °C and pH controlled at 6.9. The stirring was maintained at 150 rpm. Effluent was subjected to several analytical tests which includes chemical oxygen demand (COD), ammonia nitrogen content (NH3-N), total solid (TS) and volatile solid (VS). Lignin, cellulose (as glucose) and hemicellulose (as xylose) were investigated using van Soest Fiber Analysis System and HPLC, respectively. Result indicated that, raw cow manure constitutes about 11.9 wt% of TS, with VS content of 10.7 wt%. The degradable fractions of cow manure consist of 25.44 % of cellulose with13.43 % of hemicellulose and 13.36 % lignin. Glucose and xylose indicated in raw cow manure was about15.39 g/L and 10.92 g/L, respectively. Apparently, the results on the biogas production from reactor R1 at 30 d operation showed this sample produced slightly higher than reactor R1 about 6.91 L compared to reactor R2 (6.5 L). This study indicated that the raw cow manure which is without any pre-treatment could be potentially considered as one of the most effective alternative for generating biogas.
