BIOGAS yield from Anaerobic batc h co-digestion of RICE STRAW and zebu dung

The suitability of rice straw waste biomass for anaerobic digestion was tested and the energy potential of the co-digestion of rice straw with zebu dung was examined. Rice straw and zebu dung were studied under batch anaerobic conditions as separate wastes as well as mixed in various proportions. All experiments were carried out at 5% of total solids. The methane yields achieved by single substrate digestion of rice straw and zebu dung were 60.51 l CH4 kg–1 volatile solids (VS) and 96.09 l CH4 kg–1 VS, respectively. The highest energy potential was reached by co-digested mixtures 80 : 20 and 60 : 40 (rice straw : zebu dung) giving the methane yield of 163.23l CH4 kg–1 VS and 138.96l CH4 kg–1 VS, respectively. According to these results, rice straw is suitable for the energy production through the anaerobic digestion. The degradation and methane production potential of rice straw is significantly increasing when co-fermented with zebu dung. The most appropriate proportions for co-digestion were determined as 8 : 20 and 60 : 40 (rice straw : zebu dung), because it was found that with the increasing content of rice straw up to the ratio 80 : 20, the amount of produced biogas increases due to the optimization of pH of the mixture.