Biogas Production from the Co-Digestion of Rice straw with Cow Dung and Piggery Manure

Abstract

The Co-digestion of Rice Straw (RS) with either Cow dung (CD) or Pig Dung (PD) to produce biogas was studied. The objective of this study is to  investigate the suitable mixing ratio of rice straw with cow dung and pig dung for enhanced biogas yield. Different mixing ratios of rice straw, cow  dung and piggery dung were combined and investigated for potential biogas production at an Initial total solid (TS) of 20% in the codigestion  experiments. Results show that a maximum cumulative gas yield (CGY) of 36L/Kg of biogas was obtained in 40 days for a RS-PD ratio of 1:1. Similarly  CGY of 33L/Kg, 32L/Kg and 29L/kg of biogas was obtained for RS-PD ratio of 1:2 and RS-CD ratio of 1:2 and RS-CD ratio of 1:1 respectively.  Co-digestion of rice straw with piggery dung showed marginally higher biogas yields when compared to co-digestion of rice straw with cow dung  suggesting that piggery dung provides a better Carbon/Nitrogen (C/N) ratio leading to increased biogas yield. The results also showed that co-  digestion of rice straw with cow dung or piggery dung showed higher biogas yield when compared with mono-digestion of cow dung or piggery  dung inoculated as control.