Evaluating the Potential of Rice Straw as a Co-digestion Feedstock for Biogas Production in Bangladesh

This research was done to evaluate the potential energy yield capacity of rice straw for anaerobic digestion (AD) as an alternative use of this material. Cattle markets were found to be a potential source that generates a significant amount of a mixture of 80% straw + 20% cattle dung. This waste rice straw/dung mix from cattle markets provides a good mixture with a much better C/N ratio than pure straw. This mix of straw and dung are often left in piles in the market for between 10 and 20 days, where they degrade naturally. Tests involving feeding this mixture into a domestic biogas plant showed that the biogas yield is 0.099 m3/kg feed stock with a methane content of 74.43%. . In the whole of Bangladesh there are 500 cattle markets, so their waste can produce about 35,000,000 MJ of energy through AD. A biogas plant will continue to generate biogas, even after daily feeding has been stopped, although the gas production and the methane content do reduce with time.