Bio-Methane Potential of Biological Solid Materials and Agricultural Wastes

This research studied the bio-methane potential of biological solid materials as alternative sources for biogas production. An agricultural residue (rice straw), wastes from four agro-industries, (cassava pulp, pineapple peel, decanter cake and empty fruit bunches) and two weeds (cat-tail (Typha angustifolia L.) and water hyacinth (Eichlornia crassipes Solms)) were evaluated as substrates for biogas production. The methane potential assays varied from 0.34 to 0.40 m 3 CH4 kg −1 VSadded. The maximum specific methane production rates comparing extent and digestibility of each material in a descending order were that of pineapple peel of 36.77 ml CH4d -1 , cassava pulp of 36.57 ml CH4 d -1 , decanter cake of 32.86 ml CH4 d -1 , empty fruit bunches of 13.48 ml CH4 d -1 , cat-tails of 11.63 ml CH4 d -1 , water hyacinth of 11.57 ml CH4 d -1 , and rice straw of 10.98 ml CH4 d -1 . Rm values depended upon the substrates readily degradable composition and proportions, including lignocellulosic compounds. All experiments on biogas productivity were conducted for more than 90 days to reach the final yield. The experimental results revealed that bio-solids could be potential sources for biogas production, while further improvement of biogas yield and process flexibility in terms of various feedstocks is necessary.