Biogas Production from Anaerobic Digestion of Biodegradable Household Wastes

Abstract

This study focuses on production of biogas as an alternative energy by using biodegradable wastes (BWs) in view of solving waste management at household level. The research was conducted on ARTI model compact biogas plant of 1 m³ digester and 0.75 m³ gasholder in focusing the management of daily collected biodegradable wastes (1-2 kg) produced from households. Both laboratory and field analyses were carried out. Methane content in biogas was determined by Biogas Analyzer Gas Board-3200P. Average maximum of about 235 l gas was recorded per day with corresponding to 65 min/day burning hour with the gas flame of energy value 1.55 MJ/h. According to the plant owners, the burning period of the gas was approximately 2 h/day during the spring and pre-monsoon seasons. The average gas production (per kg) from fresh waste materials was approximately 60 l. The use of high moisture containing cellulosic waste materials and incomplete digestion due to lower digester temperature were the major causes of lower gas yield. The proportion of methane exceeded by carbondioxide in the beginning but then after gradually methane exceeded carbondioxide and reached 56.43% on an average. Although fertilizer value in terms of NPK increased gradually but it remained below 1% except K, which was found to be 1.22%. Simple payback periods of 4.81, 7.57 and 7.20 years were found in kerosene, firewood, and LPG substitutions respectively.

Key words: alternative energy; biogas analyzer; compact biogas plant; methane; simple payback period

DOI: 10.3126/njst.v11i0.4140

Nepal Journal of Science and Technology 11 (2010) 167-172