State of the Art Report on Methane Fermentation of Biomass

摘要

Research and development on biogas have emphasized technologies for expediting natural methane generation from anaerobic digestion of biomass. This indepth study reviews the status of biogas technology in developing countries and assesses the feasibility and desirability of expanding biogas production. First, based on an extensive review of the literature, the principal technical, social, economic, and environmental issues associated with methane production from farm-and feedlot-scale biogas plants and from marine biomass, urban refuse, and landfill are delineated. The microbiological processes underlying anaerobic digestion and the influences of various environmental factors (e.g., mixing, heating, toxicity, pH, retention time, nutrients) on the digestion process are then described. Raw materials available for biogas, different biogas plant designs (e.g., Chinese, Indian, Philippine, and bag), and the maintenance, operation, and safety of biogas plants are discussed. Next, the composition, fuel value, and processing of biogas are examined; attention is also given to the uses of sludge by-products. The ecological, health, and sociocultural implications of constructing and operating biogas plants in developing countries are reviewed and the status of biogas technology is described. The authors conclude that in both developed and developing countries the energy value obtained through biogas generation is only slightly greater than the costs involved. Thus, a major factor in implementing biogas projects is reclamation of by-products for animal feed and fertilizer. In rural areas where kerosene is expensive and labor inexpensive, a very simple biogas system producing a substantial portion of a family's needs may be feasible, but even in these cases current plant designs may be too costly. Cost effectiveness improves when human waste is incorporated into the system. More than 50 tables and 30 figures are included.