Abstract: Many of the food crops after being harvested are sent to processing for further use. During the processing operations, large amount of waste is generated, which needs to be dealt with in a sustainable way. Huge quantities of waste resulting from crop cultivation action and animal waste like manure and poultry droppings are a likely-looking source of energy supply for manufacture, treating and domestic activities in rural areas of the concerned region. The available crop residue and other solid biomass can be used effectively. There is virtually an unlimited potential of bio-energy in our country. Traditional method of waste handling is generation of biogas from it. The residues are introduced into the anaerobic bio-reactor, after that conversion of solid residue into biogas takes place by means of anaerobic microorganisms like Methanogenic bacteria. After the completion of the process the remaining solid waste can be utilized as bio-fertilizers. Both pollution control and energy recovery can be achieved efficiently in bio gas production by anaerobic digestion without intake of any external electron acceptor like oxygen having some limitation in terms of demerits including inhibition problem which has to be overcome by some means. Here in this review paper the intricacies of the anaerobic digestion process, different stages of the process are covered and a summary of the various types of substrates used and the results obtained in each case are reviewed.
Keywords: Biomass, anaerobic digestion, micro-organisms, biogas, methane.