H4-KH-20-D bly required auxiliary cooling is dependent on the Helical speed reducers H4

Flender/Flender Gear Units/Helical speed reducers H4

ion and Utilization of Biomass 8 6.5 Anaerobic Biogasication The anaerobic decomposition of organic matter to methane (CH and carbon dioxide (CO is called biogasication . Though the process of biogasication has been known for long time, its potential for converting various substrates ranging from animal secretory products to municipal wastes into biogas has been realized recently. Now different designs of biogasication plants are in use. Biogas can be utilized for operating diesel engines, lighting, cooking, and other heating purposes as well. The main advantages of biogasication are as follows: The biogas contains higher percentage of methane (about 6%). The digested material containing signicant amounts of nitrogen and other soil nutri- ents can be utilized as an organic fertilizer. The overall thermal efciency of burner using biogas is fairly high.The biogas can be puried to methane enriched fuel. simple design for biogas plant is available, and it can be manufactured locally. 6.5.1 Principles The conversion of biomass to CH 4and CO 2during anaerobic fermentation occurs by the concerted action of three main groups of bacterianamely, fermentative, acetogenic, andmethanogenic bacteria. The fermentative bacteria hydrolyze the raw organic substratesmainly to acetate, fatty acids, CO 2, and 2. The 2producing acetogenic bacteria produce H2, acetate, and sometimes CO 2. The methanogenic bacteria mainly catabolize acetate, CO 2, and 2to CH 4and other compounds (. 6.5.2 Factors Affecting Anaerobic Biogasication The main factors that affect the formation of biogas from an organic substrate are: tempera- ture; pH; percentages of and , solid organic matter, and water in the slurry; retentiontime; loading rate; and nutrients. For improving the efciency of the biomethanation process it is important to nd suitable mixture of substratesnamely, algae, water hyacinth, cow dung, etc. Single substrate provides suboptimal carbon-to-nitrogen ratio, thus restricting t