Biogas

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Organic Matter Decomposition Degradation of Plant Residues Humus Genera of Microorganisms Capable of Utilising Different Components of Organic Matter Humic Acids Beneficial Role of Humic Acids

Biogas

Biogas
Cattle-dung is a good substrate for anaerobic fermentation by methane bacteria. The fermentation of cattle-dung in specially designed and inexpensively fabricated plants not only provides cooking gas for the farming community by way of methane, but also leaves behind a slurry which can be used as an organic .manure for growing crops. From laboratory experiments, it is now known that digestion of cattle-dung for 4 weeks at 30ºC is necessary to achieve good gas production of about 1.5 cu ft/lb of fresh bullock-dung. The composition of the gas is approximately 55-60% methane, 5-10% hydrogen and 30-35% carbon dioxide.

Biogas

On the Left is a Sketch of the Biogas Plant Designed by Acharya at the Indian Agricultural Research Institute; A-brickwall; B-gas; C-cowdung inlet pipe; D-pulley; G-cowdung mixing tank; H-drying bed; L-ground level; n-gas moisture exit trap; O-slurry level; P-fermentation tank; R-iron rods; S-counterpoise weights; T-gas outlet pipe on the right is a photograph of the biogas Plant

On the Left is a Sketch of the Biogas Plant Designed by Acharys at the Indian Agricultural Research Institute; A-brickwell; B-gas holder; C-cowdung inlet pipe; D-pulley; G-cowdung mixing tank; h-drying bed; L-ground level; N-gas moisture exit trap; O-slurry level; P-fermentation tank; R-iron rods; S-counterpoise weights; T-gas outlet pipe On the right is a Photograph of the Biogas Plant

Dilution of the dung (1 to 1½ times with water) to bring the level of solids to about 7 to 9% has been found to increase the gas production. Addition of nutrients like nitrogen, phosphoric acid, potash or minor elements will not augment gas production but supplementation of the dung with organic materials rich in cellulose and protein (sunnhemp, dhaincha, groundnut shells and sugarcane bagasse) increases gas production. On the other hand, organic materials rich in fermentable carbohydrates like jaggery, molasses, potato and maize do not contribute to increased gas production.

The rate of gas production falls during winter in several parts of North India since temperatures below 15°C are not conducive for the activity of methane bacteria (Table 34). The sluggish rate of fermentation in a biogas plant in winter could be overcome by providing a casing to the fermentor so as to conserve heat. Alternatively, temperature insensitive methane bacteria may have to be evolved to allow fermentation at a wide range of temperatures.

Influence of Atmospheric Temperature on the Fermentation Liquor at Different Depths

Atmospheric temp. (*C)			Temperature in ºC at depths of cm
	0	30	90	150	210	270	330
15.5	14.0	15.0	17.5	19.0	19.0	18.5	17.5
18.0	16.5	17.5	19.5	21.0	22.0	21.5	20.0
19.5	18.0	20.0	21.5	22.5	23.0	22.5	21.0
22.5	20.5	220	24.0	24.5	25}0	25.0	24.0
25.0	23.0	24.5	27.0	28.0	28.5	28.0	27.0
28.5	26.5	28.0	29.0	31.0	31.5	31.5	30.0
31.0	28.5	30.0	32.0	33.0	34.0	33.0	32.0

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Mineralization and Immobilization Process Effects of Residues of Crops on Plant Growth Soil Sickness Composting Vermicomposting Green Manure Anaerobic Decomposition of Organic Matter Biogas Degradation of Hydrocarbons

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