Solid state anaerobic digestion of cattle dung and rice straw for biogas production
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Date
2009
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Publisher
CCSHAU
Abstract
Anaerobic digestion is gaining importance for agriculture and agro industries
because the process couples the advantage of an energetic use of renewable resources
with effective protection of environment. It has role in biogas recovery and production
of organic manure. In India most of biogas plants are based upon cattle waste as
substrate. Rice straw disposal is a challenge for rice growers. During present
investigation digestion of cattle dung supplemented with rice straw at high solid
concentration was studied. Cattle dung and rice straw were mixed in ratios 1:00, 1:
0.31, 1: 0.63, 1: 0.78 and 1: 0.94 on dry matter basis corresponding to 0, 5, 10, 12.5 and
15 % on fresh weight basis. After mixing of cattle dung and rice straw in above
mentioned ratio total 3 kg substrate digested in 5 litre capacity digester. Digestion was
carried out in batch type manner at 15.41% total solids (TS) for eight weeks. The
maximum biogas production (28.97 l/kg) was observed by supplementation of cattle
dung with rice straw at 5 % level. Highest volumetric biogas production of 0.310 l/l/d
with digestion efficiency of 0.201 l/g TS and 0.233 l/g volatile solids (VS) added was
observed on supplementation of cattle dung with rice straw at 5 % level in batch
anaerobic digestion. Maximum degradation of TS (24.56 %) and VS (34.15 %) was
observed on supplementation of cattle dung with rice straw at 5 % level in batch
anaerobic digestion. Under semi-continuous mode with digestion period same as in
batch system, maximum biogas production 30.84 l/kg was found at 5 %
supplementation level of rice straw to cattle dung. This corresponded to volumetric
biogas production of 0.330 l/l/day with digestion efficiency of 0.284 l/g TS, 0.377 l/g
VS. Maximum degradation of 9.77 % TS and 13.60 % VS was observed at 5 % level of
rice straw supplementation in semi-continuous anaerobic digestion. In batch digestion
system N, P and K content of spent substrate at 5 % rice straw supplementation was
1.42, 0.58 and 1.75 % respectively. The N, P and K content of spent substrate under
semi-continuous conditions at 5 % level of rice straw supplementation was 1.61, 0.63
and 1.79 % respectively.
Description
Keywords
Biological phenomena, Bacteria, Organic compounds, Diseases, Pathogens, Acidity, Organic acid salts, Productivity, Food preservation, Enzymes