Development of microbial inoculum for efficient biogas production
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Date
2016
Authors
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Journal ISSN
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Publisher
CCSHAU
Abstract
The ever increasing cost of fossil fuels and its attendant pollution menace has provided the
pedigree to consider alternative sources of energy. Biogas is a well established fuel that can supplement
as an energy source for cooking and lighting source in developing countries. There is a need to improve
and also increase the efficiency of biogas production. Therefore, in the present investigation, compost,
paddy soil, landfill waste and kitchen waste were used to develop the microbial inoculum for the
enhancement of biogas production from cattle dung. Six digesters were set up containing biogas slurry
@10%, biogas slurry @ 20%, compost @10%, paddy soil @ 10%, landfill waste @10 % and kitchen
waste @10% along with cattle dung (3 kg). The maximum biogas production (57.6 litres), and
maximum degradation of TS (28.8%) and VS (18.6%) was observed on supplementation of cattle dung
with kitchen waste @ 10% on dry weight basis in batch anaerobic digestion. Subsequently, various
combinations of these inocula with cattle dung were made for determining their effect on biogas
production under batch and semi-continuous anaerobic digestion conditions and 14 digesters were set
up. Maximum biogas production (114.2 litres) was observed in digester, D14(Cattle dung (3kg) +
kitchen waste @5%+ compost @ 5% + landfill waste @ 5%+ paddy soil @ 5%) during batch
anaerobic digestion. In semi continuous mode with digestion period of eight weeks, the biogas
production increased upto seventh week and maximum biogas production (144.2 litres) was observed
in digester, D14 followed by digester, D2 (cattle dung (3kg) +biogas slurry@ 20%) in which biogas
production was 130.5 litres. The dehydrogenase activity (1993.0 µg TPF/g sample/24 h) and cellulase
activity (259.4 µg glucose/ g sample/24 h) was observed at the end of 8
th
week in digester, D14.
Ligninolytic activity was found to be maximum in digester, D14 at the end of 4
th
week having zone
index of 2.80 during batch anaerobic digestion and 3.01 during semi-continuous digestion. In modified
Janta Biogas plant, the biogas production was found to be more in J2 plant where cattle dung was
supplemented with kitchen waste @5%, compost @ 5%, landfill waste @ 5% and paddy soil @ 5% as
compared to J1 plant (cattle dung alone). CLPP analysis showed that microbial diversity in digester,
D1(cattle dung + biogas slurry @ 10%) is entirely different from that in digester, D2 (cattle dung +
biogas slurry @ 20%) and D14(cattle dung (3kg) + kitchen waste @5%+ compost @ 5% + landfill
waste @ 5%+ paddy soil @ 5%). Digester D2 and D14 showed similarity in microbial diversity. Thus,
cattle dung along with kitchen waste @ 5%, compost @ 5%, landfill waste @ 5% and paddy soil @ 5%
or cattle dung along with biogas slurry @ 20% could be exploited for efficient biogas production
Description
Keywords
Biogas, Cattle dung, Inoculum, Anaerobic digestion, CLPP