Integration of Electrochemical cell for Enhancement of Biogas production from cattle manure and molecular characterization of isolated microflora
Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Department of Biotechnology
Abstract
Nepal is a developing country where most of the population is still living in rural
areas. A continuous supply of cooking gas as Liquid Petroleum Gas is difficult and
expensive. So biogas is a good alternative for them. Biogas production is affected
by several factors; temperature is an important factor to be considered during
anaerobic digestion (AD) for effective degradation of organic waste. Though most
of the rural areas’ of Nepal have assembled biogas plant, due to the climatic
variation, during winter season, production of biogas is less. Enhancement of
biogas production can be done by various methods. Among them integration of
microbial electrochemical cell (MEC) system in existing AD is a new and
innovative technique where a small voltage of electricity supplied to reduce CO2
produced in digester to methane with help of methanogens as a biocatalyst.
AD
using cow dung is cheap and clean method of production of biogas which help to
reduce serious environmental and health problems. During this work, integration
of microbial electrochemical cell (MEC) system in conventional anaerobic
digester showed reduction percentage was 2.7% and 8% greater in 1 L and 5 L
digester respectively in MEC compared to conventional control setup while
reduction of soluble reducing sugar was 33% and 9% greater in 1 L and 5 L
digester at 15°C compared to control setup. At room temperature (23-29°C),
reduction percentage of COD was about 11% and 18% higher in comparison to
controlled digester. Likewise, reduction percentage of soluble reducing sugar was
32% higher in 1L and 19% higher in 5 L digester compared to the control digester.
Biogas production was enhanced by about 28% compared to control setup even
at temperature of 15°C in both 1 L and 5 L digester. Similarly, enhancement of
biogas in 1 L digester and 5 L digester was 35.18±0.52% and 41.17% respectively
at room temperature. Despite of enhancement, the reaction of microbial
electrochemical cell was done successfully for short period of time which is not
enough for complete digestion of cow dung. Hence, further study on the MEC for
elongated digestion of organic waste and assembly of fed batch system is
necessary. We analyze the change in different parameters for already existing
6000 L biogas plant. There was very negligible change in COD, soluble reducing
sugar as there was a provision of continuous feeding of substrate every day. For
the identification of microorganism, among six isolates 14IN and 18IN showed
significant level of cellulase production while doing hallo zone test with congo
red. PCR product of 16s rRNA of while sequenceing showed the microorganisms
14IN and 18IN were Bacillus licheniformis and Bacillus aerius respectively.
Keywords: Biogas, microbial electrochemical cell, anaerobic digestion, chemical
oxygen demand.
Description
Keywords
Biogas, Microbial electrochemical cell, Anaerobic digestion, Chemical oxygen demand