BIOHYDROGEN PRODUCTION FROM RUMINAL CONTENTS
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Date
2021
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Abstract
Hydrogen gas is a promising alternative for fossil fuel at the current time due
to the advantages that is environment friendly, it can be derived from renewable
sources and it has high energy efficiency. In the present study, hydrogen gas was
producedin a biological way by using rumen fluid of cattle collected from slaughter
house by dark fermentation of rumen fluid and Microbial Electrolysis Cell (MEC)
process. Integration of both dark fermentation and MEC was also carried out.
Dark fermentation of rumen fluid was carried out in 100 ml air tight serum
bottles using rumen fluid as the substrate and microorganisms present in the rumen
fluid as inoculum and the production of biohydrogen was confirmed by gas
chromatography with Thermal conductivity detector (GC-TCD). The dark
fermentation parameters such as pH, substrates and micronutrient concentrations
were optimized. The pH 4, 5, 6, 7 and 8 were used for dark fermentation of rumen
fluid and it was found that pH 6 produced higher biohydrogen when compared to
other pH. Substrates such as 1% rice bran, 1% powdered potato peel and 1%
powdered tapioca peel were used as added substrates to rumen fluid for dark
fermentation and it was found that 1% rice bran produced higher biohydrogen. The
micronutrients used were O.25M, 0.5M, 0.75M and IM concentrations of Ferrous
sulphate. Magnesium sulpahte and Potassium sulphate. It was found that in all the
three mucronutrients, 0,5M concentration produced higher biohydrogen. Rumen
fluid collected from slaughter house was used for isolation of biohydrogen
producing microorganisms and four different biohydrogen producing bacteria were
isolated, characterized and the production of biohydrogen was also confirmed using
the individual bacteria in dark fermentation. The rumen fluid after dark fermentation
was also given for metagenomic analysis to find out the phylum, genus and species
abundance in the rumen fluid.
The Microbial electrolysis cell (MEC) was designed and made for the
biohydrogen production. The parameters such as pH, salt-bridge, catholyte,
electrodes and substrates were optimized for the production of biohydrogen. Among
the pH 4, 5, 6, 7 and 8, the highest amount of biohydrogen production was obtained
in pH 6. 0.8% and 1% of agarose and agar-agar were used as salt-bridge in the MEC
and the highest biohydrogen production was obtained in MEC with 0.8% agarose.
The electrodes used were carbons rods and graphite plates where the MEC with
graphite plates as the electrode showed higher biohydrogen production. Sodium
chloride in different concentrations such as 0.25M, 0.5M, 0.75M and IM were used
and it was found that 0.5M Sodium chloride produced highest amount of
biohydrogen in MEC. The substrates added to the rumen fluid in the anode chamber
were 1% rice bran, 1% powdered potato peel and 1% powdered tapioca peel and the
highest amount of biohydrogen production was obtained in the MEC with 1% rice
bran.The integration of dark fermentation and MEC was carried out for an enhanced
amount of biohydrogen production. The total amount of biohydrogen produced was
calculated from the individual amount of biohydrogen produced by dark
fermentation and MEC. The quantity of biohydrogenproduced were statistically
analysed and the obtained p value is less than 0.005 (p<0.005) which shows that
the quantity of biohydrogen produced with different pH and substrates were
statistically significant.