Efect of feed slurry dilution and total solids on specifc biogas production by anaerobic digestion in batch and semi‑batch reactors

Jeppu, Gautham P and Janardhan, Jayalal and Kaup, Shivakumara and Janardhanan, Anish and Mohammed, Shakeib and Acharya, Sharath (2022) Efect of feed slurry dilution and total solids on specifc biogas production by anaerobic digestion in batch and semi‑batch reactors. Journal of Material Cycles and Waste Management, 24. pp. 97-110. ISSN 1438-4957

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Abstract

Biomass from various sources such as cow dung is a signifcant source of renewable energy (as biogas) in many regions globally, especially in India, Africa, Brazil, and China. However, biogas production from biomass such as cattle dung is a slow, inefcient biochemical process, and the specifc biogas produced per kg of biomass is relatively small. The improve�ment of specifc biogas production efciency using various dilution ratios (and, hence, total solids [TS]) is investigated in this work. A wide range of feed dilution (FD) ratios of cow dung: water (CD: W) was tested in batch biogas digesters with total solids ranging from 1% to 12.5% and FD ratio ranging from 2:1 to 1:20. To further verify the results from the above batch experiments, semi-batch experiments representative of feld-scale biodigesters were conducted. Semi-batch reactors have a steady-state process, unlike batch reactors, which have an unsteady state process. Our results suggested that specifc biogas production (mL/g VS) increased continuously when the total solids decreased from 12.5% to 1% (or when dilution increased). Our experiments also indicate that the commonly used 1:1 feed dilution ratio (TS~10% for cow dung) does not produce the maximum specifc biogas production. The possible reason for this could be that anaerobic digestion at higher total solids is rate limited due to substrate inhibition, mass transfer limitations, and viscous mixing problems that arise at higher total solids concentration. Hence, a higher feed dilution ratio between 1:2 and 1:4 (TS between 4 and 6.7%) is recom�mended for a more efcient biomass utilization of cowdung. Empirical relationships were also developed for variation of specifc biogas yield with the total solids content of the cow dung slurry.

Item Type: Article
Uncontrolled Keywords: Biogas · Total solids · Feed dilution ratio · Cow dung · Anaerobic digestion · Biodigesters · Mixing ratio · Semi�batc
Subjects: Engineering > MIT Manipal > Chemical
Depositing User: MIT Library
Date Deposited: 03 Mar 2022 09:15
Last Modified: 03 Mar 2022 09:15
URI: http://eprints.manipal.edu/id/eprint/158400

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