Producing desulfurized biogas through removal of sulfate in the first‐stage of a two‐stage anaerobic digestion

ABSTRACT In the present work, a two‐stage anaerobic digestion system (TSADS) was newly designed to produce biogas with a greatly reduced H2S content. The role of first (sulfidogenic)‐stage digester was not only acidogenesis but also sulfidogenesis (sulfate reduction to H2S), which would minimize the...

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Published in:Biotechnology and bioengineering 2017-05, Vol.114 (5), p.970-979
Main Authors: Yun, Yeo‐Myeong, Sung, Shihwu, Shin, Hang‐Sik, Han, Jong‐In, Kim, Hyun‐Woo, Kim, Dong‐Hoon
Format: Article
Language:English
Subjects:
Anaerobic digestion
Anaerobiosis
Bioengineering
Biofuels
Biogas
Biological Oxygen Demand Analysis
Bioreactors - microbiology
Biotechnology
Desulfovibrio
Desulfovibrio - metabolism
desulfurized biogas production
Desulfurizing
Digesters
H2S
microbial community analysis
organic wastes
Sewage - microbiology
sulfate reducing bacteria
Sulfates
Sulfates - analysis
Sulfates - isolation & purification
Sulfates - metabolism
two‐stage anaerobic digestion system
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Summary:ABSTRACT In the present work, a two‐stage anaerobic digestion system (TSADS) was newly designed to produce biogas with a greatly reduced H2S content. The role of first (sulfidogenic)‐stage digester was not only acidogenesis but also sulfidogenesis (sulfate reduction to H2S), which would minimize the input of H2S‐producing source in the followed second (methanogenic)‐stage digester. For the coexistence of acidogens and sulfate reducing bacteria (SRB) in the sulfidogenic‐stage digester, it was found that pH played a crucial role. The acidogenic activity was not affected within a pH range of 4.5–6.0, while it was important to maintain a pH at 5.5 to achieve a sulfate removal efficiency over 70%. The highest sulfate removal attained was 78% at a hydraulic retention time (HRT) of 5 h at pH 5.5 ± 0.1. The H2S content in the biogas produced in the conventional single‐stage digester (SSAD), used as a control, reached 1,650 ± 25 ppmv. In contrast, the biogas produced in the methanogenic‐stage digester of the developed process had an H2S content of 200 ± 15 ppmv. Microbial analysis, done by the next generation sequencing technique, clearly showed the changes in community under different operating conditions. Desulfovibrio bastinii (4.9%) played a key role in sulfate removal in the sulfidogenic‐stage of the TSADS owing to its characteristics of a short doubling time and growth in an acidic environment. Biotechnol. Bioeng. 2017;114: 970–979. © 2016 Wiley Periodicals, Inc. A two‐stage anaerobic digestion system was successfully designed to remove 78% of influent sulfate in the sulfidogeneic‐stage digester and obtain high‐purity desulfurized biogas with 200 ± 15 ppmv H2S in the methanogenic‐stage digester. This was linked to the increased population of Desulfovibrio bastinii playing a key role in sulfate removal in the sulfidogenic‐stage of the TSADS. The produced biogas can be directly utilized for electricity or heat generation without a post‐H2S removal process.
ISSN:0006-3592
1097-0290
DOI:10.1002/bit.26233