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Performance of thermophilic anaerobic digesters using inoculum mixes with enhanced methanogenic diversity
Author(s) -
Ghanimeh Sophia,
ElFadel Mutasem,
Saikaly Pascal E
Publication year - 2018
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.5341
Subject(s) - methanogen , digestate , methanosaeta , propionate , methanosarcina , anaerobic digestion , anaerobic exercise , biogas , food science , methanogenesis , chemistry , biology , bioreactor , pulp and paper industry , methane , botany , biochemistry , ecology , physiology , engineering
BACKGROUND Various mixes of seeds have been quasi‐randomly selected to startup anaerobic digesters. In contrast, this study examines the impact of inoculating thermophilic anaerobic digesters with a designed mix of non‐acclimated seeds based on their methanogen composition, using quantitative polymerase chain reaction ( QPCR ) of 16S rRNA gene, to achieve high abundance and diversity of methanogens. RESULTS Based on QPCR results, two seed mixes were selected to inoculate two anaerobic digesters: digester (A) was inoculated with a control seed consisting of digestate, manure, and activated sludge; and digester (B) was inoculated with a further methanogen‐enriched seed consisting of the control seed with added compost and leachate. Both seed combinations yielded a balanced microflora that is able to achieve a successful startup. However, upon reaching steady state, digester B exhibited lower propionate levels, resulting in lower volatile fatty acids ( VFAs ) concentration and increased buffering capacity, indicating greater stability. Acetotrophs and hydrogenotrophs were dominated by Methanosarcinaceae and Methanobacteriales , respectively, in both digesters, exhibiting an average ratio of 66‐to‐34% in A and 76‐to‐24% in B during steady‐state. CONCLUSION The inoculation strategy in digester B resulted in improved stability, lower propionate concentration and 10% higher relative abundance of acetotrophs. © 2017 Society of Chemical Industry