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HRT dependent performance and bacterial community population of granular hydrogen-producing mixed cultures fed with galactose

Kumar, Gopalakrishnan, Sivagurunathan, Periyasamy, Park, Jeong-Hoon, Park, Jong-Hun, Park, Hee-Deung, Yoon, Jeong-Jun, Kim, Sang-Hyoun
Bioresource technology 2016 v.206 pp. 188-194
Clostridium, bacterial communities, biomass, butyrates, galactose, hydrogen, hydrogen production, lactic acid, mixed culture
The effects of hydraulic retention times (HRTs-6, 3 and 2h) on H2 production, operational stability and bacterial population response in a continuously stirred tank reactor (CSTR) were evaluated using galactose. A peak hydrogen production rate (HPR) of 25.9LH2/L-d was obtained at a 3h HRT with an organic loading rate (OLR) of 120g/L-d, while the maximum hydrogen yield (HY) of 2.21molH2/mol galactose was obtained at a 6h HRT (60ggalactose/L-d). Butyrate was dominant and the lactate concentration increased as HRT decreased, which significantly affected the HY. Biomass concentration (VSS) decreased from 16 to 3g/L at a 2h HRT, leading to failure. A 3h HRT supported the favorable growth of Clostridium species, as indicated by an increase in their populations from 25.4% to 27%, while significantly reducing Bacilli populations from 61.6% to 54.2%, indicating that this was the optimal condition.