Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1282966 | International Journal of Hydrogen Energy | 2010 | 12 Pages |
Abstract
This study investigated the impact of six organic loading rates (OLR) ranging from 6.5Â gCOD/L-d to 206Â gCOD/L-d on the performance of a novel integrated biohydrogen reactor clarifier systems (IBRCSs) comprised a continuously stirred reactor (CSTR) for biological hydrogen production, followed by an uncovered gravity settler for decoupling of solids retention time (SRT) from hydraulic retention time (HRT). The system was able to maintain a high molar hydrogen yield of 2.8Â mol H2/mol glucose at OLR ranging from 6.5 to 103Â gCOD/L-d, but dropped precipitously to approximately 1.2 and 1.1Â mol H2/mol glucose for the OLRs of 154 and 206Â gCOD/L-d, respectively. The optimum OLR at HRT of 8Â h for maximizing both hydrogen molar yield and volumetric hydrogen production was 103Â gCOD/L-d. A positive statistical correlation was observed between the molar hydrogen production and the molar acetate-to-butyrate ratio. Biomass yield correlated negatively with hydrogen yield, although not linearly. Analyzing the food-to-microorganisms (F/M) data in this study and others revealed that, both molar hydrogen yields and biomass specific hydrogen rates peaked at 2.8Â mol H2/mol glucose and 2.3Â L/gVSS-d at F/M ratios ranging from 4.4 to 6.4Â gCOD/gVSS-d. Microbial community analysis for OLRs of 6.5 and 25.7Â gCOD/L-d showed the predominance of hydrogen producers such as Clostridium acetobutyricum, Klebsiella pneumonia, Clostridium butyricum, Clostridium pasteurianum. While at extremely high OLRs of 154 and 206Â gCOD/L-d, a microbial shift was clearly evident due to the coexistence of the non-hydrogen producers such as Lactococcus sp. and Pseudomonas sp.
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Authors
Hisham Hafez, George Nakhla, M. Hesham El. Naggar, Elsayed Elbeshbishy, Bita Baghchehsaraee,