TY - JOUR
T1 - The effect of pH on the production of biohydrogen by clostridia
T2 - Thermodynamic and metabolic considerations
AU - Liu, I. Chun
AU - Whang, Liang Ming
AU - Ren, Wei Jie
AU - Lin, Pei Ying
N1 - Funding Information:
The authors would like to acknowledge the financial support from National Science Council of Taiwan under Grant NSC 98-3114-E-006-013 . We thank Dr. J.S. Chang and Dr. I.C. Tseng of the National Cheng Kung University and Dr. C.C. Huang of the National Chung Hsing University for the gifts of Clostridium species used in this study.
PY - 2011/1
Y1 - 2011/1
N2 - This study evaluates the effect of pH (4-7) on fermentative biohydrogen production by utilizing three isolated Clostridium species. Fermentative batch experiments show that the maximum hydrogen yield for Clostridium butyricum CGS2 (1.77 mmol/mmol glucose) is achieved at pH 6, whereas a high hydrogen production with Clostridium beijerinckii L9 (1.72 mmol/mmol glucose) and Clostridium tyrobutyricum FYa102 (1.83 mmol/mmol glucose) could be achieved under uncontrolled pH conditions (initial pH of 6.4-6.6 and final pH of 4-4.2). Low hydrogen yields (0-0.6 mmol/mmol glucose) observed at pH 4 are due likely to inhibitory effects on the microbial growth, although a low pH can be thermodynamically favorable for hydrogen production. The low hydrogen yields (0.12-0.64 mmol/mmol glucose) observed at pH 7 are attributed not only to thermodynamically unfavorable, but also metabolically unfavorable for hydrogen production. The relatively high levels of lactate, propionate, or formate observed at pH 7 reflect presumably the high enzymatic activities responsible for their production, together with the low hydrogenase activity, resulting in a low hydrogen production. A correlation analysis of the data from present and previous studies on biohydrogen production with pure Clostridium cultures and mixed microflora indicates a close relation between the hydrogen yield (YH2) and the (YH2)/(2(YHAc+YHBu)) ratio, with the observed correlation coefficient (0.787) higher than that (0.175) between YH2 and the molar ratio of butyrate to acetate (B/A). Based on the (YH2)/(2(YHAc+YHBu)) ratios observed at different pHs, a control of pH at 5.5-6.8 would seem to be an effective means to enhance the fermentative biohydrogen production.
AB - This study evaluates the effect of pH (4-7) on fermentative biohydrogen production by utilizing three isolated Clostridium species. Fermentative batch experiments show that the maximum hydrogen yield for Clostridium butyricum CGS2 (1.77 mmol/mmol glucose) is achieved at pH 6, whereas a high hydrogen production with Clostridium beijerinckii L9 (1.72 mmol/mmol glucose) and Clostridium tyrobutyricum FYa102 (1.83 mmol/mmol glucose) could be achieved under uncontrolled pH conditions (initial pH of 6.4-6.6 and final pH of 4-4.2). Low hydrogen yields (0-0.6 mmol/mmol glucose) observed at pH 4 are due likely to inhibitory effects on the microbial growth, although a low pH can be thermodynamically favorable for hydrogen production. The low hydrogen yields (0.12-0.64 mmol/mmol glucose) observed at pH 7 are attributed not only to thermodynamically unfavorable, but also metabolically unfavorable for hydrogen production. The relatively high levels of lactate, propionate, or formate observed at pH 7 reflect presumably the high enzymatic activities responsible for their production, together with the low hydrogenase activity, resulting in a low hydrogen production. A correlation analysis of the data from present and previous studies on biohydrogen production with pure Clostridium cultures and mixed microflora indicates a close relation between the hydrogen yield (YH2) and the (YH2)/(2(YHAc+YHBu)) ratio, with the observed correlation coefficient (0.787) higher than that (0.175) between YH2 and the molar ratio of butyrate to acetate (B/A). Based on the (YH2)/(2(YHAc+YHBu)) ratios observed at different pHs, a control of pH at 5.5-6.8 would seem to be an effective means to enhance the fermentative biohydrogen production.
UR - http://www.scopus.com/inward/record.url?scp=79251643069&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79251643069&partnerID=8YFLogxK
U2 - 10.1016/j.ijhydene.2010.10.045
DO - 10.1016/j.ijhydene.2010.10.045
M3 - Article
AN - SCOPUS:79251643069
VL - 36
SP - 439
EP - 449
JO - International Journal of Hydrogen Energy
JF - International Journal of Hydrogen Energy
SN - 0360-3199
IS - 1
ER -