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Kim D.-H.,Korea Institute of Energy Research | Jang S.,Korea Institute of Energy Research | Jang S.,Korean University of Science and Technology | Yun Y.-M.,KAIST | And 6 more authors.
International Journal of Hydrogen Energy | Year: 2014

This work presents the effect of acid-pretreatment on H2 fermentation of food waste with detailed microbial information by next generation sequencing. The pretreated food waste at pH 1.0-4.0 was cultivated under mesophilic conditions without external inoculum addition. From the food waste acid-pretreated at pH 1-3, H2 yields in the range of 1.37-1.74 mol H2/mol hexoseadded were achieved, attaining the highest value at pH 2. Clostridium sp. such as Clostridium acetobutylicum ATCC 824 and Clostridium perfringens occupied more than 70% of total number of sequences at pH 1-3. On the other hand, in the control (no pretreatment) and at pH 4, lactic acid bacteria such as Lactobacillus and Streptococcus were found to be the dominant genus (>90% of total number of sequences), resulting in a low H2 yield. In addition, the effect of substrate concentration on H2 fermentation was investigated, and the maximum H2 productivity was estimated to be 27.2 L H2/L/d by Andrew's model. © 2014 Hydrogen Energy Publications, LLC.


Moon C.,Korea Institute of Energy Research | Jang S.,Korea Institute of Energy Research | Yun Y.-M.,KAIST | Lee M.-K.,Korea Institute of Energy Research | And 4 more authors.
Bioresource Technology | Year: 2014

pH, known as the most important parameter in H2 fermentation, cannot be precisely controlled in a scaled-up fermenter as in a lab fermenter. In the preset work, to assess the effect of pH control accuracy on H2 fermentation, the pH was controlled at 6.0±0.1, 6.0±0.3, 6.0±0.5, 6.0±0.7, and 6.0±0.9 during batch fermentation of food waste. Up to deviation of ±0.3, a high H2 yield of 1.67-1.73molH2/mol hexoseadded was attained with producing butyrate as a major metabolite (>70% of total organic acids produced). A huge drop of H2 production, however, was observed at deviation >±0.5 with lowered substrate utilization and increased production of lactate. Next generation sequencing results showed that Clostridium was found to be the dominant genus (76.4% of total number of sequences) at deviation of ±0.1, whereas the dominant genus was changed to lactic acid bacteria such as Streptococcus and Lactobacillus with increase of deviation value. © 2014 Elsevier Ltd.


Kim D.-H.,Korea Institute of Energy Research | Jang S.,Korea Institute of Energy Research | Yun Y.-M.,KAIST | Lee M.-K.,Korea Institute of Energy Research | And 4 more authors.
International Journal of Hydrogen Energy | Year: 2014

This work presents the effect of acid-pretreatment on H2 fermentation of food waste with detailed microbial information by next generation sequencing. The pretreated food waste at pH 1.0-4.0 was cultivated under mesophilic conditions without external inoculum addition. From the food waste acid-pretreated at pH 1-3, H2 yields in the range of 1.37-1.74 mol H2/mol hexoseadded were achieved, attaining the highest value at pH 2. Clostridium sp. such as Clostridium acetobutylicum ATCC 824 and Clostridium perfringens occupied more than 70% of total number of sequences at pH 1-3. On the other hand, in the control (no pretreatment) and at pH 4, lactic acid bacteria such as Lactobacillus and Streptococcus were found to be the dominant genus (>90% of total number of sequences), resulting in a low H2 yield. In addition, the effect of substrate concentration on H2 fermentation was investigated, and the maximum H2 productivity was estimated to be 27.2 L H2/L/d by Andrew's model. © 2014 Hydrogen Energy Publications, LLC.


Jang S.,Korea Institute of Energy Research | Jang S.,Korean University of Science and Technology | Kim D.-H.,Inha University | Yun Y.-M.,KAIST | And 6 more authors.
Bioresource Technology | Year: 2015

In the study, at first, batch tests were performed to investigate the effect of alkali-shock on H2 production from food waste (FW). After alkali-pretreatment of FW at pH 9.0-13.0, the FW was cultivated under mesophilic condition at pH 6.0 for 30h without external inoculum addition. The amount of H2 production from FW pretreated at pH 11.0 and 12.0 was higher than that achieved in other pretreatment pH. The main metabolite was butyrate, and Clostridium were dominant at pH 11.0 and 12.0. Meanwhile, lactate was the main metabolite with Enterococcus and Streptococcus being the dominant genus at other pretreatment pH. When the batch process was switched to a continuous mode, H2 production was significantly dropped due to the increased activity of H2-consumers. The reliability of alkali-pretreatment at pH 11.0 was proven by repeating the scale-up batch process, recording 1.57±0.11molH2/mol hexoseadded (17±2LH2/kg FW) and 4.39±0.32LH2/L/d. © 2015.


Moon C.,Korea Advanced Institute of Science and Technology | Jang S.,Korea Advanced Institute of Science and Technology | Jang S.,KAIST | Yun Y.-M.,Korea District Heating Corporation R and D Institute | And 6 more authors.
Bioresource Technology | Year: 2015

pH, known as the most important parameter in H2 fermentation, cannot be precisely controlled in a scaled-up fermenter as in a lab fermenter. In the preset work, to assess the effect of pH control accuracy on H2 fermentation, the pH was controlled at 6.0±0.1, 6.0±0.3, 6.0±0.5, 6.0±0.7, and 6.0±0.9 during batch fermentation of food waste. Up to deviation of ±0.3, a high H2 yield of 1.67-1.73molH2/mol hexoseadded was attained with producing butyrate as a major metabolite (70% of total organic acids produced). A huge drop of H2 production, however, was observed at deviation 0.5 with lowered substrate utilization and increased production of lactate. Next generation sequencing results showed that Clostridium was found to be the dominant genus (76.4% of total number of sequences) at deviation of ±0.1, whereas the dominant genus was changed to lactic acid bacteria such as Streptococcus and Lactobacillus with increase of deviation value. © 2014 Elsevier Ltd.

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