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Simultaneous hydrogen and ethanol production from cascade utilization of mono-substrate in integrated dark and photo-fermentative reactor.

Liu BF, Xie GJ, Wang RQ, Xing DF, Ding J, Zhou X, Ren HY, Ma C, Ren NQ - Biotechnol Biofuels (2015)

Bottom Line: Moreover, simultaneous hydrogen and ethanol production were achieved by coupling E. harbinese B49 and R. faecalis RLD-53 in the IDPFR.According to stoichiometry, the hydrogen and ethanol production efficiencies were 82.67% and 82.19%, respectively.Therefore, IDPFR was an effective strategy for coupling DFB and PFB to fulfill efficient energy recovery from waste biomass.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090 China.

ABSTRACT

Background: Integrating hydrogen-producing bacteria with complementary capabilities, dark-fermentative bacteria (DFB) and photo-fermentative bacteria (PFB), is a promising way to completely recover bioenergy from waste biomass. However, the current coupled models always suffer from complicated pretreatment of the effluent from dark-fermentation or imbalance between dark and photo-fermentation, respectively. In this work, an integrated dark and photo-fermentative reactor (IDPFR) was developed to completely convert an organic substrate into bioenergy.

Results: In the IDPFR, Ethanoligenens harbinese B49 and Rhodopseudomonas faecalis RLD-53 were separated by a membrane into dark and photo chambers, while the acetate produced by E. harbinese B49 in the dark chamber could freely pass through the membrane into the photo chamber and serve as a carbon source for R. faecalis RLD-53. The hydrogen yield increased with increasing working volume of the photo chamber, and reached 3.38 mol H2/mol glucose at the dark-to-photo chamber ratio of 1:4. Hydrogen production by the IDPFR was also significantly affected by phosphate buffer concentration, glucose concentration, and ratio of dark-photo bacteria. The maximum hydrogen yield (4.96 mol H2/mol glucose) was obtained at a phosphate buffer concentration of 20 mmol/L, a glucose concentration of 8 g/L, and a ratio of dark to photo bacteria of 1:20. As the glucose and acetate were used up by E. harbinese B49 and R. faecalis RLD-53, ethanol produced by E. harbinese B49 was the sole end-product in the effluent from the IDPFR, and the ethanol concentration was 36.53 mmol/L with an ethanol yield of 0.82 mol ethanol/mol glucose.

Conclusions: The results indicated that the IDPFR not only circumvented complex pretreatments on the effluent in the two-stage process, but also overcame the imbalance of growth and metabolic rate between DFB and PFB in the co-culture process, and effectively enhanced cooperation between E. harbinense B49 and R. faecalis RLD-53. Moreover, simultaneous hydrogen and ethanol production were achieved by coupling E. harbinese B49 and R. faecalis RLD-53 in the IDPFR. According to stoichiometry, the hydrogen and ethanol production efficiencies were 82.67% and 82.19%, respectively. Therefore, IDPFR was an effective strategy for coupling DFB and PFB to fulfill efficient energy recovery from waste biomass.

No MeSH data available.


Related in: MedlinePlus

Hydrogen production and acetate accumulation in IDPFR at different phosphate concentrations. (a) 10 mmol/L; (b) 20 mmol/L; (c), 30 mmol/L.
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Fig3: Hydrogen production and acetate accumulation in IDPFR at different phosphate concentrations. (a) 10 mmol/L; (b) 20 mmol/L; (c), 30 mmol/L.

Mentions: As shown in Figure 3, at a phosphate concentration of 10 mmol/L, the total hydrogen production was 4,199.14 ml/L and the hydrogen yield reached 3.37 mol H2/mol glucose. When the phosphate concentration increased to 20 mmol/L, the total hydrogen production was 4,766.90 ml/L and the hydrogen yield reached 3.83 mol H2/mol glucose. The result indicated that the increase of phosphate concentration from 10 to 20 mmol/L was conducive to hydrogen production by dark and photo-fermentation. However, with a further increase of phosphate concentration to 30 mmol/L, hydrogen production by R. faecalis RLD-53 in the photo chamber decreased sharply to 1,893.93 ml/L, and the hydrogen yield was only 3.18 mol H2/mol glucose. The high concentration of phosphate also inhibited hydrogen production by R. faecalis RLD-53, and therefore decreased hydrogen production by the IDPFR. With an increase of phosphate concentration from 10 mmol/L to 20 mmol/L, acetate concentration in the end product decreased from 17.03 to 13.04 mmol/L. Consequently, the end pH of the IDPFR increased from 5.8 to 6.2, which approximated the optimum pH (6.5-7.5) for R. faecalis RLD-53. However, when the phosphate concentration was further increased to 30 mmol/L, the acetate concentration significantly increased to 20.78 mmol/L, probably due to inhibition of cell growth and hydrogen production activities resulting from the high phosphate concentration. As a result, acetate accumulation increased and therefore the end pH decreased to 5.6, which is unfavorable for PFB. Therefore, the maximum hydrogen yield was obtained at a phosphate concentration of 20 mmol/L.Figure 3


Simultaneous hydrogen and ethanol production from cascade utilization of mono-substrate in integrated dark and photo-fermentative reactor.

Liu BF, Xie GJ, Wang RQ, Xing DF, Ding J, Zhou X, Ren HY, Ma C, Ren NQ - Biotechnol Biofuels (2015)

Hydrogen production and acetate accumulation in IDPFR at different phosphate concentrations. (a) 10 mmol/L; (b) 20 mmol/L; (c), 30 mmol/L.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4308915&req=5

Fig3: Hydrogen production and acetate accumulation in IDPFR at different phosphate concentrations. (a) 10 mmol/L; (b) 20 mmol/L; (c), 30 mmol/L.
Mentions: As shown in Figure 3, at a phosphate concentration of 10 mmol/L, the total hydrogen production was 4,199.14 ml/L and the hydrogen yield reached 3.37 mol H2/mol glucose. When the phosphate concentration increased to 20 mmol/L, the total hydrogen production was 4,766.90 ml/L and the hydrogen yield reached 3.83 mol H2/mol glucose. The result indicated that the increase of phosphate concentration from 10 to 20 mmol/L was conducive to hydrogen production by dark and photo-fermentation. However, with a further increase of phosphate concentration to 30 mmol/L, hydrogen production by R. faecalis RLD-53 in the photo chamber decreased sharply to 1,893.93 ml/L, and the hydrogen yield was only 3.18 mol H2/mol glucose. The high concentration of phosphate also inhibited hydrogen production by R. faecalis RLD-53, and therefore decreased hydrogen production by the IDPFR. With an increase of phosphate concentration from 10 mmol/L to 20 mmol/L, acetate concentration in the end product decreased from 17.03 to 13.04 mmol/L. Consequently, the end pH of the IDPFR increased from 5.8 to 6.2, which approximated the optimum pH (6.5-7.5) for R. faecalis RLD-53. However, when the phosphate concentration was further increased to 30 mmol/L, the acetate concentration significantly increased to 20.78 mmol/L, probably due to inhibition of cell growth and hydrogen production activities resulting from the high phosphate concentration. As a result, acetate accumulation increased and therefore the end pH decreased to 5.6, which is unfavorable for PFB. Therefore, the maximum hydrogen yield was obtained at a phosphate concentration of 20 mmol/L.Figure 3

Bottom Line: Moreover, simultaneous hydrogen and ethanol production were achieved by coupling E. harbinese B49 and R. faecalis RLD-53 in the IDPFR.According to stoichiometry, the hydrogen and ethanol production efficiencies were 82.67% and 82.19%, respectively.Therefore, IDPFR was an effective strategy for coupling DFB and PFB to fulfill efficient energy recovery from waste biomass.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090 China.

ABSTRACT

Background: Integrating hydrogen-producing bacteria with complementary capabilities, dark-fermentative bacteria (DFB) and photo-fermentative bacteria (PFB), is a promising way to completely recover bioenergy from waste biomass. However, the current coupled models always suffer from complicated pretreatment of the effluent from dark-fermentation or imbalance between dark and photo-fermentation, respectively. In this work, an integrated dark and photo-fermentative reactor (IDPFR) was developed to completely convert an organic substrate into bioenergy.

Results: In the IDPFR, Ethanoligenens harbinese B49 and Rhodopseudomonas faecalis RLD-53 were separated by a membrane into dark and photo chambers, while the acetate produced by E. harbinese B49 in the dark chamber could freely pass through the membrane into the photo chamber and serve as a carbon source for R. faecalis RLD-53. The hydrogen yield increased with increasing working volume of the photo chamber, and reached 3.38 mol H2/mol glucose at the dark-to-photo chamber ratio of 1:4. Hydrogen production by the IDPFR was also significantly affected by phosphate buffer concentration, glucose concentration, and ratio of dark-photo bacteria. The maximum hydrogen yield (4.96 mol H2/mol glucose) was obtained at a phosphate buffer concentration of 20 mmol/L, a glucose concentration of 8 g/L, and a ratio of dark to photo bacteria of 1:20. As the glucose and acetate were used up by E. harbinese B49 and R. faecalis RLD-53, ethanol produced by E. harbinese B49 was the sole end-product in the effluent from the IDPFR, and the ethanol concentration was 36.53 mmol/L with an ethanol yield of 0.82 mol ethanol/mol glucose.

Conclusions: The results indicated that the IDPFR not only circumvented complex pretreatments on the effluent in the two-stage process, but also overcame the imbalance of growth and metabolic rate between DFB and PFB in the co-culture process, and effectively enhanced cooperation between E. harbinense B49 and R. faecalis RLD-53. Moreover, simultaneous hydrogen and ethanol production were achieved by coupling E. harbinese B49 and R. faecalis RLD-53 in the IDPFR. According to stoichiometry, the hydrogen and ethanol production efficiencies were 82.67% and 82.19%, respectively. Therefore, IDPFR was an effective strategy for coupling DFB and PFB to fulfill efficient energy recovery from waste biomass.

No MeSH data available.


Related in: MedlinePlus