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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

Kinetic characterizations of dark and photo-fermentative bacteria. (a) Cell growth kinetics; (b) H2 production kinetics; (c) acetate production and consumption kinetics; (d) pH change during fermentation.
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Fig1: Kinetic characterizations of dark and photo-fermentative bacteria. (a) Cell growth kinetics; (b) H2 production kinetics; (c) acetate production and consumption kinetics; (d) pH change during fermentation.

Mentions: The kinetics of cell growth, hydrogen production, acetic acid production, and consumption of E. harbinese B49 and R. faecalis RLD-53 were investigated under their own optimal conditions [26,27] with a logistic model, modified Gompertz equation, and modified Richards model, respectively (Figure 1), and the main kinetic parameters are summarized in Table 1. At a glucose concentration of 10 g/L, the maximum hydrogen production rate () of E. harbinense B49 was 163.98 ml/L/h, which was more than five times that of R. faecalis RLD-53. 49.84 mmol/L of acetate was produced by E. harbinense B49 with a maximum production rate (RpHAc) of 2.73 mmol/L/h, while the maximum acetate degradation rate (RdHAc) by R. faecalis RLD-53 was only 0.38 mmol/L/h at an acetate concentration of 50 mmol/L (Table 1). The results showed that the maximum acetate production rate by E. harbinense B49 was about seven times the degradation rate by R. faecalis RLD-53. In addition, the specific growth rate (kc) of E. harbinense B49 was 0.31 h−1, which indicated that E. harbinense B49 grows more slowly than Clostridium butyricum CGS5 with a specific growth rate of 0.77 h−1 [20] and Enterobacter cloacae IIT-BT 08 with a specific growth rate of 1.12 h−1 [21]. The specific growth rate (kc) of R. faecalis RLD-53 was 0.06 h−1, which was much faster than Rhodobacter capsulatus DSM 1710 with a specific growth rate of 0.025 h−1 [22], but slightly slower than Rhodopseudomonas palustris with a specific growth rate of 0.074 h−1 [24]. The results also showed that the specific growth rate of E. harbinense B49 was about five times faster than that of R. faecalis RLD-53 (Table 1). Therefore, the imbalance of metabolic and cell growth rate between the two types of bacteria could exacerbate the accumulation of acetic acid, which would decrease the pH and subsequently inhibit R. faecalis RLD-53. In the IDPFR, a membrane with pore size 0.22 μm was used to divide the reactor into two separate reaction chambers. In the dark chamber, complex waste biomass was converted by E. harbinense B49 into hydrogen, carbon dioxide, ethanol, and acetate. Acetate could diffuse through the membrane into the photo chamber. In the photo chamber, acetate from the dark chamber was utilized by R. faecalis RLD-53 to produce hydrogen and carbon dioxide. By increasing the working volume of the photo chamber, more R. faecalis RLD-53 could couple with E. harbinense B49, and the organic acids produced by E. harbinense B49 could be expected to be consumed completely by R. faecalis RLD-53 without accumulation.Figure 1


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)

Kinetic characterizations of dark and photo-fermentative bacteria. (a) Cell growth kinetics; (b) H2 production kinetics; (c) acetate production and consumption kinetics; (d) pH change during fermentation.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig1: Kinetic characterizations of dark and photo-fermentative bacteria. (a) Cell growth kinetics; (b) H2 production kinetics; (c) acetate production and consumption kinetics; (d) pH change during fermentation.
Mentions: The kinetics of cell growth, hydrogen production, acetic acid production, and consumption of E. harbinese B49 and R. faecalis RLD-53 were investigated under their own optimal conditions [26,27] with a logistic model, modified Gompertz equation, and modified Richards model, respectively (Figure 1), and the main kinetic parameters are summarized in Table 1. At a glucose concentration of 10 g/L, the maximum hydrogen production rate () of E. harbinense B49 was 163.98 ml/L/h, which was more than five times that of R. faecalis RLD-53. 49.84 mmol/L of acetate was produced by E. harbinense B49 with a maximum production rate (RpHAc) of 2.73 mmol/L/h, while the maximum acetate degradation rate (RdHAc) by R. faecalis RLD-53 was only 0.38 mmol/L/h at an acetate concentration of 50 mmol/L (Table 1). The results showed that the maximum acetate production rate by E. harbinense B49 was about seven times the degradation rate by R. faecalis RLD-53. In addition, the specific growth rate (kc) of E. harbinense B49 was 0.31 h−1, which indicated that E. harbinense B49 grows more slowly than Clostridium butyricum CGS5 with a specific growth rate of 0.77 h−1 [20] and Enterobacter cloacae IIT-BT 08 with a specific growth rate of 1.12 h−1 [21]. The specific growth rate (kc) of R. faecalis RLD-53 was 0.06 h−1, which was much faster than Rhodobacter capsulatus DSM 1710 with a specific growth rate of 0.025 h−1 [22], but slightly slower than Rhodopseudomonas palustris with a specific growth rate of 0.074 h−1 [24]. The results also showed that the specific growth rate of E. harbinense B49 was about five times faster than that of R. faecalis RLD-53 (Table 1). Therefore, the imbalance of metabolic and cell growth rate between the two types of bacteria could exacerbate the accumulation of acetic acid, which would decrease the pH and subsequently inhibit R. faecalis RLD-53. In the IDPFR, a membrane with pore size 0.22 μm was used to divide the reactor into two separate reaction chambers. In the dark chamber, complex waste biomass was converted by E. harbinense B49 into hydrogen, carbon dioxide, ethanol, and acetate. Acetate could diffuse through the membrane into the photo chamber. In the photo chamber, acetate from the dark chamber was utilized by R. faecalis RLD-53 to produce hydrogen and carbon dioxide. By increasing the working volume of the photo chamber, more R. faecalis RLD-53 could couple with E. harbinense B49, and the organic acids produced by E. harbinense B49 could be expected to be consumed completely by R. faecalis RLD-53 without accumulation.Figure 1

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