Hydrogen regulation of acetogenesis from glucose by freely suspended and immobilised acidogenic cells in continuous culture

Fynn, G. H.; Syafila, Mindriany

doi:10.1007/bf01030763

Cited by 21 publications

(5 citation statements)

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“…In the Ðrst case, 67% of the input COD was assumed to be converted to acetate ; this is a typical situation in anaerobic reactors, and its accumulation in the absence of an aceticlastic methanogenic reaction was simulated as per eqn (1). In the second hypothetical case, all the input COD was assumed to be totally fermented to acetate as shown in eqn (2).…”

Section: Discussionmentioning

confidence: 99%

“…From the response of the control reactor, it is clear that the total acids (all VFAs converted to acetate equivalents) were initially below or about what was expected, but after 8 days they were much higher than the "normalÏ digester response, and reached almost 90% of the total input carbon by day 15. This seems to imply that the hydrogen levels in the digester may have been regulated through homoacetogenic reactions11 (either (2) or (3)). In contrast, the acetate concentrations in the membrane reactor were considerably below the control, and lower than the assumed model situation of 67% conversion ( Fig.…”

Section: Discussionmentioning

confidence: 99%

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Stability enhancement of anaerobic digestion through membrane gas extraction under organic shock loads

Voolapalli

Stuckey

1998

J. Chem. Technol. Biotechnol.

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: A novel submerged silicone membrane extraction technique for removing the dissolved gases, and was explored as a method for enhancing CO 2 H 2 , the stability of anaerobic digesters under shock loads. The e †ectiveness of this strategy was demonstrated during a Ðve-fold step increase in the feed concentration from 4 kg m~3 to 20 kg m~3 Chemical Oxygen Demand (COD) to two anaerobic chemostats, a control and a membrane reactor, operating under steady state. Data revealed that membrane extraction of enabled neutral pH values CO 2 to be maintained during the shock, in contrast to the control ; and this appeared to enhance acetate degradation. In addition, while liquid phase hydrogen removal was only partially successful due to a bioÐlm building up on the membrane, it also appeared to enhance the rate of volatile fatty acid degradation, and hence improved reactor stability. Floc sizes were monitored during the course of the shock load experiment and found to decrease from 46 lm to 30 lm over 35 days in the control, but from 37 lm to \5 lm in the membrane reactor. This decrease in Ñoc size was postulated to be due to the growth of a relatively pure methanogenic bioÐlm on the membrane.1998 Society of Chemical Industry ( J. Chem. T echnol. Biotechnol. 73, 153È161 (1998)

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Stability enhancement of anaerobic digestion through membrane gas extraction under organic shock loads

Voolapalli

Stuckey

1998

J. Chem. Technol. Biotechnol.

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“…According to the theory of hydrogen regulation in anaerobic digestion, due to the oxidation of propionate and butyrate are thermodynamically unfavorable, it is only possible if the intermediate products (especially for hydrogen) are utilized efficiently by the methanogenes, that is, a relative low hydrogen partial pressure is necessary (the hydrogen partial pressure should be lower than 10 Pa) [4,22]. The results showed that hydrogen partial pressure decreased to 9.34 Â 10 À5 atm on the 25th day with the sludge granulation, which provided a suitable thermodynamic condition for the degradation of the two volatile fatty acids, and the specific methanogenic activities of the bacteria were thereby improved.…”

Section: P H 2 and The Maximum Specific Methanogenic Activitiesmentioning

confidence: 99%

Effects of stirring strategies on the sludge granulation in anaerobic CSTR reactor

Hou

Peng

Wang

et al. 2014

Desalination and Water Treatment

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A B S T R A C TThe anaerobic sludge granulation was studied in two laboratory-scale continuous-flow stirred tank reactors (CSTRs), which treating synthetic glucose wastewaters under a mesophilic constant temperature of 35 ± 1˚C. Different stirring strategies were employed in the two CSTRs. Magnetic stirring at a rotation speed of 140 rpm was used in CSTR1 and axial continuous agitation at a speed of 90 rpm in CSTR2. It was observed that highly activated granular sludge formed in CSTR2, but flocculent sludge still remained in CSTR1 after about 45 days' cultivation. Liquid circulation analysis of the two stirring modes displayed that the overall circulation in CSTR2 was more uniform. Furthermore, calculation results proved that the hydraulic shear force produced in CSTR2 was more suitable for granules formation than it in CSTR1, and granules did form in the CSTR2. Therefore, it could be concluded that in the laboratory-scale CSTR, stirring strategy played a key role in sludge granulation. On the other hand, scanning electron microscope images of granular sludge displayed that filamentous bacterial dominated in the outer layer and bacilli surrounded by lots of extracellular polymeric substances in the inner layer. Both of these are beneficial to promote the granules formation and maintenance.

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“…Fermentative H 2 yields can be improved by lowering dissolved H 2 concentrations to create more feasible thermodynamic conditions for high H 2 yielding pathways to proceed (Fynn and Syafila, ; Zhao et al, ; Zheng et al, ). Various H 2 removal strategies have been used to reduce dissolved H 2 concentrations (Liu et al, ; Mizuno et al, ; Tanisho et al, ).…”

Section: Introductionmentioning

confidence: 99%

Changes in glucose fermentation pathways by an enriched bacterial culture in response to regulated dissolved H₂ concentrations

Zheng

Zeng

Duke

et al. 2015

Biotech & Bioengineering

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It is well established that metabolic pathways in the fermentation of organic waste are primarily controlled by dissolved H2 concentrations, but there is no reported study that compares observed and predicted shifts in fermentation pathways induced by manipulating the dissolved H2 concentration. A perfusion system is presented that was developed to control dissolved H2 concentrations in the continuous fermentation of glucose by a culture highly enriched towards Thermoanaerobacterium thermosaccharolyticum (86 ± 9% relative abundance) from an originally diverse consortia in the leachate of a laboratory digester fed with municipal solid waste. Media from a 2.5 L CSTR was drawn through sintered steel membrane filters to retain biomass, allowing vigorous sparging in a separate chamber without cellular disruption. Through a combination of sparging and variations in glucose feeding rate from 0.8 to 0.2 g/L/d, a range of steady state fermentations were performed with dissolved H2 concentrations as low as an equivalent equilibrated H2 partial pressure of 3 kPa. Trends in product formation rates were simulated using a H2 regulation partitioning model. The model correctly predicted the direction of products redistribution in response to H2 concentration changes and the acetate and butyrate formation rates when H2 concentrations were less than 6 kPa. However, the model over-estimated acetate, ethanol and butanol productions at the expense of butyrate production at higher H2 concentrations. The H2 yield at the lowest dissolved H2 concentration was 2.67 ± 0.08 mol H2 /mol glucose, over 300% higher than the yield achieved in a CSTR operated without sparging.

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Hydrogen regulation of acetogenesis from glucose by freely suspended and immobilised acidogenic cells in continuous culture

Cited by 21 publications

References 3 publications

Stability enhancement of anaerobic digestion through membrane gas extraction under organic shock loads

Stability enhancement of anaerobic digestion through membrane gas extraction under organic shock loads

Effects of stirring strategies on the sludge granulation in anaerobic CSTR reactor

Changes in glucose fermentation pathways by an enriched bacterial culture in response to regulated dissolved H₂ concentrations

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Hydrogen regulation of acetogenesis from glucose by freely suspended and immobilised acidogenic cells in continuous culture

Cited by 21 publications

References 3 publications

Stability enhancement of anaerobic digestion through membrane gas extraction under organic shock loads

Stability enhancement of anaerobic digestion through membrane gas extraction under organic shock loads

Effects of stirring strategies on the sludge granulation in anaerobic CSTR reactor

Changes in glucose fermentation pathways by an enriched bacterial culture in response to regulated dissolved H2 concentrations

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Changes in glucose fermentation pathways by an enriched bacterial culture in response to regulated dissolved H₂ concentrations