Bio-hydrogen production by mixed culture of photo-and dark-fermentation bacteria (original) (raw)
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Enhanced bio-hydrogen production by the combination of dark-and photo-fermentation in batch culture
Bioresource technology, 2010
In this study, some key factors, for example, diluted ratio of effluents, the ratio of dark-photo bacteria, light intensity and light/dark cycle influencing hydrogen production by combining Clostridium butyricum and immobilized Rhodopseudomonas faecalis RLD-53 in batch culture, were investigated. Experimental results showed the photo-hydrogen yield decreased when increasing diluted ratio from 1:0.5 to 1:3, and it reached the maximum value of 4368 ml-H 2 /l-effluents at the ratio of 1:0.5. When the ratio of dark-photo bacteria was at 1:2, the hydrogen yield reached highest value of 4.946 mol-H 2 /mol-glucose and cumulative hydrogen volume was 5357 ml-H 2 /l-culture during the combination process. When the light intensity was at 10.25 W/m 2 , the hydrogen volume of photo-fermentation and the combination process reached maximum value of 4260 ml-H 2 /l-effluents and 5892 ml-H 2 /l-culture, respectively. During the combination process, maximum total hydrogen yield was 5.374 mol-H 2 /mol-glucose. Meanwhile, hydrogen production under light/dark cycle was evaluated.
Use of mixed culture bacteria for photofermentive hydrogen of dark fermentation effluent
Bioresource Technology, 2014
Mixed culture bacteria is a good candidate for photofermentive hydrogen process. Photofermentive hydrogen process is HRT and OLR dependant. R. palustris species is dominat bacteria in the photobioreactor. H 2 yield was mainly due to the conversion of COD in the soluble form. CODt/NH 4 -N ratio (8.8-12.8) does not influence the amount of hydrogen yield.
Applied Microbiology and Biotechnology, 2005
Combined dark and photo-fermentation was carried out to study the feasibility of biological hydrogen production. In dark fermentation, hydrogen was produced by Enterobacter cloacae strain DM11 using glucose as substrate. This was followed by a photo-fermentation process. Here, the spent medium from the dark process (containing unconverted metabolites, mainly acetic acid etc.) underwent photo-fermentation by Rhodobacter sphaeroides strain O.U.001 in a column photo-bioreactor. This combination could achieve higher yields of hydrogen by complete utilization of the chemical energy stored in the substrate. Dark fermentation was studied in terms of several process parameters, such as initial substrate concentration, initial pH of the medium and temperature, to establish favorable conditions for maximum hydrogen production. Also, the effects of the threshold concentration of acetic acid, light intensity and the presence of additional nitrogen sources in the spent effluent on the amount of hydrogen produced during photo-fermentation were investigated. The light conversion efficiency of hydrogen was found to be inversely proportional to the incident light intensity. In a batch system, the yield of hydrogen in the dark fermentation was about 1.86 mol H2 mol−1 glucose; and the yield in the photo-fermentation was about 1.5–1.72 mol H2 mol−1 acetic acid. The overall yield of hydrogen in the combined process, considering glucose as the preliminary substrate, was found to be higher than that in a single process.
International Journal of Hydrogen Energy, 2010
Pure culture of Rhodobacter sphaeroides (NRRL-B1727) was used for continuous photofermentation of volatile fatty acids (VFA) present in the dark fermentation effluent of ground wheat starch. The feed contained 1950 AE 50 mg L À1 total VFA with some nutrient supplementation. Hydraulic residence time (HRT) was varied between 24 and 120 hours. The highest steady-state daily hydrogen production (55 ml d À1) and hydrogen yield (185 ml H 2 g À1 VFA) were obtained at HRT ¼ 72 hours (3 days). Biomass concentration increased with increasing HRT. Volumetric and specific hydrogen formation rates were also maximum at HRT ¼ 72 h. High extent of TVFA fermentation at HRT ¼ 72 h resulted in high hydrogen gas production.
Fermentative hydrogen production by microbial consortium
International Journal of …, 2008
Heat pre-treatment of the inoculum associated to the pH control was applied to select hydrogen-producing bacteria and endospores-forming bacteria. The source of inoculum to the heat pre-treatment was from a UASB reactor used in the slaughterhouse waste treatment. The molecular biology analyses indicated that the microbial consortium presented microorganisms affiliated with Enterobacter cloacae (97% and 98%), Clostridium sp. (98%) and Clostridium acetobutyricum (96%), recognized as H 2 and volatile acids' producers. The following assays were carried out in batch reactors in order to verify the efficiencies of sucrose conversion to H 2 by the microbial consortium: (1) 630.0 mg sucrose/L, (2) 1184.0 mg sucrose/L, (3) 1816.0 mg sucrose/L and (4) 4128.0 mg sucrose/L. The subsequent yields were obtained as follows: 15% (1.2 mol H 2 /mol sucrose), 20% (1.6 mol H 2 /mol sucrose), 15% (1.2 mol H 2 /mol sucrose) and 4% (0.3 mol H 2 /mol sucrose), respectively. The intermediary products were acetic acid, butyric acid, methanol and ethanol in all of the anaerobic reactors.
Journal of Bioscience and Bioengineering, 2014
The effect of individual and combined mixed culture on dark fermentative hydrogen production performance was investigated. Mixed cultures from cow dung (C1), sewage sludge (C2), and pig slurry (C3) were enriched under strict anaerobic conditions at 37 C with glucose as the sole carbon source. Biochemical hydrogen production test in peptoneyeast-glucose (PYG) and basal medium was performed for individual mixed cultures (C1, C2 and C3) and their combinations (C1eC2, C2eC3, C1eC3 and C1eC2eC3) at a glucose concentration of 10 g/L, 37 C and initial pH 7. Maximum hydrogen yields (HY) of 2.0 and 1.86 mol H2 =mol glucose by C2, and 1.98 and 1.95 mol H2 =mol glucose by C2eC3 were obtained in PYG and basal medium, respectively. Butyrate and acetate were the major soluble metabolites produced by all the cultures, and the ratio of butyrate to acetate was w2 fold higher in basal medium than PYG medium, indicating strong influence of media formulation on glucose catabolism. The major hydrogen-producing bacterial strains, observed in all mixed cultures, belonged to Clostridium butyricum, C. saccharobutylicum, C. tertium and C. perfringens. The hydrogen production performance of the combined mixed culture (C2eC3) was further evaluated on beverage wastewater (10 g/L) at pH 7 and 37 C. The results showed an HY of 1.92 mol H2 =mol glucoseÀequivalent. Experimental evidence suggests that hydrogen fermentation by mixed culture combination could be a novel strategy to improve the HY from industrial wastewater.
International Journal of Hydrogen Energy, 2016
In the present study, a new purple non sulfur (PNS) bacterial strain identified as Rhodobacter sphaeroides CNT 2A was investigated for photo fermentative hydrogen production from acetate, butyrate (short chain organic acids), glucose & sucrose (simple and complex sugar) as sole carbon source in presence of sodium glutamate (0.6 g/L) as nitrogen source. Initial medium pH, acetate and butyrate concentration (by using these substrates as sole carbon sources) were optimized. At optimum pH 8, hydrogen yield efficiency obtained from acetate and butyrate were 2.1 ± 0.2 mol H 2 /mole and 2.9 ± 0.2 mol H 2 /mole substrate consumed, respectively. Hydrogen production obtained from glucose and sucrose were; 0.46 ± 0.05 mol H 2 /mole and 2.4 ± 0.2 mol H 2 /mole, respectively. This study imply that CNT 2A encompasses carbohydrate catabolic pathway and thus can utilize carbohydrates (both simple as well as complex sugar) directly.