Biological hydrogen production is a renewable, carbon-neutral and clean route for hydrogen production. Purple non-sulfur (PNS) bacteria have the ability to produce biohydrogen via photofermentation process. The type of the bacterial strain used in photofermentation is known to have an important effect on hydrogen yield. In this study, the effect of different co-cultures of PNS bacteria on photofermentation process was investigated in search of improving the hydrogen yield. For this purpose, growth, hydrogen production and substrate utilization of single and co-cultures of different PNS bacteria (R. capsulatus (DSM 1710), R. capsulatus hup- v (YO3), R. palustris (DSM 127) and R. sphaeroides O.U.001 (DSM 5864)) were compared on artificial H2 production medium in 150 mL photobioreactors under continuous illumination and anaerobic conditions. In general, higher hydrogen yields were obtained via co-cultivation of two different PNS bacteria when compared with single cultures. Further increase in hydrogen yield was observed with co-cultivation of three different PNS bacteria. Co-cultures of two different PNS bacteria have resulted in up to 1.4 and 2.1 fold increase in hydrogen yield and hydrogen productivity. Whereas co-cultures of three different PNS bacteria have resulted in up to 1.6 and 2.0 fold increase in hydrogen yield and hydrogen productivity compared to single cultures. These results indicate that, defined co-cultures of PNS bacteria produce hydrogen at a higher yield and productivity, due most probably to some synergistic relationship. Further studies regarding the physiological and molecular changes need to be carried out for deeper understanding of the mechanism of hydrogen production in co-cultures.

The main objective of this study is exploring the parameters affecting photobiological hydrogen production and developing anaerobic photobioreactor for efficient photofermentative hydrogen production from organic acids in outdoor conditions. Rhodobacter capsulatus and Rhodobacter sphaeroides strains were used as microorganisms. EU project &ldquo / Hyvolution&rdquo / targets to combine thermophilic fermentation with photofermentation for the conversion of biomass to hydrogen. In this study, the effluent obtained by dark fermentation of Miscanthus hydrolysate by T. neapolitana was fed to photobioreactor for photofermentation by R. capsulatus. Hydrogen yield was 1.4 L/Lculture showing that the integration of dark and photofermentation is possible. Innovative elements were introduced to the photobioreactor design such as removal of argon flushing. An online gas monitoring system was developed which became a commercial product. It was found that the light intensity should be at least 270 W/m2 on the bioreactor surface for the highest hydrogen productivity and the hydrogen production decreased by 43 % if infrared light was not provided to the bioreactor. Scale-up of photofermentation process to 25L was achieved yielding 27L hydrogen in 11 days by R. capsulatus on acetate/lactate/glutamate (40/7.5/2 mM) medium. The outdoor application of the system was made. Shading and water spraying were adapted as cooling methods for controlling the temperature of the outdoor bioreactor. It was found that uptake hydrogenase deleted mutant of R. capsulatus show better hydrogen productivity (0.52 mg/L.h) compared to the wild type parent (0.27 mg/L.h) in outdoor conditions. It was also shown that the hydrogen production depended on the sunlight intensity received.

The main aim of this study was to investigate biological hydrogen production from sucrose and molasses by purple non-sulphur bacteria (PNS). The hydrogen production capacities of four different PNS bacteria (Rhodobacter capsulatus (DSM 1710), Rhodobacter capsulatus YO3 (Hup-), Rhodopseudomonas palustris (DSM 127) and Rhodobacter sphaeroides O.U.001 (DSM 5864)) were tested on sucrose and molasses. The photobiological hydrogen production were performed in 50 ml and 150 ml small scale photobioreactors, in batch mode. The produced hydrogen quantities, bacterial growth profiles and pH of the media were recorded through the photobiological hydrogen production processes. Organic acids and sucrose consumption rates were determined by HPLC during the experiments. The maximum hydrogen productivitiy of 0.78 (mmol/lc.h) and 0.55 (mmol/lc.h) was obtained by R. palustris (DSM 127) on sucrose and molasses, respectively. Secondly, co-cultivation of these bacterial strains was studied. The maximum hydrogen productivity by co-cultivation of R. sphaeroides O.U.001 (DSM 5864) and R. palustris (DSM 127) was found as 1.0 (mmol/lc.h).

Effects of temperature and light intensity on photofermentative hydrogen production by Rhodobacter capsulatus DSM1710 by use of acetic and lactic acids as substrates were studied. Experiments were conducted at 20, 30 and 38oC incubator temperatures under light intensities in the 1500 &ndash / 7000 lux range. pH of the medium and quantity of hydrogen forming together with quantity of biomass, and concentrations of acetic, lactic, formic, butyric and propionic acids in the medium were determined periodically. Growth took place and hydrogen was produced under all experimental conditions. Growth was found to increase with increase in temperature but to decrease with increase in light intensity. Total hydrogen produced increased with light intensity up to 6000 lux at 20oC, 5000 lux at 30oC and 3000 lux at 38oC and decreased beyond these values. Medium temperature of about 30oC was found to be optimum for cumulative hydrogen. pH was found to increase slightly and almost all of lactic acid and most of acetic acid was consumed while formic, butyric and propionic acids were first formed and then consumed in the experiments. Growth data fitted well to the logistic model and hydrogen production data fitted well to the Modified Gompertz Model. Lactic acid was found to be almost completely consumed by first order kinetics in early times. Consumption of acetic acid was found to follow zero order kinetics in the early times when lactic acid existed in the system but the order shifted to one later when most of lactic acid was consumed.

Made available in DSpace on 2016-06-02T19:56:35Z (GMT). No. of bitstreams: 1 2404.pdf: 4034212 bytes, checksum: 2913adf06c11c92402ccb17ed7a97fa8 (MD5) Previous issue date: 2009-02-27 / Universidade Federal de Sao Carlos / Hydrogen is a clean and renewable source of energy and it is considered the "fuel of the future", because it produces only water during combustion and when it is used as fuel and hydrogen has a high energy yield of 122 kJ/g, which is 2.75 times greater than hydrocarbon fuels. The hydrogen production using microorganisms is a promising area of technological development from a wide variety of renewable and a alternative for this production is to use the anaerobic fluidized bed reactor (AFBR), a promising reactor for hydrogen production. One of the factors that most influence the performance of AFBR is the support material, which should provide resistance to abrasion, porous surface conducive to colonization by microorganisms, easy fluidization to reach and ability to facilitate the transfer of mass between the middle and biofilm. Thus, the objective of this study was to evaluate the influence of different support materials (polystyrene - R1, ground tire - R2 and PET - R3) for the hydrogen production, using three AFBR. Each reactor had a total volume of 4192 cm3, which was used as carbon source 4000 mg.L-1 of glucose, with pH influent around 7.0 and pH effluent of around 5.5, with hydraulic retention time (HRT) between 8 and 0.5 h, with temperature of 30 o C } 1, with heat treatment of the inoculum. The best performance was R2, giving better hydrogen yield production (HY) (2.15 mol-H2.mol-1-glucose), best H2 content in the biogas (52.97%) and showed a higher glucose conversion (90%). However, the R3 was better in the hydrogen production rate (HPR), 1.07 lh-1.L-1, a secondary parameter in the analysis of performance of the reactors. In all reactors, the production volume of hydrogen and H2 content in biogas increased with the reduction of the TDH, 8 pm to 1 HEO yield of hydrogen production increased with the reduction of the TDH, 8 h for 2 h. The major soluble metabolites during H2 fermentation were acetic acid (HAc), butyric acid (HBu), lactic acid (HLa) and ethanol (EtOH), and a small production of propionic acid and R2 was the reactor that more produced HAc and HBu (42.0% e 36.5%, respectively) . The better performance of R2 can be explained by the roughness of ground tire is larger than the other materials used, accumulating a large quantity of attached biomass, and a greater quantity of bacteria hydrogen producing. There was a predominance of bacilli like Clostridium sp. in the biofilm of all support materials. / O hidrogenio e uma fonte de energia limpa e renovavel e e considerado o combustivel do futuro , pois gera somente agua durante sua combustao e apresenta calor de combustao de 122 kJ.g-1, o que representa 2,75 vezes mais conteudo de energia do que qualquer hidrocarboneto. A producao de hidrogenio usando microrganismos e uma promissora area de desenvolvimento tecnologico a partir de uma ampla variedade de fontes renovaveis e uma das alternativas para esta producao e a utilizacao do reator anaerobio de leito fluidizado (RALF). Um dos fatores que mais influenciam o desempenho do RALF e o material suporte, que deve apresentar resistencia a abrasao, superficie porosa favoravel a colonizacao de microrganismos, facilidade para alcancar a fluidizacao e capacidade de favorecer a transferencia de massa entre o meio e o biofilme. Desta maneira, o objetivo deste trabalho foi avaliar a influencia de diferentes materiais suporte (poliestireno - R1, pneu inservivel triturado - R2 e PET - R3) na producao de hidrogenio utilizando tres reatores anaerobios de leito fluidizado. Cada reator possuia um volume total de 4192 cm3, alimentado com meio contendo glicose como fonte de carbono (4000 mg.L-1), com pH afluente em torno de 7,0 e efluente em torno de 5,5, com tempo de detencao hidraulica (TDH) entre 8 e 0,5 h a uma temperatura de 30oC } 1oC, com tratamento termico do inoculo. O melhor desempenho foi do R2, apresentando melhor rendimento de H2 (2,15 mol-H2.mol-1-glicose), melhor conteudo de H2 no biogas (52,97%) e maior conversao de glicose (90%). Entretanto, o R3 foi melhor na producao volumetrica de H2, 1,07 L.h-1.L-1, um parametro secundario na analise de desempenho dos reatores. Em todos os reatores, a producao volumetrica de hidrogenio e o conteudo de H2 no biogas aumentaram com a reducao do TDH de 8 h para 1 h e o rendimento de producao de hidrogenio aumentou com a reducao do TDH de 8 h para 2 h. Os metabolitos soluveis predominantes em todos os reatores foram acidos acetico, butirico, latico e etanol, havendo uma pequena producao de acido propionico, sendo o R2 o que mais produziu acidos acetico e butirico (42,0% e 36,5%, respectivamente). O melhor desempenho do R2 pode ser explicado pela rugosidade do pneu triturado ser maior do que a dos demais materiais empregados, acumulando uma maior quantidade de biomassa aderida e uma maior quantidade de bacterias acidogenicas produtoras de hidrogenio. Houve predominancia de bacilos semelhantes a Clostridium sp. no biofilme de todos os materiais suporte.