Biohydrogen Production Process Research Articles

Effects of cellulose concentrations on the syntrophic interactions between Clostridium cellulovorans 743B and Rhodopseudomonas palustris CGA009 in coculture fermentation for biohydrogen production

The integration of dark and photo fermentation is a promising strategy to enhance biohydrogen productivity and substrate utilization, and therefore can be adopted to advance the development of industrial biohydrogen production. However, the mutualistic interactions between dark fermentative and purple non-sulfur photosynthetic microorganisms remain poorly understood due to the challenges of incorporating two physiologically different bacteria in one integrated fermentation system. In this work, an experimentally and genetically tractable model combining the cellulose-degrading bacterium Clostridium cellulovorans 743B and photosynthetic bacterium Rhodopseudomonas palustris CGA009 was successfully established. The responses of this coculture system to different cellulose concentrations were characterized. At all four levels of initial cellulose concentrations (2, 3, 4 or 5 g/L), the hydrogen productivity and cellulose degradation of cocultures were all significantly enhanced to varying extents in comparison to monocultures. The mechanism of the beneficial interaction was due to consumption of volatile fatty acids by R. palustris, which in turn balanced the pH to increase cellulose consumption by C. cellulovorans. Overall, the results demonstrated that the mutualism between C. cellulovorans and R. palustris could lead to a more efficient biohydrogen production process, thus making the pairing of these two strains a suitable model for further study on syntrophic interactions.

Bioaugmentation with an anaerobic fungus in a two-stage process for biohydrogen and biogas production using corn silage and cattail

Bioaugmentation with an anaerobic fungus, Piromyces rhizinflata YM600, was evaluated in an anaerobic two-stage system digesting corn silage and cattail. Comparable methane yields of 328.8±16.8mLg−1VS and 295.4±14.5mLg−1VS and hydrogen yields of 59.4±4.1mLg−1VS and 55.6±6.7mLg−1VS were obtained for unaugmented and bioaugmented corn silage, respectively. Similar CH4 yields of 101.0±4.8mLg−1VS and 104±19.1mLg−1VS and a low H2 yield (<1mLg−1VS) were obtained for unaugmented and bioaugmented cattail, respectively. However, bioaugmentation resulted in an initial increase in CH4 and H2 production rates and also increased volatile fatty acid degradation rate for both substrates. Our study demonstrates the potential of bioaugmentation with anaerobic fungus for improving the digestibility of lignocellulose substrates for biogas and biohydrogen production.

Biofilm formation by designed co-cultures of Caldicellulosiruptor species as a means to improve hydrogen productivity.

BackgroundCaldicellulosiruptor species have gained a reputation as being among the best microorganisms to produce hydrogen (H2) due to possession of a combination of appropriate features. However, due to their low volumetric H2 productivities (QH2), Caldicellulosiruptor species cannot be considered for any viable biohydrogen production process yet. In this study, we evaluate biofilm forming potential of pure and co-cultures of Caldicellulosiruptor saccharolyticus and Caldicellulosiruptor owensensis in continuously stirred tank reactors (CSTR) and up-flow anaerobic (UA) reactors. We also evaluate biofilms as a means to retain biomass in the reactor and its influence on QH2. Moreover, we explore the factors influencing the formation of biofilm.ResultsCo-cultures of C. saccharolyticus and C. owensensis form substantially more biofilm than formed by C. owensensis alone. Biofilms improved substrate conversion in both of the reactor systems, but improved the QH2 only in the UA reactor. When grown in the presence of each other’s culture supernatant, both C. saccharolyticus and C. owensensis were positively influenced on their individual growth and H2 production. Unlike the CSTR, UA reactors allowed retention of C. saccharolyticus and C. owensensis when subjected to very high substrate loading rates. In the UA reactor, maximum QH2 (approximately 20 mmol · L−1 · h−1) was obtained only with granular sludge as the carrier material. In the CSTR, stirring negatively affected biofilm formation. Whereas, a clear correlation was observed between elevated (>40 μM) intracellular levels of the secondary messenger bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) and biofilm formation.ConclusionsIn co-cultures C. saccharolyticus fortified the trade of biofilm formation by C. owensensis, which was mediated by elevated levels of c-di-GMP in C. owensensis. These biofilms were effective in retaining biomass of both species in the reactor and improving QH2 in a UA reactor using granular sludge as the carrier material. This concept forms a basis for further optimizing the QH2 at laboratory scale and beyond.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0201-7) contains supplementary material, which is available to authorized users.

Biohydrogen production using psychrophilic bacteria isolated from Antarctica

The growing interest in hydrogen as a fuel has intensified the search of novel approaches for new production processes, among which biohydrogen stands out. Currently mesophilic and thermophilic microorganisms have been used as inocula, and practically no information on the use of psychrophilic microorganisms is available. In this study, the capability of producing biohydrogen by 14 cultivable psychrophilic bacteria, which were isolated from samples of Antarctica, was evaluated. Microorganisms were typified using molecular techniques, and biohydrogen production screening was performed in 120 ml serological bottles with a production medium containing 2.75 g/l tryptone, 0.25 g/l yeast extract, and 20 g/l glucose as carbon source. Results showed that all psychrophilic strains produced biohydrogen from 34.8 to 253.3 ml. Maximum production and production rate of 253.3 ml and 16.64 ml/l/h, respectively were attained by GA051, which is closely related to Janthinobacterium agaricidamnosum (Y08845) with an identity of 98%, whereas the maximum biohydrogen yield of 1.57 mol H2/mol glucose was for the GA024 strain, closely related to Polaromonas jejuensis strain JS12-13 (NR044379) with an identity of 99%. Metabolites were also tested and the main byproducts were organic acids and ethanol. Our results demonstrate that psychrophilic bacteria isolated from Antarctica have a high potential to be used for developing new biotechnological processes for biohydrogen production.

Biohydrogen production from a novel alkalophilic isolate Clostridium sp. IODB-O3

Hydrogen producing bacteria IODB-O3 was isolated from sludge and identified as Clostridium sp. by 16S rDNA gene analysis. In this study, biohydrogen production process was developed using low-cost agro-waste. Maximum H2 was produced at 37°C and pH 8.5. Maximum H2 yield was obtained 2.54±0.2mol-H2/mol-reducing sugar from wheat straw pre-hydrolysate (WSPH) and 2.61±0.1mol-H2/mol-reducing sugar from pre-treated wheat straw enzymatic-hydrolysate (WSEH). The cumulative H2 production (ml/L), 3680±105 and 3270±100, H2 production rate (ml/L/h), 153±5 and 136±5, and specific H2 production (ml/g/h), 511±5 and 681±10 with WSPH and WSEH were obtained, respectively. Biomass pre-treatment via steam-explosion generates ample amount of WSPH which remains unutilized for bioethanol production due to non-availability of efficient C5-fermenting microorganisms. This study shows that Clostridium sp. IODB-O3 is capable of utilizing WSPH efficiently for biohydrogen production. This would lead to reduced economic constrain on the overall cellulosic ethanol process and also establish a sustainable biohydrogen production process.

Revealing the factors influencing a fermentative biohydrogen production process using industrial wastewater as fermentation substrate.

BackgroundBiohydrogen production through dark fermentation using organic waste as a substrate has gained increasing attention in recent years, mostly because of the economic advantages of coupling renewable, clean energy production with biological waste treatment. An ideal approach is the use of selected microbial inocula that are able to degrade complex organic substrates with simultaneous biohydrogen generation. Unfortunately, even with a specifically designed starting inoculum, there is still a number of parameters, mostly with regard to the fermentation conditions, that need to be improved in order to achieve a viable, large-scale, and technologically feasible solution. In this study, statistics-based factorial experimental design methods were applied to investigate the impact of various biological, physical, and chemical parameters, as well as the interactions between them on the biohydrogen production rates.ResultsBy developing and applying a central composite experimental design strategy, the effects of the independent variables on biohydrogen production were determined. The initial pH value was shown to have the largest effect on the biohydrogen production process. High-throughput sequencing-based metagenomic assessments of microbial communities revealed a clear shift towards a Clostridium sp.-dominated environment, as the responses of the variables investigated were maximized towards the highest H2-producing potential. Mass spectrometry analysis suggested that the microbial consortium largely followed hydrogen-generating metabolic pathways, with the simultaneous degradation of complex organic compounds, and thus also performed a biological treatment of the beer brewing industry wastewater used as a fermentation substrate.ConclusionsTherefore, we have developed a complex optimization strategy for batch-mode biohydrogen production using a defined microbial consortium as the starting inoculum and beer brewery wastewater as the fermentation substrate. These results have the potential to bring us closer to an optimized, industrial-scale system which will serve the dual purpose of wastewater pre-treatment and concomitant biohydrogen production.

Upscaling of biohydrogen production process in semi-pilot scale biofilm reactor: Evaluation with food waste at variable organic loads

The present account focuses on upscaling of biohydrogen (H2) production at semi-pilot scale bioreactor using composite food waste. Experiments were conducted at different organic load (6, 12, 18, 30, 40, 50 and 66 g COD/l) conditions. H2 production increased with an increasing organic load up to 50 g COD/l (9.67 l/h) followed by 40 g COD/l (6.48 l/h), 30 g COD/l (1.97 l/h), 18 g COD/l (0.90 l/h), 12 g COD/l (0.78 l/h) and 6 g COD/l (0.32 l/h). H2 production was affected by acidification (pH drop to 3.96) at 66 g COD/l operation due to the excess accumulation of soluble metabolites (5696 mg VFA/l). Variation in organic load of food waste influenced the overall hydrogen production efficiency.

Operation of a bioelectrochemical system as a polishing stage for the effluent from a two-stage biohydrogen and biomethane production process

Anaerobic bioenergy production processes including fermentative biohydrogen (BioH2), anaerobic digestion (AD) and bioelectrochemical system have been investigated for converting municipal waste or various biomass feedstock to useful energy carriers. However, the performance of a microbial fuel cell (MFC) fed on the effluent from a two-stage biogas production process has not yet been investigated extensively in continuous reactor operation on complex substrates. In this study we have investigated the extent to which a microbial fuel cell (MFC) can reduce COD and recover further energy from the effluent of a two-stage biohydrogen and biomethane system. The performance of a four-module tubular MFC was determined at six different organic loadings (0.036–6.149gsCODL−1d−1) in terms of power generation, COD removal efficiency, coulombic efficiency (CE) and energy conversion efficiency (ECE). A power density of 3.1Wm−3 was observed at the OLR=0.572gsCODL−1d−1, which resulted in the highest CE (60%) and ECE (0.8%), but the COD removal efficiency decreased at higher organic loading rates (35.1–4.4%). The energy recovery was 92.95JL−1 and the energy conversion efficiency, based on total influent COD was found to be 0.48–0.81% at 0.572gsCODL−1d−1. However, the energy recovery by the MFC is only reported for a four-module reactor and improved performance can be expected with an extended module count, as chemical energy remained available for further electrogenesis.

Continuous biohydrogen and biomethane production from whey permeate in a two‐stage fermentation process

This study focuses on the exploitation of the two‐stage continuous fermentation process for biohydrogen and biomethane production from whey permeate. Mesophilic fermentative biohydrogen production was investigated at a constant hydraulic retention time (HRT) of 24 h and organic loading rates (OLRs) of 20, 25, 30, and 35 kg COD/m3·d. The hydrogenogenic reactor was successfully operated at OLR of 30 kg COD/m3·d when the proportion of hydrogen in biogas, volumetric productionrsquo rate of hydrogen, and hydrogen yield reached the maximum values of 44.6 ± 0.8%, 5.26 ± 0.15 L H2/d, and 4.19 mol H2/kg CODremoved, respectively. The effluent from hydrogenogenic reactor was further digested to biogas in the second reactor operated at a HRT of 3 d and variable OLR in the range of 0.9–1.9 kg COD/m3·d. Maximum biogas production rate, volumetric production rate of methane and methane yield were 16.90 ± 0.6 L/d, 11.95 ± 0.6 L CH4/d, and 0.12 m3 CH4/kg CODadded. The total chemical oxygen demand elimination from whey permeate reached 98% in a two‐stage process. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1411–1418, 2014

Effect of the culture media optimization, pH and temperature on the biohydrogen production and the hydrogenase activities by Klebsiella pneumoniae ECU-15

The low yield of the biohydrogen production is the main constraint for its industrialization process. In order to improve its production, medium compositions of the hydrogen fermentation by Klebsiella pneumoniae ECU-15 were optimized through the response surface methodology (RSM). Experimental results showed that the optimum hydrogen production of 5363.8 ml/L was obtained when the concentration of glucose, the ammonium sulfate and the trace elements were 35.62 g/L, 2.78 g/L and 23.15 ml/L at temperature 37.0°C, pH 6.0. H2 evolving hydrogenase was greatly enhanced by the optimization of the medium compositions. The activity of H2 evolving hydrogenase increased with the temperature, and decreased with the pH, while the activity of the uptake hydrogenase increased with the temperature and the pH. So the biohydrogen production process of the K. pneumoniae ECU-15 was the comprehensive results of the evolution hydrogen process and the uptake hydrogen process.

Ecologically engineered submerged and emergent macrophyte based system: An integrated eco-electrogenic design for harnessing power with simultaneous wastewater treatment

Miniatured ecologically engineered submerged and emergent macrophyte based integrated system (SEMS) was designed by embedding with sediment type fuel cells to harness bioelectricity with simultaneous wastewater treatment. The designed eco-electrogenic system was operated in a continuous mode for 210 days using treated sewage and fermented distillery wastewater (acidogenic effulents from biohydrogen production process). Four fuel cell setups showed feasibility of power production with domestic wastewater (A1C1: 97.99mW/m2; A2C2: 92.56mW/m2; A3C3: 128.09mW/m2and A4C4: 84.76mW/m2) which comparatively improved with fermented distillery wastewater (A1C1: 179.78mW/m2; A2C2: 175.56mW/m2; A3C3: 160.70mW/m2; A4C4: 140.99mW/m2) but decreased with further increase in the load. Electrode assemblies connected in series showed stabilized power production (780±22mV; 4.14±0.19mA) for longer period. Polarization behavior of combined fuel cells also depicted a decrement in the ohmic and activation losses. The ecologically engineered electrogenic system documented good COD, VFA, color, nitrates and turbidity removal during operation.

Effects of biomass, COD and bicarbonate concentrations on fermentative hydrogen production from POME by granulated sludge in a batch culture

Effects of three selected variables viz. biomass concentration, initial chemical oxygen demand (COD) concentration and initial bicarbonate alkalinity (BA) on biological hydrogen production from palm oil mill effluent (POME) using the granulated sludge in batch culture were investigated. The experimental results were analyzed and modeled using a central composite design (CCD) of response surface methodology (RSM). In order to carry out a comprehensive analysis of the biohydrogen production process, indicative parameters namely hydrogen yield (YH), specific hydrogen production rate (SHPR), and COD removal efficiency were studied as the process responses. Maximum hydrogen yield (124.5 mmol H2/g CODremoved) and specific hydrogen production rate (55.42 mmol H2/g VSS.d) were achieved at CODin 3000 and 6500 mg/l, MLVSS 4000 and 2000 mg/l, and initial BA 1100 mg CaCO3/l, respectively.

Improvement of hydrogen production with thermophilic mixed culture from rice spent wash of distillery industry

Abstract Biohydrogen production processes were investigated using thermophilic bacterial consortia enriched from sludge of the anaerobic digester. A multiple parameter optimization viz. temperature, pH and substrate concentration was performed for maximization of hydrogen production. Heat shock pre-treatment followed by BES (2-bromo ethane sulfonate) treatment was done for the enrichment of hydrogen producing bacteria. Box–Behnken design and response surface methodology were adopted to investigate the mutual interaction among the process parameters. Experimental optimization of process parameters (60 °C, pH 6.5 and 10 g/L) gave the maximum hydrogen production and yield of 3985 mL/L and 2.7 mol/mol glucose respectively in the batch system which is higher than the reported value on UASB. These experimental parameters found concurrent with the values obtained from the theoretical model i.e. 58.4 °C, pH 6.6, 10.8 g/L and yield of 2.71 mol/mol glucose. At optimized conditions, maximum hydrogen production rate ( R m ) of 850 mL/h, gas production potential ( P ) of 4551 mL/L and lag time ( λ ) of 1.98 h were determined using modified Gompertz equation. Using the optimum conditions, hydrogen production from rice spent wash was conducted in which hydrogen yield of 464 mL/g carbohydrate and hydrogen production rate of 168 mL/L h were obtained. PCR-DGGE profile showed that the thermophilic mixed culture was predominated with species closely affiliated to Thermoanaerobacterium sp.

Influences of Environmental and Operational Factors on Dark Fermentative Hydrogen Production: A Review

AbstractHydrogen (H2) is one of renewable energy sources known for its non‐polluting and environmentally friendly nature, as its end combustion product is water (H2O). The biological production of H2 is a less energy intensive alternative where processes can be operated at ambient temperature and pressure. Dark fermentation by bacterial biomass is one of multitude of approaches to produce hydrogen which is known as the cleanest renewable energy and is thus receiving increasing attention worldwide. The present study briefly reviews the biohydrogen production process with special attention on the effects of several environmental and operational factors towards the process. Factors such as organic loading rate, hydraulic retention time, temperature, and pH studied in published reports were compared and their influences are discussed in this work. This review highlights the variations in examined operating ranges for the factors as well as their reported optimum values. Divergent values observed for the environmental/operational factors merit further exploration in this field.

Fatty acid rich effluent from acidogenic biohydrogen reactor as substrate for lipid accumulation in heterotrophic microalgae with simultaneous treatment

Acid-rich effluent generated from acidogenic biohydrogen production process was evaluated as substrate for lipid synthesis by integrating with heterotrophic cultivation of mixed microalgae. Experiments were performed both with synthetic volatile fatty acids (SVFA) and fermented fatty acids (FFA) from biohydrogen producing reactor. Fatty acid based platform evidenced significant influence on algal growth as well as lipid accumulation by the formation of triglycerides through fatty acid synthesis. Comparatively FFA documented higher biomass and lipid productivity (1.42mg/ml (wet weight); 26.4%) than SVFAs ((HAc+HBu+HPr), 0.60mg/ml; 23.1%). Lipid profiles varied with substrates and depicted 18 types of saturated and unsaturated fatty acids with wide fuel and food characteristics. The observed higher concentrations of Chl b over Chl a supports the biosynthesis of triacylglycerides. Microalgae diversity visualized the presence of lipid accumulating species viz., Scenedesmus sp. and Chlorella sp. Integration of microalgae cultivation with biohydrogen production showed lipid productivity for biodiesel production along with additional treatment.

Enzymatic dynamics of microbial acid tolerance response (ATR) during the enhanced biohydrogen production process via anaerobic digestion

Organic acid especially butyric acid accumulation can inhibit fermentative hydrogen production. However acid tolerance could be increased when mixed cultures adapted to butyric acid stress in an intentional and continuous operation. As compared to the original cultures, the yield and productivity of hydrogen were enhanced by 56.5% with more acid production and a higher HAc/HBu (acetic acid/butyric acid) of 1.33 by the evolved cultures. The enhancement was due to the increase of acid tolerance with more acid tolerance response (ATR) induction. Later the representative enzymatic ATR systems were investigated in this study. It was found that two ATR systems including H+-ATPase and hydrogenase played important roles in hydrogen evolution and the evolved cultures had a higher overall induction. Furthermore, the dynamics of the ATR systems indicated that hydrogen-producing microorganisms with acid tolerance could prepare themselves better against self-produced acid stress and the evolved cultures had a better stress anticipation possibly due to the bacterial communities change via adaptive evolution.

Comparative assessment of single-stage and two-stage anaerobic digestion for the treatment of thin stillage

A comparative evaluation of single-stage and two-stage anaerobic digestion processes for biomethane and biohydrogen production using thin stillage was performed to assess the impact of separating the acidogenic and methanogenic stages on anaerobic digestion. Thin stillage, the main by-product from ethanol production, was characterized by high total chemical oxygen demand (TCOD) of 122g/L and total volatile fatty acids (TVFAs) of 12g/L. A maximum methane yield of 0.33L CH4/gCODadded (STP) was achieved in the two-stage process while a single-stage process achieved a maximum yield of only 0.26L CH4/gCODadded (STP). The separation of acidification stage increased the TVFAs to TCOD ratio from 10% in the raw thin stillage to 54% due to the conversion of carbohydrates into hydrogen and VFAs. Comparison of the two processes based on energy outcome revealed that an increase of 18.5% in the total energy yield was achieved using two-stage anaerobic digestion.

Sliding mode observer for biomass estimation in a biohydrogen production process

This work deals with the problem of estimation of biomass concentration and specific growth rate in a biohydrogen production process. A photo-fermentation process with the photosynthetic bacteria Rhodobacter capsulatus is considered. The reaction dynamics is represented with a Monod law while the hydrogen production rate is modeled with a Luedeking-Piret expression. A sliding mode observer is proposed and designed, which gives an estimate of both biomass concentration and specific growth rate from measurements of the produced hydrogen volume. The proposed observer is completely robust against the growth kinetic model, and it presents a first-order reduced dynamics. Numerical simulation results are presented for a batch biohydrogen production process.

A Computational Fluid Dynamics (CFD) Study into a Hydrodynamic Factor that Affects a Bio-Hydrogen Production Process in a Stirred Tank Reactor

A Computational Fluid Dynamics (CFD) Study into a Hydrodynamic Factor that Affects a Bio-Hydrogen Production Process in a Stirred Tank Reactor

Regulatory function of divalent cations in controlling the acidogenic biohydrogen production process

The functional role of divalent cations viz., iron (Fe2+), magnesium (Mg2+), nickel (Ni2+), zinc (Zn2+) and manganese (Mn2+) in regulating the biohydrogen (H2) production potential of a biocatalyst was evaluated under varying concentrations. The optimum conditions were evaluated in detail and compared with the principle conditions for enhanced conversion efficiency. Higher concentration of Fe2+ showed an enhanced H2 production efficiency of the biocatalyst (61.94 mmol) due to its role as a component of hydrogenase and ferredoxin. On the contrary, a higher concentration of Mg+2 showed a higher substrate utilization capability (76.46%) of the biocatalyst. The optimum metal concentration showed a higher H2 yield (18.23 mol kg−1 CODR; 3.5 mol mol−1 glucose) over principle operation conditions (14.76 mol kg−1 CODR; 2.84 mol mol−1 glucose). Higher concentrations of acetate (78 ± 6%) as the metabolic intermediate over butyrate (12 ± 2%) supported the observed higher H2 yields. Higher reductive catalytic current over oxidative current along with the enhanced dehydrogenase activity supported the higher H2 production efficiency. Shift in the redox Tafel slope was witnessed near zero in the case of Fe2+ and optimum conditions indicating the simultaneous oxidation and reduction reactions facilitating the availability of higher number of protons through metabolite inter-conversions that can make H2. The presence of divalent cations at an optimum concentration will enhance the H2 production capability of the biocatalyst. However, elevated levels of metal concentration showed a negative influence on the biocatalyst efficiency.