Photo-fermentation Process Research Articles

Biohydrogen and poly-β-hydroxybutyrate production by winery wastewater photofermentation: Effect of substrate concentration and nitrogen source

The applicability and convenience of biohydrogen and poly-β-hydroxybutyrate production through single-stage photofermentation of winery wastewater is demonstrated in the present study. Experiments are conducted using a purple non-sulfur bacteria mixed consortium, subject to variable nutrient conditions, to analyze the effect of initial chemical oxygen demand and the available nitrogen source on the metabolic response. Results show that winery wastewater is a promising substrate for photofermentation processes, despite the presence of inhibiting compounds such as phenolics. Nonetheless, the initial chemical oxygen demand must be carefully controlled to maximize hydrogen production. Up to 468 mL L−1 of hydrogen and 203 mg L−1 of poly-β-hydroxybutyrate can be produced starting from an initial chemical oxygen demand of 1500 mg L−1. The used nitrogen source may direct substrate transformation through different metabolic pathways. Interestingly, the maximum production of both hydrogen and poly-β-hydroxybutyrate occurred when glutamate was used as the nitrogen source.

Evaluation of biohydrogen yield potential and electron balance in the photo-fermentation process with different initial pH from starch agricultural leftover

Starch agricultural leftover is a potential substrate for photosynthetic bacteria to produce hydrogen. In this work, the effect of initial pH on photo-fermentation biohydrogen production process and electron balance were investigated. The modified Gompertz model was adopted, and hydrogen yield, sugar consumption and metabolite evolution were monitored with initial pH varying from 5 to 9. Results showed that hydrogen was produced mainly through acetic acid and butyric acid metabolism pathways when starch taken as carbon source. It was found that the maximum hydrogen yield (642 ± 22 mL) and highest hydrogen production rate (77.78 mL/(L·h)) were obtained at initial pH of 7. 37.65% substrates electrons diverted towards hydrogen. Lower hydrogen yield, hydrogen production rate and lower electrons diversion were obtained at other initial pH levels. Also, the lag phase time was 0.04 h when pH was 7, which was significantly lower than other levels.

Enhancement of bio-hydrogen yield and pH stability in photo fermentation process using dark fermentation effluent as succedaneum

The photo fermentation hydrogen yield from dark fermentation effluents (DFEs) can be promoted by adding corn straw enzymatic hydrolysate adjusts the nutritional composition of DFEs. As compared with the control group (without enzymatic hydrolysate addition), the effect of adding enzymatic hydrolysate make H2 yield increase from 312.54 to 1287.06 mL H2/g TOC, and maximum hydrogen production rate increase 2.14 to 10.23 mL/h. On the other hand, buffer reagents remained in DFEs make which can replace part sodium citrate buffer to maintain pH stability in synchronized saccharification and photosynthetic fermentation process with corn straw as substrate, the best result was observed at the ration of 1:2 (33 mL DFEs, 67 mL sodium citrate buffer) with the hydrogen yield of 436.30 ± 10 mL, and which can cut down the GHG in the life cycle of hydrogen production.

Paperboard mill wastewater treatment via combined dark and LED-mediated fermentation in the absence of external chemical addition

Paperboard mill wastewater (PMWW) was treated using two subsequent dark and photo up-flow intermitted stirring tank reactors (UISTRs) under different hydraulic retention times (HRTs) without external chemical use. HRT of 12 h revealed the maximum overall H2 productivity of 1394.1(±70.6) mL/L/d with contents of 48.9(±2.5) and 47.4(±1.4)% for dark- and photo-processes, respectively. Overall substrate removal efficiency (SDE) of 58.9(±4.5)% was registered at HRT o 12 h. High H2 productivity was ascribed to fermentation type occurred at dark reactor, since acetate and butyrate accounted for 70.9% of volatile fatty acids. Besides, pH and carbon to nitrogen ratio of dark reactor’s effluent at HRT = 12 h were 5.5(±0.1) and 30.0(±2.5), respectively which are the optimum levels for photo fermentation process. Moreover, energetic and economic analyses emphasized on the superiority of 12 h-HRT, where net gain energy, daily saving and payback period accounted for 1319.5 kWh/d, 148.7 $/d and 9.8 years, respectively.

Enhanced hydrogen production by a sequential dark and photo fermentation process: Effects of initial feedstock composition, dilution and microbial population

Two-stage process of dark fermentation (DF) and photo fermentation (PF), using fruit and vegetable waste (FVW) and cheese whey powder (CWP), was used as an approach to enhance the hydrogen (H2) production. FVW and CWP at C/N ratios of 34, 39, 60, 71 and 82 were tested as substrates for DF. Dilution (1:2, 1:5, 1:10) of the DF effluents was used as a coupling strategy. DF effluents with low-butyrate and high lactate concentrations were obtained as a function of an increased C/N ratio, which results in high H2 production during the PF. Maximum overall H2 yields of 793.7 and 695.4 mLH2/gChemical Oxygen Demand (COD) were obtained using a 1:10 dilution, at a C/N ratio of 60 and 70, respectively. These H2 yields were higher than those obtained with the individual processes. The C/N ratio at the DF stage regulate not only H2 production but also the distribution and concentrations of by-products. These metabolites, in turn, control the H2 production during the PF. Predominant microbial population for both processes (DF: C/N = 34 Acetobacter lovaniensis, Clostridium butyricum; C/N = 39 C. butyricum, Enterobacter sp, Bifidobacterium; C/N = 82 Lactobacillus casei; PF: Rhodopseudomonas palustris) were in accordance with the final metabolic products.

光发酵工艺金华火腿氨基酸含量分析

光发酵工艺金华火腿氨基酸含量分析

Photohydrogen production from dark-fermented palm oil mill effluent (DPOME) and statistical optimization: Renewable substrate for hydrogen

Biological hydrogen production through photo-fermentative process using dark fermented palm oil effluent (DPOME) is a cost effective and environmentally benign process. In this study, effect of various factors like light intensity, agitation rate and dilution of DPOME on the hydrogen productivity of Rhodopseudomanas palustris were investigated using batch system. Investigation methods like response surface methodology (RSM) and Box-Behnken design were employed to investigate the optimum conditions for enhanced photo-fermentative hydrogen production. The regression analysis suggested that hydrogen yield was well fitted by a quadratic polynomial equation (R2 = 0.92). The hydrogen production was investigated by varying the intensity levels of these three independent variables, in which all have significant influences on hydrogen yield. The set of 19 experimental runs were conducted to optimize these variables. The highest hydrogen yield of 3.07 ± 0.66 H2 yield mol-H2/mol-acetate was obtained under the optimum condition of light intensity 250 W/m2, agitation rate 200 rpm, and 30% dilution of DPOME. The experimentally obtained hydrogen yield found out to be in a good agreement with predicted yield which was about 2.80 mol-H2/mol-acetate. In short, results suggest that experimental strategy using RSM approach along with Box-Behnken design can be a promising approach to achieve enhanced biological hydrogen production.

Biohydrogen production from chewing gum manufacturing residue in a two-step process of dark fermentation and photofermentation

Abstract Two-step hybrid system of microbiological hydrogen production with the diluted solid wastes from chewing gum production as a substrate was studied. As the first step, dark fermentation with the digested sludge at different concentrations of waste was performed. The effluent originating from the dark process was subsequently applied in photofermentation with Rhodobacter sphaeroides bacteria. In the first step, the degradation of sweetening substances as well as Talha gum remaining in waste was observed. Hydrogen, carbon dioxide and liquid metabolites (Volatile Fatty Acids - VFAs) were the main products. The maximum hydrogen production in dark fermentation (0.36 L/Lmedium) was observed at concentration of 67 g waste/L. Effluents from the first step, containing mainly xylitol, butyric, acetic, lactic and propionic acids, served as the source of organic carbon for photofermentation. The maximum amount of hydrogen at this step reached 0.80 L H2/L of diluted (1:8) effluent. The presence of significant concentration of ammonium ions (∼480 mg/L) in non-diluted effluent completely ceased the hydrogen formation by nitrogenase, therefore reduction in the amount of NH4+ ions in the medium was necessary. This was realized by the dilution of effluent from dark fermentation. The total amount of hydrogen produced in sequential dark and photo-fermentation process under the optimized reaction conditions reached the volume of ∼6.7 L H2/L of non-diluted waste.

Bio-hydrogen production from waste materials: A review

When hydrogen burns in air, it produces nothing but water vapour. It is therefore the cleanest possible, totally non-polluting fuel. This fact has led some people to propose an energy economy based entirely on hydrogen, in which hydrogen would replace gasoline, oil, natural gas, coal, and nuclear power. Hydrogen is a clean energy source. Therefore, in recent years, demand on hydrogen production has increased considerably. Electrolysis of water, steam reforming of hydrocarbons and auto-thermal processes are well-known methods for hydrogen gas production, but not cost-effective due to high energy requirements. As compare to chemical methods, biological production of hydrogen gas has significant advantages such as bio-photolysis of water by algae, dark and photo-fermentation of organic materials, usually carbohydrates by bacteria. New approach for bio-hydrogen production is dark and photo-fermentation process but with some major problems like dark and photo-fermentative hydrogen production is the raw material cost. By using suitable bio-process technologies hydrogen can be produced through carbohydrate rich, nitrogen deficient solid wastes such as cellulose and starch containing agricultural and food industry wastes and some food industry wastewaters such as cheese whey, olive mill and baker's yeast industry wastewaters. Utilization of aforementioned wastes for hydrogen production provides inexpensive energy generation with simultaneous waste treatment. This review article summarizes bio-hydrogen production from some waste materials with recent developments and relative advantages.

A Road Map on Biohydrogen Production from Organic Wastes

Fossil fuels play important role in the economy of industrialized countries of the world. However, these sources of energy are not renewable and nearing the brink of extinction. Moreover, the reliance on these fuels has led to increased levels of pollution which have caused serious adverse impacts on the environment. Hydrogen has emerged as a promising alternative since it does not produce CO2 and also has the highest calorific value. The biological H2 production has an edge over its chemical counterpart mainly because it is environmentally benign. However, the major challenge limiting the transition from an oil based economy to that of biohydrogen is the low hydrogen production rate, yield and economy of the process. Biohydrogen production by dark fermentation is found most promising as compared to other biohydrogen production processes like photo fermentation process using photofermentative bacteria, microalgae, microbial fuel cell etc. Present research group has been involved in biohydrogen research for last two decades. Suitability of different organic wastes for the hydrogen production has been developed. Both pure microbial cultures and acidogenic cultures obtained from anaerobic digester are found suitable for the hydrogen production. One 10,000 L pilot plant studies are carried out for the commercial exploitation of the process. The spent medium of the dark fermentation process mostly comprises of acetic acid, butyric acid etc., which are the substrates for the biomethanation process for the generation of methane and carbon dioxide. So, maximization of gaseous energy is possible dark fermentation followed by methanation process which is known as biohythane process.

Utilization of distillery wastewater for hydrogen production in one-stage and two-stage processes involving photofermentation.

In this study, distillery wastewater was treated by dark fermentation or photofermentation alone, and by sequential dark and photofermentation processes using anaerobic saccharolytic consortium and purple nonsulfur bacteria. Combination of dark and photofermentation resulted in the maximal H2 yield of 17.6L/L of distillery waste with chemical oxygen demand 40g/L. It is equivalent to 205kJ/L distillery wastewater and corresponds to recovery of approximately 4-8% of energy consumed during ethanol production. Optimal performance of photofermentation was observed at 20% concentration of pre-fermented distillery waste. In photofermentation, the range of the suitable distillery waste concentrations was extended and the H2 yield was improved by choosing the tolerant strain of purple bacteria Rhodobacter sphaeroides B-3059. After two stages, organic acids and sugars were completely consumed that means wastewater treatment concomitant to H2 production.

Single-stage photofermentative biohydrogen production from sugar beet molasses by different purple non-sulfur bacteria.

Biohydrogen production via fermentative routes offers considerable advantages in waste recycling and sustainable energy production. This can be realized by single-stage dark or photofermentative processes, or by a two-stage integrated process; the latter offering the higher production yields due to complete conversion of sugar substrates into H2 and CO2. However, problems arising from the integration of these two processes limit its scale-up and implementation. Hence, high efficiency one-step fermentative biohydrogen production processes from sugar-rich wastes are preferable. In this study, different strains of purple non-sulfur bacteria were investigated for their biohydrogen production capacity on pure sucrose and sugar beet molasses, and the feasibility of single-stage photofermentative biohydrogen production was evaluated. A single-stage photofermentation process was carried out using four different strains of purple non-sulfur bacteria (Rhodobacter capsulatus DSM 1710, R. capsulatus YO3, Rhodobacter sphaeroides O.U.001, and Rhodopseudomonas palustris DSM 127) on different initial sucrose concentrations. The highest hydrogen yield obtained was 10.5mol H2/mol of sucrose and the maximum hydrogen productivity was 0.78mmol/Lh by Rp. palustris on 5mM sucrose. A hydrogen yield of 19mol H2/mol sucrose, which represents 79% of theoretical yield, and a maximum hydrogen productivity of 0.55mmol/L h were obtained by Rp. palustris from sugar beet molasses. The yield was comparable to those values obtained in two-stage processes. The present study demonstrates that single-stage photofermentation using purple non-sulfur bacteria on sucrose-based wastes is promising.

Mesophilic and thermophilic photo-hydrogen production from micro-grinded, enzyme-hydrolyzed maize straws

Photo-fermentative is an endothermic reaction driven by light energy to overcome the energy barrier. This communication conducted photo-fermentation hydrogen tests with micro-grinded, enzyme-hydrolyzed maize straws considering the effects of broth temperature ranging 28.2–54.5 °C. The hydrogen production rate was first increased with broth temperature, peaked at 39.6 °C, and then decreased at higher temperature range. The photo-fermentative process can be approximated as a catalytic reaction with positive activation energy and positive activation entropy, an endothermic, entropy-driven complexation process.

Comprehensive modeling of photo-fermentation process for prediction of hydrogen production

Hydrogen production via modern technologies and without using fossil fuels has been found considerably important recently. Photo-fermentation is introduced as one of the most effective methods without high risk for bio-hydrogen production. In this study, comprehensive modeling and simulation of bio-hydrogen production is carried out through photo-fermentation process. In this way, different applicable models are considered to predict the kinetics of microbial growth. Also, new modified mathematical models are particularly proposed for photo-fermentation to forecast the specific growth rate of microorganisms, substrate consumption and hydrogen production rates. Various combinations of the models are applied and predictions of the models are validated by experimental data related to the growth of Rhodobacter Sphaeroides on malate as the substrate. The combination, entitled as MVA1, is introduced as the best one to predict kinetic factors in photo-fermentation. The presented models can be used as an excellent starting point to accomplish experimental and industrial works.

Effect of adding brewery wastewater to pulp and paper mill effluent to enhance the photofermentation process: wastewater characteristics, biohydrogen production, overall performance, and kinetic modeling.

Although a significant amount of brewery wastewater (BW) is generated during beer production, the nutrients in the BW could be reused as a potential bio-resource for biohydrogen production. Therefore, improvements in photofermentative biohydrogen production due to a combination of BW and pulp and paper mill effluent (PPME) as a mixed production medium were investigated comprehensively in this study. The experimental results showed that both the biohydrogen yield and the chemical oxygen demand removal were improved through the combination of BW and PPME. The best biohydrogen yield of 0.69mol H2/L medium was obtained using the combination of 10% BW+90% PPME (10B90P), while the reuse of the wastewater alone (100% BW and 100% PPME) resulted in42.3 and44.0% less biohydrogen yields than the highest yield, respectively. The greatest light efficiency was 1.97% and was also achieved using the combination of both wastewaters at 10B90P. This study revealed the potential of reusing and combining two different effluents together, in which the combination of BW and PPME improved the nutrients and light penetration into the mixed production medium.

A critical review on factors influencing fermentative hydrogen production.

Biohydrogen production by dark fermentation of different waste materials is a promising approach to produce bio-energy in terms of renewable energy exploration. This communication has reviewed various influencing factors of dark fermentation process with detailed account of determinants in biohydrogen production. It has also focused on different factors such as improved bacterial strain, reactor design, metabolic engineering and two stage processes to enhance the bioenergy productivity from substrate. The study also suggest that complete utilization of substrates for biological hydrogen production requires the concentrated research and development for efficient functioning of microorganism with integrated application for energy production and bioremediation. Various studies have been taken into account here, to show the comparative efficiency of different substrates and operating conditions with inhibitory factors and pretreatment option for biohydrogen production. The study reveals that an extensive research is needed to observe field efficiency of process using low cost substrates and integration of dark and photo fermentation process. Integrated approach of fermentation process will surely compete with conventional hydrogen process and replace it completely in future.

ADVANCES IN BIOLOGICAL HYDROGEN PRODUCTION PROCESSES

Biological hydrogen production processes offer a technique through which renewable energy sources like biomass can be utilized for the generation of the cleanest energy carrier for the use of mankind. Hydrogen intensive research work has already been carried out on the advancement of these processes, such as the development of genetically modified microorganism, metabolic engineering, improvement of the reactor designs, use of different solid matrices for the immobilization of whole cells, biochemical assisted bioreactor, development of two-stage processes, etc. for higher H 2 -production rates. Maximum H 2 yield is found to be 7.1 mol H 2 /mol glucose. However, major bottlenecks for the commercialization of these processes are lower H 2 yield and rate of H 2 production. Suitable microbial cultures are required to handle waste materials efficiently, which are usually complex in nature. This will serve dual purposes: clean energy generation and bioremediation. Scale-up studies on fermentative H 2 -production processes have been done successfully. Pilot plant trials of the photo-fermentation processes require more attention. Use of cheaper raw materials and efficient biological hydrogen production processes will surely make them more competitive with the conventional H 2 generation processes in near future.

Photo-fermentative hydrogen production from enzymatic hydrolysate of corn stalk pith with a photosynthetic consortium

Corn stalk pith is a waste product of papermaking from corn stalk, and is easy to digest, which makes it a promising feedstock for biofuel production. The main aim of this study is to evaluate utilization of corn stalk pith for hydrogen production. Corn stalk pith was hydrolyzed with commercial cellulase at 50 °C, and the hydrolysate was used as a carbon source for hydrogen production with a photosynthetic consortium. Effect of initial pH on sugar consumption, hydrogen production and byproducts accumulation was evaluated with initial reducing sugar concentrations of about 11 g/L. Single-factor experiments were conducted to determine optimal conditions. Substrate conversion efficiencies (82–94%) during photo-fermentation at initial pH of 6–9 were higher than those (40–80%) achieved in previous studies on hydrogen production from glucose using the same photosynthetic consortium. Hydrogen yield (2.6 ± 0.3 mol H2/mol sugar consumed) obtained at an initial pH of 7 was higher or comparable to those reported in literatures. During the photo-fermentation process, hydrogen was mainly produced via acetic acid production pathway in the first 24 h, and the butyric acid production pathway dominated the hydrogen production for the next 72 h. It was for the first time that corn stalk pith has been used for hydrogen production.

Ultrasonication pre-treatment of combined effluents from palm oil, pulp and paper mills for improving photofermentative biohydrogen production

The improvement of batch photofermentative biohydrogen production was investigated using ultrasonication pre-treatment on a combined effluent of palm oil and pulp and paper mills. The effects of the amplitude (30–90%) and ultrasonication duration (5–60min) were investigated in terms of their influences on the biohydrogen yield and chemical oxygen demand (COD) removal. The recommended ultrasonication parameters were found at the higher ranges of amplitude and duration (A70T45). Using A70T45 ultrasonication, the production of biohydrogen at 30°C could be enhanced up to 8.72mL H2/mLmedium, with a total COD removal of 36.9%. During pre-treatment at A70T45, an energy input of 775J/mL was supplied to disintegrate complex compounds into simpler structures. As a result, an increase in the soluble organic matter concentration was achieved, which led to enhanced biohydrogen production. On the other hand, the lowest biohydrogen yield (4.67mL H2/mLmedium) and total COD removal (28.8%) were obtained in the control without pre-treatment. The enthalpy of the photofermentation process was estimated to be 141.1kJ/mol with a threshold temperature of 30.9°C based on a modified Arrhenius approach.

Photofermentaion and lipid accumulation by Rhodobacter sp. KKU-PS1 using malic acid as a substrate

Photofermentation and lipid accumulation by the purple non-sulfur photosynthetic bacterium, Rhodobacter sp. KKU-PS1, from malic acid was investigated in batch fermentation. Media compositions including malic acid concentration, glutamate concentration, amount of vitamin addition and Fe concentration were optimized by response surface methodology with central composite design in order to achieve a maximum hydrogen production rate (Rm). The predicted Rm of 11.7 mL H2/L. h was obtained under optimal media compositions of 2.36 g/L malic acid, 224 mg/L glutamate, and 13.5 mL/L of vitamin solution addition along with 64 mg/L of Fe. The cellular lipid content in Rhodobacter sp. KKU-PS1 was checked at the end of photo-fermentative process. A nitrogen limited condition was suitable for lipid accumulation by Rhodobacter sp. KKU-PS1. A maximum lipid production of approximately 592 mg/L was obtained with 4.7 g/L malic acid, 159 mg/L glutamate, 21.7 mL/L of vitamin solution along with 330 mg/L Fe (equivalent to C/N ratio of 132). Triacylglycerol (TAG) was the major component of the lipid in which the predominant fatty acid was octadecanoic acid (C18:1) in the form of oleic acid (C18:1n-9). The physicochemical properties of biodiesel predicted from fatty acid methyl esters (FAMEs) compositions of lipid produced by Rhodobacter sp. KKU-PS1 under the suitable conditions indicated that the lipid produced by the strain KKU-PS1 has a fairly good potential for use as biodiesel.