Effects of volatile fatty acids in biohydrogen effluent on biohythane production from palm oil mill effluent under thermophilic condition

Background: Biohydrogen effluent contains a high concentration of volatile fatty acid (VFA) mainly as butyric, acetic, lactic and propionic acids. The presence of various VFAs (mixture VFAs) and their cooperative effects on two-stage biohythane production need to be further studied. The effect of VFA concentrations in biohydrogen effluent of palm oil mill effluent (POME) on methane yield in methane stage of biohythane production was investigated. Results: The methane yield obtained in low VFA loading (0.9 and 1.8 g/L) was 15­20% times greater than that of high VFA loading (3.6 and 4.7 g/L). Butyric acid at high concentrations (8 g/L) has the individual significantly negative effect the methane production process (P b 0.05). Lactic, acetic and butyric acid mixed with propionic acid at a concentration higher than 0.5 g/L has an interaction significantly negative effect on the methanogenesis process (P b 0.05). Inhibition condition had a negative effect on both bacteria and archaea with inhibited on Geobacillus sp., Thermoanaerobacterium thermosaccharolyticum, Methanoculleus thermophilus and Methanothermobacter delfuvii resulting in low methane yield. Conclusion: Preventing the high concentration of butyric acid, and propionic acid in the hydrogenic effluent could enhance methane production in two-stage anaerobic digestion for biohythane production.

Effect of different solute solutions on hydrogen producing rate of hydrogen rods / 军事医学

Objective To investigate the hydrogen production rate of hydrogen rods in different solute solutions ,and to study the correlations between hydrogen and oxygen concentrations in the solution and the relationships between hydrogen and oxidation-reduction potential .Methods The hydrogen rich solution was produced using metal magnesium to react with water.The experiment was divided into NaCl , Na2SO3, Na2SO4, CH3COOH, and CH3COONa solution groups, respectively, with 0％, 0.2％, 0.9％and 3％in different concentration solutions .The hydrogen content of the corresponding solution was determined at 0, 2, 4, 6, 8, and 10 h.Moreover, the oxygen content in the solution , redox potential and pH value were simultaneously determined .Results Within the same reaction time , the higher concentration of NaCl , the higher the hydrogen production rate .The amount of hydrogen in the solution was negatively correlated with that of oxygen ( R2 =0.9306).The higher the hydrogen content, the lower the oxygen content.With the amount of hydrogen in the solution increasing, oxidation was reduced while pH was increased.The hydrogen-producing rate of hydrogen rods in different solute solutions was the highest with Na2SO3,followed by NaCl and Na2SO4(P<0.05 or P<0.01).In the acetic acid solution, the hydrogen-producing rate of rods was significantly higher than in the sodium salt solution (P<0.05).The hydrogen content increased gradually with time .The oxygen concentration was significantly lower than in the sodium salt solution ( P <0.05), and the oxygen content decreased over time .Conclusion The type and concentration of solutes in solutions and the oxygen content and acidity of a solution have significant influence on the hydrogen -producing rate of hydrogen rods. Therefore, by adjusting the type and concentration of solutes in the solution, we can prepare different types of hydrogen concentration solutions , which can provide detailed reference parameters for hydrogen production of hydrogen rods in clini -cal and practical applications.

Optimization of Hydrogen Production Conditions of Photosynthetic Bacteria Group by Orthogonal Test / 微生物学通报

The influence factors for hydrogen production using photosynthetic bacteria group were studied. The effects of carbon sources, nitrogen sources, carbon concentration, nitrogen concentration, initial pH value, illumination mode and inoculation amount on hydrogen production were investigated by experiment of single factor and orthogonal experiment. The optimum process conditions were as follows: the best bacteria group was number 3, the glucose was carbon source and concentration of carbon source was 3 g/L; the urea was nitrogen source and concentration of nitrogen source was 9 g/L; the inoculation amount was 10%; initial pH value was 8.5; the illumination mode was 12 h light and 12 h dark alternation; incubation temperature was 30?C. The main factors affecting hydrogen production were strain, carbon sources, carbon source concentration and nitrogen suorces.

Characteristic Analysis of Cooperation Hydrogen Production Using Rhodopseudomonas sp. DT and Enterobacter Aerogenes / 微生物学通报

Cooperation hydrogen production was carried out using Rhodopseudomonas sp. DT and Enterobacter aerogenes. The effects of the initial ratio of Rhodopseudomonas sp. DT and E. aerogenes, culture temperature, and carbon source on the cooperation hydrogen production were investigated. The results suggested that cooperation hydrogen production rate was highly affected by the initial ratio of Rhodopseudomonas sp. DT and E. aerogenes. The mixed bacteria of Rhodopseudomonas sp. DT and E. aerogenes with 1:1 initial ratio benefited to the cooperation hydrogen production, which led the hydrogen production rate and duration of gas production to 3.1 mol H2/mol glucose and 81 h, respectively. The pH dynamics analysis of culture medium further discovered that the pH of the mixed bacteria with 1:1 initial ratio changed from 6 to 7 smaller than other conditions, which was probably fitted to produce hydrogen. Furthermore, the mixed bacteria with 1:1 initial ratio had the higher hydrogen production efficiency at temperatures of 28?C and 37?C than at 20?C, and without any hydrogen production at temperature of 50?C. The carbon sources of glucose, succinate acid, malic acid could be used to produce hydrogen by the mixed bacteria. Even the soluble starch, unused by Rhodopseudomonas sp. DT, was also decomposed by the mixed bacteria to produce hydrogen with the conversion efficiency of 8.22%. The glucose was the optimal carbon resource, and the conversion efficiency could reach to 36.11%. The results, further, implied that the cooperation hydrogen production could enlarge the use of the carbon sources.

Research Process of Anaerobic Fermentative Hydrogen Production and Its Development Future / 中国生物工程杂志

Hydrogen is an ideal energy due to its high conversion efficiency, recyclability and nonpolluting nature. Compared with conventional methods, biological hydrogen production process is found to be less energy intensive and more environmental friendly, and nowadays more and more attentions are being paid on its fermentative way. A survey of fermentative bio-hydrogen production process was provided, followed by its new approaches in the future development.

Cloning and Transformation of lba Gene of Glycine max into Chloroplast of Chlamydomonas reinhardtii / 中国生物工程杂志

To decrease the oxygen content in the cell is a key method to improve hydrogen production in Chlamydomonas reinhardtii.A new approach was developed by transforming the leghemoglobin gene lba,which has high affinity to oxygen,into the chloroplast of C.reinhardtii to get a low dissolved oxygen in the cell and result into improvement of H2 ase activity and H2 yield. The results showed that lba was successfully transformed into the chloroplast of C.reinahrdtii strain 849 and did not affect its growth significantly. The work paved the road for further regulation of lba expression in the chloroplast to improve of hydrogen production of C.reinahrdtii.

Effect of Initial Substrate Concentration on Kinetics of Hydrogen Production by Photosynthetic Bacteria in Batch Culture / 中国生物工程杂志

The effect of initial substrate concentration on the growth,metabolic activities of Photosynthetic bacteria (PSB) in the process of hydrogen production is studied.The empirical relation of the initial substrate concentration to the specific growth rate,specific substrate consumption rate and specific hydrogen production rate of PSB are developed based on the modified Monod model.It is found that the results given by the model are well agreed with the experimental data in growth phase and stationary phase of PSB.Meanwhile,the optimal substrate concentration in the process of growth,metabolism and hydrogen production is 50 mmol/L.Furthermore,when the initial substrate concentration deviates 50 mmol/L,the activation of PSB is limited or inhibited,and the inhibiting effect is more prominent than the limiting effect.In addition,it is demonstrated that initial substrate concentration has little effect on the specific substrate consumption rate.

Photoproduction of hydrogen by photosynthetic bacteria from sewage and waste water.

Numerous prokaryotes, belonging to physiologically and taxonomically different groups, are able to produce hydrogen. Some photosynthetic bacteria have the property of light-dependent production of hydrogen from organic substrates. We isolated several photosynthetic purple and green bacteria from enrichment cultures made from the water of a waste-water pond of a cool-drink refilling station. After testing them for their ability to use various organic compounds as carbon source, and sulphide, thiosulphate and organic compounds as electron donor, we selected the fastest-growing isolate, a Rhodopseudomonas, for a study of its ability to produce molecular hydrogen in presence of light. Immobilized cells of this isolate produced significant amounts of hydrogen from both sewage and waste water.

Factors of Affecting Mcrobial Fermentative Hydrogen Production / 微生物学通报

As a clean, efficient, and renewable energy, hydrogen is regarded as a promising alternative. Because of using biomass as substrate, microbial fermentative hydrogen production can meet the need of sustainable development. The factors affecting the process of microbial fermentative hydrogen production, are analyzed in this paper on the basis of microorganisms, substrates, products and operative parameters. The parameters related to hydrogen production from organic wastes, are also mentioned.

Fermentative Hydrogen Production with Xylose by Clostridium sp. HR-1 Isolated from Cow Dung Compost / 微生物学通报

A anaerobic hydrogen-producing strain HR-1 was isolated from compost. Phylogenetic analysis based on 16S rRNA sequence similarity indicates that strain HR-1 is the closest relative to Clostridium ace- tobutylicum ATCC 824, with the similarity of 96%. Biological characteristics and phylogenetic analysis of 16S rRNA gene indicate that HR-1 is a new species named Clostridium sp. HR-1. Cells are Gram-positive, mobile rod-shaped. Spores and flagellums were no observed. Temperature range for growth is 10?C to 45?C (optimum temperature 37?C~39?C), and range pH for growth is 4.0 to 10.0 (optimum pH 7.5~8.0). H2, CO2, acetate, butyrate and a little ethanol are the end products of PYG fermentation. Strain HR-1 has the ability to use organic nitrogen and inorganic nitrogen sources for growth and hydrogen production, and yeast extract is the optimum nitrogen source for hydrogen production. Strain HR-1 produces hydrogen from xylose (3 g/L) at 37?C and initial pH 6.5, the hydrogen yields and maximal hydrogen production rate are 1.84 mol-H2/mol-xylose and 10.52 mmol-H2/h?g-cdw, respectively. Strain HR-1 is able to utilize glucose, galactose, fructose, mannose and cellobiose for hydrogen production and the hydrogen yields from glucose is 2.36 mol-H2/mol-glucose.

Combined Mutation Breeding of H_2-producing Strain and Hydrogen Producing Characterization of a H_2-producing Mutant HCM-23 / 微生物学通报

The fermentative H2-producing strain Clostridium sp. H-61 was isolated from anaerobic sludge,was used as an original strain which was induced by NTG and UV for increasing and the hydrogen production ability. One of the highest efficient H2-producing mutants was named as HCM-23 with its stable hydrogen production ability. which was measured in the batch culture experiments. With the condition of 10 g/L glucose,its cumulative hydrogen yield and hydrogen production rate was 3024 mL/L and 33.19 mmol H2/g DW?h,69.89% and 68.14% higher than that of the original strain,respectively. The terminal liquid product compositions showed that the mutant HCM-23 fermentation was ethanol type,while the original strain H-61 fermentation was butyric acid type. Varieties of parameters of hydrogen production fermentation studied,including time,carbon source,nitrogen source,glucose concentration,glucose utilization,initial pH and incubation temperature had been studied,indicated the optimum condition of hydrogen production for the mutantHCM-23 as initial pH 6.5,temperature 36 ℃,and the favorite substrate was sucrose. The hydrogen production characters of the mutant and the original strain were different,such as,the growth lag phase and the utilization of inorganic nitrogen source,etc. This work shows a good application potential of NTG-UV combined mutation in the biohydrogen production. And the hydrogen production mechanism and metabolic pathway should be explored furthermore.

Hydrogen Production by Chromatium vinosum with Fermentation Waste Produced by Klebsiella oxytoca / 微生物学通报

Photosynthetic bacteria(PSB) showed great promise in biohydrogen production. Chromatium vinosum was able to utilize the fermentation waste of Klebsiella oxytoca for both photo-fermentative and dark-fermentative hydrogen production. The content of residual sugars and main organic acids decreased obviously after hydrogen production by C.vinosum. The maximal hydrogen production of C.vinosum was obtained at pH 6.5 adding extra 0.1%(W/W) NH_4Cl. Under photo-fermentative conditions, the content of butyric acid decreased by 54.38%, and the maximal hydrogen yield was 36.97 mL/mg cell. Under dark-fermentative conditions, the content of butyric acid decreased by 36.1% and the maximal hydrogen production was achieved as 37.50 mL/mg cell.