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1.
One-factor-at-a-time design and orthogonal design were used in the experimental design methods to optimize bio-hydrogen (bio-H2) production from cornstalk wastes by anaerobic fermentation. Three series of experiments were designed to investigate the effects of substrate concentration, initial pH and orthogonal design on the bio-H2 production by using the natural sludge as inoculant. Experimental results indicate that substrate concentration was the most significant condition for optimal hydrogen production. The optimum orthogonal design method was proposed to be at an enzymatic temperature of 50 °C, an enzymatic time of 72 h, an initial pH of 7.0 and a substrate concentration of 10 g/L. The proposed method facilitated the optimization of optimum design parameters, only with a few well-defined experimental sets. Under the proposed condition, the maximum cumulative H2 yield was 141.29 ml g?1-CS (cornstalk, or 164.48 ml g?1-TS, total solid, TS = 0.859 Wdried cornstalk), with an average H2 production rate of 12.31 ml g?1-CS h?1. The hydrogen content reached 57.85% and methane was not detected in the biogas.  相似文献   

2.
Ground wheat powder solution (10 g L−1) was subjected to combined dark and light fermentations for bio-hydrogen production by fed-batch operation. A mixture of heat treated anaerobic sludge (AN) and Rhodobacter sphaeroides-NRRL (RS-NRRL) were used as the mixed culture of dark and light fermentation bacteria with an initial dark/light biomass ratio of 1/2. Effects of wheat starch loading rate on the rate and yield of bio-hydrogen formation were investigated. The highest cumulative hydrogen formation (CHF = 3460 ml), hydrogen yield (201 ml H2 g−1 starch) and formation rate (18.1 ml h−1) were obtained with a starch loading rate of 80.4 mg S h−1. Complete starch hydrolysis and glucose fermentation were achieved within 96 h of fed-batch operation producing volatile fatty acids (VFA) and H2. Fermentation of VFAs by photo-fermentation for bio-hydrogen production was most effective at starch loading rate of 80.4 mg S h−1. Hydrogen formation by combined fermentation took place by a fast dark fermentation followed by a rather slow light fermentation after a lag period.  相似文献   

3.
An anaerobic fermentation process to produce hydrogen from cornstalk wastes was systematically investigated in this work. Batch experiments numbered series I, II and III were designed to investigate the effects of acid pretreatment, enzymatic hydrolysis (enzymatic temperature, enzymatic time and enzymatic pH) on hydrogen production by using the natural sludge as inoculant. A maximum cumulative H2 yield of 126.22 ml g−1-CS (Cornstalk, or 146.94 ml g−1-TS, Total Solid) and an average H2 production rate of 9.58 ml g−1-CS h−1 were obtained from fermentation cornstalk with a concentration of 20 g/L and an initial pH of 7.0 at 36 °C through an optimal pretreatment process. The optimal process was that the substrate was soaked with an HCl concentration of 0.6 wt% at 90 °C for 2 h, and subsequently enzymatic hydrolysis for 72 h at 50 °C and pH 4.8 before fermentation. The biogas consisted of only H2 and CO2. In addition, the fermentation system was the typical ethanol-type fermentation according to ethanol and acetate as the main liquid by-products.  相似文献   

4.
In this paper, the high concentration of corn stalk (60 g/L) was employed as feedstock to produce bio-hydrogen and methane by combining hydrogen fermentation and anaerobic digestion. In the first stage of hydrogen fermentation, the effects of several key parameters, such as strain enhancement technique, cetyl trimethyl ammonium bromide (CTAB), NH4HCO3 on hydrogen production from cornstalk were investigated and optimized. The maximum hydrogen yield of 79.8 ± 1.5 ml H2/g-TS and hydrogen production rate of 3.78 ml/g-cornstalk h was observed at fixed acidizing cornstalk of 60 g/L, strains Bacillus sp. FS2011 dosage of 10%(v/v), CTAB of 30 mg/L, NH4HCO3 of 1.2 g/L and initial pH of 7.5 ± 0.5 at 36 ± 1 °C, respectively. In the second stage of anaerobic digestion, the effluent from hydrogen production bio-reactor was further employed as the feedstock to produce methane by methanogenic bacteria, the maximum methane yield of 227 ± 2.5 ml CH4/g-COD and COD removal rate of 95  ± 1% was recorded. The interesting observations were that the total amount of the organic wastewater produced in a higher substrate concentration (60 g/l) by hydrogen fermentation was reduced by about two-thirds compared with that of traditional low substrate concentration (≤20 g/l).  相似文献   

5.
Three different pre-treatment methods were applied on two different anaerobic sludge cultures and their mixtures in order to investigate the effects of pre-treatment methods on bio-hydrogen production from dark fermentation of waste ground wheat solution. Repeated heat, chloroform and combinations of heat and chloroform pre-treatment methods were applied to anaerobic sludges from different sources. Repeated heat treatment (2 × 5 h) was found to be more effective in selecting hydrogen producing bacteria compared to the other treatment methods tested on the basis of cumulative hydrogen production. The highest hydrogen formation (652 ml) and specific hydrogen production rate (SHPR = 25.7 ml H2 g−1 cells h−1) were obtained with the anaerobic sludge pre-treated by repeated boiling. Both the type of anaerobic sludge and the pre-treatment method had considerable effects on bio-hydrogen production from wheat powder solution (WPS) by dark fermentation.  相似文献   

6.
Dark fermentation experiments were performed for bio-hydrogen production from ground wheat starch solution (10 ± 1 g l−1) using periodic feeding and effluent removal. A mixed culture of Clostridium butyricum-NRRL 1024 and Clostridium pasteurianum-NRRL B-598 were used with an initial biomass ratio of 1/1.Effects of wheat starch loading rate on the rate and yield of bio-hydrogen formation were investigated. Substrate loading rate was varied between 0.54 and 5.52 g d−1 (HRT = 6-60 h). The highest hydrogen formation rate (280 ml d−1), volumetric hydrogen formation rate (1857 ml H2 l−1 d−1) and volatile fatty acids (VFAs) concentration were obtained with a substrate loading rate of 5.52 g d−1 (HRT = 6 h). The highest hydrogen yield (109 ml H2 g TS −1) was obtained with a substrate loading rate of 1.38 g d−1.  相似文献   

7.
Hydrogen formation performances of different anaerobic bacteria were investigated in batch dark fermentation of waste wheat powder solution (WPS). Serum bottles containing wheat powder were inoculated with pure cultures of Clostridium acetobutylicum (CAB), Clostridium butyricum (CB), Enterobacter aerogenes (EA), heat-treated anaerobic sludge (ANS) and a mixture of those cultures (MIX). Cumulative hydrogen formation (CHF), hydrogen yield (HY) and specific hydrogen production rate (SHPR) were determined for every culture. The heat-treated anaerobic sludge was found to be the most effective culture with a cumulative hydrogen formation of 560 ml, hydrogen yield of 223 ml H2 g−1 starch and a specific hydrogen production rate of 32.1 ml H2 g−1 h−1.  相似文献   

8.
As a renewable energy source bio-hydrogen production from lignocellulosic wastes is a promising approach which can produce clean fuel with no CO2 emissions. Utilization of agro-industrial residues in solid state fermentation (SSF) is offering a solution to solid wastes disposal and providing an economical process of value-added products such as hydrogen.In this study three different particle size of rice husk (<2000 μm, <300 μm, <74 μm) was subjected to batch SSF with a Clostridium termitidis: Clostridium intestinale ratio of 5:1. C. termitidis is a cellulolytic microorganism that has the ability to hydrolyze cellulosic substances and C. intestinale is able to grow on glucose having a potential of enhancing hydrogen production when used in the co-culture. 5 g dw rice husk with 75% humidity was used as substrate in SSF under mesophilic conditions. The highest HF Volume (29.26 mL) and the highest yield (5.9 mL H2 g−1 substrate) were obtained with the smallest particle size (<74 μm). The main metabolites obtained from the fermentation media were acetic, butyric, propionic and lactic acids. The second best production yield (3.99 mL H2 g−1 substrate) was obtained with the middle particle size (<300 μm) rice husk with a HF of 19.71 mL.  相似文献   

9.
Dark fermentation of acid hydrolyzed ground wheat starch for bio-hydrogen production by periodic feeding and effluent removal was investigated at different feeding intervals. Ground wheat was acid hydrolyzed at pH = 3 and T = 121 °C for 30 min using an autoclave. The resulting sugar solution was subjected to dark fermentation with periodic feeding and effluent removal. The feed solution contained 9 ± 0.5 g L−1 total sugar supplemented with some nutrients. Depending on the feeding intervals hydraulic residence time (HRT) was varied between 6 and 60 h. Steady-state daily hydrogen production increased with decreasing HRT. The highest daily hydrogen production (305 ml d−1) and volumetric hydrogen production rate (1220 ml H2 L−1 d−1) were obtained at HRT of 6 h. Hydrogen yield (130 ml H2 g−1 total sugar) reached the highest level at HRT = 24 h. Effluent total sugar concentration decreased, biomass concentration and yield increased with increasing HRT indicating more effective sugar fermentation at high HRTs. Dark fermentation end product profile shifted from acetic to butyric acid with increasing HRT. High acetic/butyric acid ratio obtained at low HRTs resulted in high hydrogen yields.  相似文献   

10.
The present study focused on the mesophilic anaerobic bio-hydrogen production from PPS (pulp & paper sludge) and FW (food waste), and the subsequent anaerobic digestion of the effluent for the methane production under thermophilic conditions by a two-stage process. The maximum hydrogen yield of 64.48 mL g−1 VSfed and methane yield of 432.3 mL g−1 VSfed were obtained when PPS and FW were applied with 1: 1 VS ratio as the feedstock. No VFA were cumulated in the reactor during the period of hydrogen - methane fermentation, as well as no NH3–N and Na+ inhibition were found in the process. 71%–87% removal efficiencies of SCOD were attained for hydrogen and methane co-production. pH 4.8–6.4 and alkalinity 794–3316 mg CaCO3 L−1 for H2 fermentation, as well as pH 6.5–8.8 and alkalinity 4165–4679 mg CaCO3 L−1 for CH4 fermentation, were achieved without any adjustment. This work showed that anaerobic co-digestion of PPS and FW for hydrogen-methane co-production was a stable, reliable and effective way for energy recovery and bio-solid waste stabilization by the two-stage mesophilic–thermophilic process.  相似文献   

11.
The conversion of ethanol from paper sludge using the separate hydrolysis and fermentation (SHF) process with cellulase and Saccharomyces cerevisiae GIM-2 were investigated in this paper. Optimization strategy based on statistical experimental designs was employed to enhance degree of saccharification by enzymatic hydrolysis of paper sludge. Based on the Plackett-Burman design, hydrolysis time, substrate concentration and cellulase dosage were selected as the most significant variable on the degree of saccharification. Subsequently, the optimum combination of the selected factors was investigated by a Box-Behnken approach. A mathematical model was developed to show the effects of each factor and their combinatorial interactions on the degree of saccharification. The optimal conditions were hydrolysis time 82.7 h, substrate concentration 40.8 g L−1 and cellulase dosage 18.1 FPU g−1 substrate, and a degree of saccharification of 82.1% can be achieved. When hydrolysate was further fermented with S. cerevisiae GIM-2, the conversion rate of sugar to ethanol was 34.2% and the ethanol yield was 190 g kg−1 of dry paper sludge, corresponding to an overall conversion yield of 56.3% of the available carbohydrates on the initial substrate. The results derived from this study indicate that the response surface methodology is a useful tool for optimizing the hydrolysis conditions to converse paper sludge to ethanol.  相似文献   

12.
Ground wheat solution was used for bio-hydrogen production by dark fermentation using heat-treated anaerobic sludge in a completely mixed fermenter operating in fed-batch mode. The feed wheat powder (WP) solution was fed to the anaerobic fermenter with a constant flow rate of 8.33 mL h−1 (200 mL d−1). Cumulative hydrogen production, starch utilization and hydrogen yields were determined at three different WP loading rates corresponding to the feed WP concentrations of 10, 20 and 30 g L−1. The residual starch (substrate) concentration in the fermenter decreased with operation time while starch consumption was increasing. The highest cumulative hydrogen production (3600 mL), hydrogen yield (465 mL H2 g−1 starch or 3.1 mol H2 mol−1 glucose) and hydrogen production rate (864 mL H2 d−1) were obtained after 4 days of fed-batch operation with the 20 g L−1 feed WP concentration corresponding to a WP loading rate of 4 g WP d−1. Low feed WP concentrations (10 g L−1) resulted in low hydrogen yields and rates due to substrate limitations. High feed WP concentrations (30 g L−1) resulted in the formation of volatile fatty acids (VFAs) in high concentrations causing inhibition on the rate and yield of hydrogen production.  相似文献   

13.
A strategic method utilizing the co-culture of Clostridium thermocellum and Clostridium thermosaccharolyticum has been developed to improve hydrogen production via the thermophilic fermentation of cornstalk waste. The hydrogen yield in the co-culture fermentation process reached 68.2 mL/g-cornstalk which was 94.1% higher than that in the mono-culture. The hydrogen fermentation process was successfully scaled-up from 125 mL anaerobic bottles to an 8 L continuous stirred tank reactor, and the hydrogen production from cornstalk waste was significantly improved in the bioreactor system due to efficient mixing and mass transfer. The hydrogen yield in the bioreactor reached 74.9 mL/g-cornstalk which was 9.8% higher than that in the 125 mL anaerobic bottle. The present work indicates that the direct microbial conversion of lignocellulosic waste by co-culturing C. thermocellum and C. thermosaccharolyticum is a promising avenue for enhancing hydrogen production.  相似文献   

14.
Batch dark fermentation experiments were performed to investigate the effects of biomass and substrate concentration on bio-hydrogen production from acid hydrolyzed ground wheat at 55 °C. In the first set of experiments, the substrate concentration was constant at 20 g total sugar L−1 and biomass concentration was varied between 0.52 and 2.58 g L−1. Total sugar concentration was varied between 4.2 and 23.7 g L−1 in the second set of experiments with a 1.5 g L−1 constant biomass concentration. The highest cumulative hydrogen formation (582 mL, 30 °C, 1 atm), formation rate (5.43 mL h−1) and final total volatile fatty acid (TVFA) concentration (6.54 g L−1) were obtained with 1.32 g L−1 biomass concentration. In variable substrate concentration experiments, the highest cumulative hydrogen (365 mL) and TVFA concentration (4.8 g L−1) were obtained with 19.25 g L−1 initial total sugar concentration while hydrogen gas formation rate (12.95 mL h−1) and the yield (200 mL H2 g−1 total sugar) were the highest with 4.2 g L−1 total sugar concentration.  相似文献   

15.
《Biomass & bioenergy》2007,31(4):250-254
Biohydrogen production from the cornstalk wastes with acidification pretreatment was reported in this paper. Batch tests were carried out to analyze influences of several environmental factors on biohydrogen production from cornstalk wastes. Two predominant bacterial morphologies, namely spore-forming rod shape bacteria and micrococcus were screened, purified, and identified after enriched from a hydrogen-producing fermentor with cow dung composts. The maximum cumulative H2 yield of 149.69 ml H2 g−1 TVS was obtained at initial pH 7.0 and substrate concentration 15 g l−1, the value is about 46-fold as compared with that of raw cornstalk wastes. The maximum hydrogen production rate was 7.6 ml H2 h−1. The hydrogen concentration in biogas was 45–56% (v/v) and there was no significant methane observed in the biogas throughout this study. In addition, biodegradation characteristics of the substrate by microorganisms were also discussed. During the conversion of cornstalk wastes into hydrogen, the acetate, propionate, butyrate, and the ethanol were main by-products in the metabolism of hydrogen fermentation. The test results showed that the acidification pretreatment of the substrate plays a crucial role in conversion of the cornstalk wastes into biohydrogen gas by the cow dung composts generating hydrogen.  相似文献   

16.
A two-step process of sequential anaerobic (dark) and photo-heterotrophic fermentation was employed to produce hydrogen from cassava and food waste. In dark fermentation, the average yield of hydrogen was approximately 199 ml H2 g−1 cassava and 220 ml H2 g−1 food waste. In subsequent photo-fermentation, the average yield of hydrogen from the effluent of dark fermentation was approximately 611 ml H2 g−1 cassava and 451 ml H2 g−1 food waste. The total hydrogen yield in the two-step process was estimated as 810 ml H2 g−1 cassava and 671 ml H2 g−1 food waste. Meanwhile, the COD decreased greatly with a removal efficiency of 84.3% in cassava batch and 80.2% in food waste batch. These results demonstrate that cassava and food waste could be ideal substrates for bio-hydrogen production. And a two-step process combining dark fermentation and photo-fermentation was highly improving both bio-hydrogen production and removal of substrates and fatty acids.  相似文献   

17.
The fermentation of glucose, cheese whey and the mixture of glucose and cheese whey were evaluated in this study from two inocula sources (sludge from a UASB reactor for swine wastewater treatment and poultry slaughterhouse) for hydrogen production in continuous anaerobic fluidized bed reactors (AFBR). For all fermentations, a hydraulic retention time (HRT) of 6 h and a substrate concentration of 5 g COD L−1 were used. In glucose fermentation, the maximum hydrogen yield (HY) was 1.37 mmol H2 g−1 COD. The co-fermentation of the cheese whey and glucose mixture was favorable for the concomitant production of hydrogen and ethanol, with yields of up to 1.7 mmol H2 g−1 COD and 3.45 mol EtOH g−1 COD in AFBR2. The utilization of cheese whey as a sole substrate resulted in an HY of 1.9 mmol H2 g−1 COD. Throughout the study, ethanol fermentation was evident.  相似文献   

18.
This study addressed the utilization of an agro-waste, corn stover, as a renewable lignocellulosic feedstock for the fermentative H2 production by the moderate thermophile Thermoanaerobacterium thermosaccharolyticum W16. The corn stover was first hydrolyzed by cellulase with supplementation of xylanase after delignification with 2% NaOH. It produced reducing sugar at a yield of 11.2 g L−1 glucose, 3.4 g L−1 xylose and 0.5 g L−1 arabinose under the optimum condition of cellulase dosage 25 U g−1 substrate with supplement xylanase 30 U g−1 substrate. The hydrolyzed corn stover was sequentially introduced to fermentation by strain W16, where, the cell density and the maximum H2 production rate was comparable to that on simulated medium, which has the same concentration of reducing sugars with hydrolysate. The present results suggest a promising combined hydrogen production process from corn stover with enzymatic hydrolysis stage and fermentation stage using W16.  相似文献   

19.
Pectinase and cellulase enzymes were used for hydrolysis of whole sugar beets and the hydrolyzates were fermented with Escherichia coli KO11 and Saccharomyces cerevisiae via simultaneous saccharification and fermentation (SSF). Ethanol production rate was significantly higher for S. cerevisiae than for E. coli KO11. The combined effect of pectinase and cellulase loadings on ethanol production as well as residual galacturonic acid and arabinose concentrations were modeled for fermentations with S. cerevisiae. Ethanol yields of more than 92% were reached with moderate to high cellulase and pectinase loadings at 0.51 FPU g−1 and 51 U g−1 of dry biomass, respectively. Ethanol yields of 85% were achieved without any enzyme addition. However, addition of cellulase and pectinase enzymes increased effluent arabinose and galacturonic acid concentrations and reduced total suspended solids. This study demonstrated the yield potential of fermentation of crushed, whole sugar beets with or without the addition of cellulase and pectinase enzymes.  相似文献   

20.
Sulfate-reducing bacteria (SRB) have an extremely high hydrogenase activity and in natural habitats where sulfate is limited, produce hydrogen fermentatively. However, the production of hydrogen by these microorganisms has been poorly explored. In this study we investigated the potential of SRB for H2 production using the model organism Desulfovibrio vulgaris Hildenborough. Among the three substrates tested (lactate, formate and ethanol), the highest H2 production was observed from formate, with 320 mL L−1medium of H2 being produced, while 21 and 5 mL L−1medium were produced from lactate and ethanol, respectively. By optimizing reaction conditions such as initial pH, metal cofactors, substrate concentration and cell load, a production of 560 mL L−1medium of H2 was obtained in an anaerobic stirred tank reactor (ASTR). In addition, a high specific hydrogen production rate (4.2 L g−1dcw d−1; 7 mmol g−1dcw h−1) and 100% efficiency of substrate conversion were achieved. These results demonstrate for the first time the potential of sulfate reducing bacteria for H2 production from formate.  相似文献   

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