Thermophilic Biohydrogen Research Articles

Mesophilic and Thermophilic Biohydrogen Production from Xylose at Various Initial pH and Substrate Concentrations with Microflora Community Analysis

Anaerobic dark fermentation biohydrogen production from xylose was investigated under mesophilic (35 °C) and thermophilic (55 °C) conditions at various initial pH (5.0–10.0) and substrate concentrations (2.5–12.5 g/L). In addition, the microbial community structure variations under different temperatures were analyzed. It was demonstrated that the maximum hydrogen yield (1.24 mol-H2/mol-xylose) was obtained with substrate concentration of 7.5 g/L and initial cultivation, pH 7.0, at 35 °C, with butyrate, acetate, and ethanol as the major byproducts. The increase of substrate concentration resulted in accumulation of volatile fatty acids (VFAs), especially propionate, and a decrease in final pH under mesophilic conditions. However, the hydrogen yield increased along with the increase of substrate concentration at 55 °C with butyrate and ethanol as the main metabolite. Stable pH of the system could be maintained even at high xylose concentration up to 12.5 g/L due to a low level of VFAs accumulation. A lower...

Thermophilic biohydrogen production for commercial application: the whole picture

Thermophilic biohydrogen production for commercial application: the whole picture

Thermophilic bio-hydrogen production from corn-bran residue pretreated by calcined-lime mud from papermaking process

This study investigated the use of calcined-lime mud from papermaking process (CLMP) pretreatment to improve fermentative hydrogen yields from corn-bran residue (CBR). CBR samples were pretreated with different concentrations (0–15g/L) of CLMP at 55°C for 48h, prior to the thermophilic fermentation with heat-treated anaerobic sludge inoculum. The maximum hydrogen yield (MHY) of 338.91ml/g-VS was produced from the CBR pretreated with 10g/L CLMP, with the corresponding lag-phase time of 8.24h. Hydrogen yield increments increased from 27.76% to 48.07%, compared to the control. The CLMP hydrolyzed more cellulose, which provided adequate substrates for hydrogen production.

Long-term effect of acid and heat pretreatment of sludge from a sugarcane vinasse treatment plant on the microbial community and on thermophilic biohydrogen production

This work investigated how heat and acid pretreatment affected thermophilic biohydrogen production by a mixed culture present in the sludge of a sugarcane vinasse treatment plant. Heat- (80 °C for 15 min) or acid- (pH 3 for 24 h) treated sludge samples were employed to seed batch bioreactors along 36 days. The heat- and acid-treated sludge samples afforded H2 production rates (HPRs) of 8.4 and 9.5 mmol/L.d, respectively. The lactic acid concentration increased in the bioreactor seeded with heat-treated sludge, whilst the lactic acid concentration diminished in the bioreactor inoculated with the acid-treated sludge. Identification of the microbial community revealed that Clostridiaceae predominated in all the sludge samples. The most abundant Clostridiaceae in the heat- and acid-treated sludge samples were Clostridium and Thermoanaerobacterium, respectively. Acid pretreatment modified the microbial community and enhanced consumption of lactic acid, a metabolite that is normally associated with decreased H2 production.

Performance of mesophilic biohydrogen-producing cultures at thermophilic conditions

In this study, batch tests were conducted to investigate the performance of mesophilic anaerobic digester sludge (ADS) at thermophilic conditions and estimate kinetic parameters for co-substrate fermentation. Starch and cellulose were used as mono-substrate and in combination as co-substrates (1:1 mass ratio) to conduct a comparative assessment between mesophilic (37°C) and thermophilic (60°C) biohydrogen production. Unacclimatized mesophilic ADS responded well to the temperature change. The highest hydrogen yield of 1.13mol H2/mol hexose was observed in starch-only batches at thermophilic conditions. The thermophilic cellulose-only yield (0.42mol H2/mol hexose) was three times the mesophilic yield (0.13mol H2/mol hexose). Interestingly, co-fermentation of starch–cellulose at mesophilic conditions enhanced the hydrogen yield by 26% with respect to estimated mono-substrate yields, while under thermophilic conditions no enhancement in the overall yield was observed. Interestingly, the estimated overall Monod kinetic parameters showed higher rates at mesophilic than thermophilic conditions.

Thermophilic biohydrogen production using a UASB reactor: performance during long‐term operation

AbstractBACKGROUNDThe efficiency of H2 production by dark fermentation described in the literature is around 50% of the maximum theoretical value and the experiments are mostly carried out over short‐term operations. This present study evaluated H2 production in a UASB (upflow anaerobic sludge blanket) reactor operated at 55 °C for 366 days using a synthetic substrate based on sucrose. The reactor response to an increased organic loading rate (OLR) was assessed by applying three different hydraulic retention times (HRTs): 12 h (211 days), 6 h (71 days), and 2 h (84 days).RESULTSCH4 was observed in the biogas during startup. The highest average values of the molar H2 flow rate (MHFR), volumetric H2 production rate (VHPR), and H2 yield (HY) were achieved at a HRT of 2 h, and were, respectively, 14.00 ± 5.24 mmol h−1, 75.33 ± 24.65 mL H2 L−1.h−1, and 1.73 ± 1.14 mol–H2 mol‐suc−1. Considering only the unstable steady‐state period, HY average at a HRT of 2 h was 2.56 ± 0.84 mol–H2 mol‐suc−1.CONCLUSIONOperational conditions were found to be the main factors responsible for removing methanogenic microorganisms from the system. Increase in the OLR enhanced H2 production and the ethanol pathway proved to be favorable for H2 production. © 2015 Society of Chemical Industry

Physicochemical characteristics of attached biofilm on granular activated carbon for thermophilic biohydrogen production

In this study, thermophilic biohydrogen production by a mixed culture, obtained from a continuous acidogenic reactor treating palm oil mill effluent, was improved by using granular activated carbon (GAC) as the support material.

Continuous thermophilic biohydrogen production in packed bed reactor

The present research work deals with the performance of packed bed reactor for continuous H2 production using cane molasses as a carbon source. Maximum H2 production rate of 1.7LL−1h−1 was observed at a dilution rate and recycle ratio of 0.8h−1 and 0.6, respectively which was corresponding to the lowest NADH/NAD+ ratio. This suggests that the utilization of NADH pool for H2 and metabolite production might lead to decrement in NADH/NAD+ ratio. Thus NADH/NAD+ ratio show inverse relation with hydrogen production. The substrate degradation kinetics was investigated as a function of flow rate considering the external film diffusion model. At a flow rate of 245mLh−1, the contribution of external film mass transfer coefficient and first order substrate degradation constant were 55.4% and 44.6% respectively. Recycle ratio of 0.6 improved the hydrogen production rates by 9%. The viable cell count was directly proportional to the recycle ratio (within the range 0.1–0.6). Taguchi design showed the significant influence of the feed pH on continuous H2 production followed by dilution rate and recycle ratio. Thus environmentally friendly and cheaper solid matrix like coconut coir could be efficiently used for thermophilic continuous hydrogen production.

Co-digestion of oil palm trunk hydrolysate with slaughterhouse wastewater for thermophilic bio-hydrogen production by Thermoanaerobacterium thermosaccharolyticm KKU19

The key factors influencing a co-digestion of the oil palm trunk (OPT) hydrolysate with a slaughterhouse wastewater (SHW) to produce hydrogen by Thermoanaerobacterium thermosaccharolyticum KKU19 were investigated. The OPT hydrolysate was obtained by the hydrolysis of OPT by microwave-H2SO4 method using 1.56% (w/v) H2SO4 and 7.50 min reaction time at 450 W. The Plackett–Burman method was used to screen the key factors that influenced the hydrogen production potential (Ps). Results indicated that initial cell concentration, tCOD/TN (total COD/total nitrogen) ratio and CuSO4 concentration influenced the Ps. These factors were further optimized using response surface methodology (RSM) with central composite design (CCD). A maximum Ps of 2604 ± 86 mL H2/L substrate was achieved at an initial cell concentration of 224 mg dry cell/L, tCOD/TN ratio of 49.87 and CuSO4 concentration of 13.33 mg/L. The main soluble metabolite products were butyric and acetic acids. The Ps obtained when the hydrolysate was supplemented with SHW (2604mL ± 86 mL H2/L substrate) was comparable to the Ps obtained when it was supplemented with yeast extract at the same tCOD/TN (2802 ± 87 mL H2/L substrate). This result suggests that SHW can be used to replace the costly nitrogen source.

Thermophilic Fermentative Biohydrogen Production From Xylan by Anaerobic Mixed Cultures in Elephant Dung

Thermophilic bio-hydrogen production from xylan by anaerobic mixed cultures in elephant dung was conducted. The initial pH, temperature, and xylan concentration of 7.0, 55°C and 3.0 g/L, respectively, gave a respective maximum hydrogen yield (HY) and hydrogen production rate (HPR) of 12.16 mmol H2/g xylan and 61.30 mL H2/L.d. The optimum conditions were used to produce hydrogen from sugarcane bagasse (SCB) in which an HY of 2.60 mmol H2/g SCB and a HPR of 59.78 mL H2/L.d were obtained. The hydrogen producers present in both xylan and SCB fermentation broth were Thermoanaerobacterium thermosaccharolyticum and Clostridium sp.

Thermophilic biohydrogen production using pre-treated algal biomass as substrate

Algal biomass is rich in carbohydrates which can be utilized as a promising source of substrate for dark fermentation. It becomes more significant when biomass is produced by capturing atmospheric greenhouse gas, CO2. In the present study, clean energy was generated in the form of biohydrogen utilizing algal biomass. Biohydrogen production was carried out by thermophilic dark fermentation using mixed culture. The culture of Chlorella sorokiniana was cultivated in helical airlift photobioreactor at 30 °C under continuous light intensity of 120 μmol m−2 s−1 provided by white fluorescent lamps. Biomass reached to stationary phase on 9th day giving maximum dry cell weight of 2.9 kg m−3. Maximum carbohydrate and protein content observed was 145 g kg−1 and 140 g kg−1, respectively. Maximum volumetric productivity of 334 g dm−3 d−1 was observed. Algal biomass was subjected to various physical and chemical pre-treatments processes for the improvement of hydrogen production. It was observed that the pretreatment with 200 dm3 m−3 HCl-heat was most suitable pretreatment method producing cumulative hydrogen of 1.93 m3 m−3 and hydrogen yield of 958 dm3 kg−1 volatile suspended solid or 2.68 mol mol−1 of hexose. Growth kinetics parameters such as μmax and Ks were estimated to be 0.44 h−1 and 120 g m−3, respectively. The relationship between biomass and hydrogen production was simulated by the Luedeking–Piret model showing that H2 production is growth associated. The study thus showed the potential of algal biomass as substrate for biological hydrogen production.

Biohydrogen Production under Thermophilic Condition from Ozonated Palm Oil Mill Effluent

Palm oil mill effluent (POME) contains high organic compounds and nutrients suitable for microorganisms in anaerobic processes. The biological hydrogen production using raw POME and ozonated POME in thermophilic batch fermentation at varying POME concentration in the range of 5,000 to 35,000 mg COD L-1 was examined. Hydrogen production using the ozonated POME achieved the maximum yield of 77.1 mL g-1COD at 35,000 mg COD L-1, which higher than that from the raw POME by 20%. Meanwhile the hydrogen production rate of 10.8 mL h-1 was observed at the ozonated POME concentration of 25,000 mg COD L-1. Greater COD removal in the ozonated POME by 25% compared to that in the raw POME. The main acetic and butyric acids were accumulated in the raw POME fermentation which is lower than the ozonated POME fermentation. This work demonstrated ozonation of POME significant improved performance of the thermophilic biohydrogen production.

Thermophilic biohydrogen production: how far are we?

Apart from being applied as an energy carrier, hydrogen is in increasing demand as a commodity. Currently, the majority of hydrogen (H2) is produced from fossil fuels, but from an environmental perspective, sustainable H2 production should be considered. One of the possible ways of hydrogen production is through fermentation, in particular, at elevated temperature, i.e. thermophilic biohydrogen production. This short review recapitulates the current status in thermophilic biohydrogen production through fermentation of commercially viable substrates produced from readily available renewable resources, such as agricultural residues. The route to commercially viable biohydrogen production is a multidisciplinary enterprise. Microbiological studies have pointed out certain desirable physiological characteristics in H2-producing microorganisms. More process-oriented research has identified best applicable reactor types and cultivation conditions. Techno-economic and life cycle analyses have identified key process bottlenecks with respect to economic feasibility and its environmental impact. The review has further identified current limitations and gaps in the knowledge, and also deliberates directions for future research and development of thermophilic biohydrogen production.

Thermophilic biohydrogen production from the enzymatic hydrolysate of cellulose fraction of sweet sorghum bagasse by Thermoanaerobacterium thermosaccharolyticum KKU19: Optimization of media composition

The composition of media for thermophilic biohydrogen production from the enzymatic hydrolysate of cellulose fraction of sweet sorghum bagasse by Thermoanaerobacterium thermosaccharolyticum KKU19 were optimized in order to maximize the hydrogen production potential (Ps). Results from Plackett-Burman design indicated that FeSO4, CaCl2, NaHCO3, and MgCl2 had a significantly effect (P ≤ 0.05) on Ps. The optimum media composition obtained from the response surface methodology (RSM) with central composite design (CCD), using the hydrolysate at a total sugar concentration of 8.98 g/L, were (all in mg/L): FeSO4, 1454.65; MgCl2, 511.36; CaCl2, 278.62; and NaHCO3, 2186.41 in which the Ps of 2397 mL H2/L were obtained. Verification experiment using the optimum media composition in a continuous stirred tank reactor indicated a highly reproducible result in which the Ps of 2608 mL H2/L was achieved at a hydraulic retention time of 32 h. The results demonstrated that the media composition obtained from the batch experiment using RSM with CCD can be practically applied to continuously produce hydrogen from the hydrolysate with the least error.

Thermophilic bio-hydrogen production from food industry waste in suspended- and attached-cell reactors: preliminary screening in 0.12-L bioreactors and scale-up to a 19-L pilot reactor

Thermophilic bio-hydrogen production from food industry waste in suspended- and attached-cell reactors: preliminary screening in 0.12-L bioreactors and scale-up to a 19-L pilot reactor

Media optimization for biohydrogen production from waste glycerol by anaerobic thermophilic mixed cultures

Media compositions affecting thermophilic biohydrogen production from waste glycerol were optimized using response surface methodology (RSM) with central composite design (CCD). Investigated parameters used were waste glycerol concentration, urea concentration, the amount of Endo-nutrient addition and disodium hydrogen phosphate (Na2HPO4) concentration. Waste glycerol concentration and the amount of Endo-nutrient addition had a significant individual effect on the cumulative hydrogen production (HP) (p ≤ 0.05). The interactive effect on HP was found between waste glycerol and urea concentration as well as waste glycerol concentration and the amount of Endo-nutrient addition (p ≤ 0.05). The optimal media compositions were 20.33 g/L of waste glycerol, 0.16 g/L of urea, 3.97 g/L of Na2HPO4 and 0.20 mL/L of the amount of Endo-nutrient addition which gave the maximum HP of 1470.19 mL H2/L. The difference between observed HP (1502.84 mL H2/L) and predicted HP was 2.22%. The metabolic products from the fermentation process were 1,3-propanediol (1,3-PD), ethanol, acetic, formic, lactic, butyric, and propionic acids. Results from polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis indicated that the hydrogen producers present in the fermentation broth was Thermoanaerobacterium sp.

Decentralized thermophilic biohydrogen: A more efficient and cost-effective process

Nonfood lignocellulosic biomass is an ideal substrate for biohydrogen production. By avoiding pretreatment steps (acid, alkali, or enzymatic), there is potential to make the process economical. Utilization of regional untreated lignocellulosic biomass by cellulolytic and fermentative thermophiles in a consolidated mode using a single reactor is one of the ways to achieve economical and sustainable biohydrogen production. Employing these potential microorganisms along with decentralized biohydrogen energy production will lead us towards regional and national independence having a positive influence on the bioenergy sector.

Engineered heat treated methanogenic granules: A promising biotechnological approach for extreme thermophilic biohydrogen production

In the present study, two granular systems were compared in terms of hydrogen production rate, stability and bacterial diversity under extreme thermophilic conditions (70 degrees C). Two EGSB reactors were individually inoculated with heat treated methanogenic granules (HTG) and HTG amended with enrichment culture with high capacity of hydrogen production (engineered heat treated methanogenic granules - EHTG), respectively. The reactor inoculated with EHTG (R(EHTG)) attained a maximum production rate of 2.7l H(2)l(-1)day(-1) in steady state. In comparison, the R(HTG) containing the HTG granules was very unstable, with low hydrogen productions and only two peaks of hydrogen (0.8 and 1.5l H(2)l(-1)day(-1)). The presence of active hydrogen producers in the R(EHTG) system during the reactor start-up resulted in the development of an efficient H(2)-producing bacterial community. The results showed that "engineered inocula" where known hydrogen producers are co-inoculated with HTG is an efficient way to start up biohydrogen-producing reactors.

Extreme thermophilic biohydrogen production from wheat straw hydrolysate using mixed culture fermentation: Effect of reactor configuration

Hydrogen production from hemicellulose-rich wheat straw hydrolysate was investigated in continuously-stirred tank reactor (CSTR), up-flow anaerobic sludge bed (UASB) reactor, and anaerobic filter (AF) reactor. The CSTR was operated at an hydraulic retention time (HRT) of 3 days, and the UASB and AF reactors were operated at 1 day HRT, using mixed extreme thermophiles at 70 °C. The highest hydrogen production yield of 212.0 ± 6.6 mL-H 2/g-sugars, corresponding to a hydrogen production rate of 821.4 ± 25.5 mL-H 2/d L was achieved with the UASB reactor. Lowering the HRT to 2.5 days caused cell mass washout in the CSTR, while the UASB and AF reactors gave fluctuating and reducing hydrogen production at a 0.5-day HRT. The original rate and yield were recovered when the HRT was increased back to 1 day. These results demonstrate that reactor configuration is an important factor for enhancing and stabilizing H 2 production.

The effect of the surface charge of hydrogel supports on thermophilic biohydrogen production

The effect of the surface charge of different immobilizing hydrogels on biohydrogen production in batch cultures was investigated using a novel isolate associated to the genus Thermoanaerobacterium. Two crosslinked polysaccharide-based hydrogels and two acrylic hydrogels were tested as polymeric carriers for cell adsorption. Immobilization improved both substrate conversion and hydrogen cumulative production compared to the suspended culture, and a yield of 1.9mol H2/mol glucose was observed after 24h for alginate-supported cultures. Cationic carriers dramatically increased cell immobilization, leading to markedly faster kinetics of substrate degradation and hydrogen production in batch operation, with a peak of 3.6mol H2/mol glucose for the acrylic hydrogel HM92. Accumulation of gaseous and acidic metabolites inhibited further H2 production, shifting the carbon flow to reduced end-products and biomass synthesis. Preliminary tests showed that all the tested hydrogels had good durability and allowed hydrogen production on repeated batch runs.