Thermophilic Biohydrogen Production Research Articles

Effect of pH, temperature and agitation on thermophilic biohydrogen production using immobilized cells on carbon composites (GAC-NiFe3O4)

Carbon composites-immobilized cell was utilized to enhance biohydrogen production. The initial pH, temperature and agitation effect was studied using the one-factor-at-a-time (OFAT) method. The optimal initial pH obtained was at pH 6.0 with hydrogen yield (HY) of 2.66 ± 0.09 mol H2/mol sugar, correlating with Gompertz constant of Hm = 974.99 mL, Rm = 17.90 mL/h and λ = 1.70 h. At 60 °C, the highest HY was obtained at 2.75 ± 0.11 mol H2/mol sugar. These corresponded to the Gompertz constant of Hm = 934.58 mL, Rm = 18.78 mL/h and λ = 1.89 h. The optimal agitation obtained was at 120 rpm, attaining the highest HY of 3.44 ± 0.54 mol H2/mol sugar, corresponding to the Gompertz constant of Hm = 1054.86 mL, Rm = 24.37 mL/h and λ = 3.90 h. The rRNA sequencing result revealed that the predominant species in the study was Thermoanaerobacterium. This study provides critical insight into process control conditions on biohydrogen production.

Thermophilic biohydrogen production from optimized enzymatic pretreatment of palm oil mill effluent via box-behnken design

The demand for energy is increasing continuously due to the vast developments in many ways of life. Palm oil mill effluent (POME) seems to be a good carbon feedstock for hydrogen generation in fermentation processes. A biological pretreatment was applied to degrade the lignocellulose biomass in the anaerobic digestion process and improve the bioenergy production yield; one of the techniques is to use enzymes. In this study, enzymatic pretreatment was applied to POME to determine the optimum process parameters for producing reducing sugars (RS) to be used as a substrate in biohydrogen production. The Box-Behnken design (BBD) was used to construct an experiment to optimize the pretreatment variables, such as reaction time (h), enzyme concentration (% w/v), and pH. The optimum experimental conditions were found to be 12 hr of reaction time, an enzyme concentration of 3.76% w/v, and pH 5. The result showed that POME treated with the optimal enzymatic pretreatment increased the RS content by 182%. Next, thermophilic biohydrogen production using a pretreated substrate was carried out at a temperature of 55 °C, mixing speed of 150 rpm, Chemical Oxygen Demand (COD) concentration of 29,100 mg/L, seed content of 18.2%, and initial pH 7.14. The biohydrogen production potential (Hmax) was significantly increased by 145% (177 mL H2/g reducing sugar) by using enzymatically pretreated POME as a substrate. This result indicated that the recovery of RS from recalcitrant POME via enzymatic pretreatment could enhance biohydrogen production. Hence, it is a useful proposal for further application in bioenergy conversion from organic waste.

Biohydrogen production with utilisation of magnetite nanoparticles embedded in granular activated carbon from coconut shell

This study aims to utilize magnetite nanoparticles (MNP) embedded in granular activated carbon (GAC) originating from coconut shells as microbial support carriers in thermophilic biohydrogen production. MNP can facilitate intracellular electron transportation while providing essential nutrition for microbial growth. Response Surface Methodology (RSM) with a Central Composite Design was used to investigate the simultaneous effect of three variables; Ni:Fe (0.25–0.80), MNP:GAC (0.01–0.03) and type of GAC (GAC-O or GAC-C) on the hydrogen productivity rate (HPR). Biohydrogen content in the biogas to range from 22.25 to 64.71%. The quadratic model was well fitted (R-squared>0.80) with a confidence level higher than 90%. The optimum magnetite GAC was GAC-O as the preferred GAC at Ni:Fe (0.53) and MNP:GAC (0.02), with HPR of 20.33 ± 0.32 ml H2/L.h. Magnetite GAC exhibited a better biohydrogen productivity rate by 63.99% compared to non-magnetite GAC. The developed magnetite GAC shown a high potential to improve biohydrogen production.

Thermophilic biohydrogen production strategy using agro industrial wastes: Current update, challenges, and sustainable solutions

Continuously increasing wastes management issues and the high demand of fuels to fulfill the current societal requirements is not satisfactory. In addition, severe environmental pollution caused by generated wastes and the massive consumption of fossil fuels are the main causes of global warming. In this scenario, production of hydrogen from organic wastes is a potential and one of the most feasible alternatives to resolve these issues. However, sensitivity of H2 production at higher temperature and lack of potential substrates are the main issues which are strongly associated with such kinds of biofuels. Therefore, the present review is targeted towards the evaluation and enhancement of thermophilic biohydrogen production using organic, cellulosic wastes as promising bioresources. This review discusses about the current status, development in the area of thermophilic biohydrogen production wherein organic wastes as key substrate are being employed. The combinations of suitable organic and cellulose rich substrates, thermo-tolerant microbes, high enzymes stability may support to enhance the biohydrogen production, significantly. Further, various factors which may significantly contribute to enhance biohydrogen production have been discussed thoroughly in reference to the thermophilic biohydrogen production technology. Additionally, existing obstacles such as unfavorable thermophilic biohydrogen pathways, inefficiency of thermophilic microbiomes, genetic modifications, enzymes stability have been discussed in context to the possible limitations of thermophilic biohydrogen production strategy. Structural and functional microbiome analysis, fermentation pathway modifications via genetic engineering and the application of nanotechnology to enhance the thermophilic biohydrogen production have been discussed as the future prospective.

Mesophilic and thermophilic biohydrogen production using cassava starch wastewater in a CSTR

The objective of this work is to compare and evaluate the production of biohydrogen (bio-H2) from cassava starch wastewater at mesophilic and thermophilic conditions and to elucidate the metabolic routes involved. This system consisted of a continuous stirred-tank reactor for hydrogen production under the influent organic loading rate (OLRs) of 2.08, 5.05, 12.04, 23.34, and 30.87 kg COD/(m3•d) for mesophilic temperature and 2.29, 4.47, 12.52, 22.09 and 28.86 kg COD/(m3•d) for thermophilic temperature with Hydraulic Retention Time of 24, 16, 12 and 8 hours and pH maintained 5 to 6. The steady state of hydrogen production was 3131 ml/L•d obtained at the OLR of 23.34 kg COD/(m3•d) with the COD removal of 85%, and the hydrogen production of 2007 ml/L.d with a COD removal of % was obtained at the OLR of 28.86 kg COD/(m3•d). The maximum of 85% of the cassava starch wastewater was converted to hydrogen at the OLR of 23.34 kg COD/(m3•d) at mesophilic conditions with HRT of 8 h and hence the mesophilic condition favoured the hydrogen production using cassava starch wastewater.

Zeolite addition to improve biohydrogen production from dark fermentation of C5/C6-sugars and Sargassum sp. biomass

Thermophilic biohydrogen production by dark fermentation from a mixture (1:1) of C5 (arabinose) and C6 (glucose) sugars, present in lignocellulosic hydrolysates, and from Sargassum sp. biomass, is studied in this work in batch assays and also in a continuous reactor experiment. Pursuing the interest of studying interactions between inorganic materials (adsorbents, conductive and others) and anaerobic bacteria, the biological processes were amended with variable amounts of a zeolite type-13X in the range of zeolite/inoculum (in VS) ratios (Z/I) of 0.065–0.26 g g−1. In the batch assays, the presence of the zeolite was beneficial to increase the hydrogen titer by 15–21% with C5 and C6-sugars as compared to the control, and an increase of 27% was observed in the batch fermentation of Sargassum sp. Hydrogen yields also increased by 10–26% with sugars in the presence of the zeolite. The rate of hydrogen production increased linearly with the Z/I ratios in the experiments with C5 and C6-sugars. In the batch assay with Sargassum sp., there was an optimum value of Z/I of 0.13 g g−1 where the H2 production rate observed was the highest, although all values were in a narrow range between 3.21 and 4.19 mmol L−1 day−1. The positive effect of the zeolite was also observed in a continuous high-rate reactor fed with C5 and C6-sugars. The increase of the organic loading rate (OLR) from 8.8 to 17.6 kg m−3 day−1 of COD led to lower hydrogen production rates but, upon zeolite addition (0.26 g g−1 VS inoculum), the hydrogen production increased significantly from 143 to 413 mL L−1 day−1. Interestingly, the presence of zeolite in the continuous operation had a remarkable impact in the microbial community and in the profile of fermentation products. The effect of zeolite could be related to several properties, including the porous structure and the associated surface area available for bacterial adhesion, potential release of trace elements, ion-exchanger capacity or ability to adsorb different compounds (i.e. protons). The observations opens novel perspectives and will stimulate further research not only in biohydrogen production, but broadly in the field of interactions between bacteria and inorganic materials.

Dark fermentation of palm oil mill effluent by Caldicellulosiruptor saccharolyticus immobilized on activated carbon for thermophilic biohydrogen production

The first attempts were made to investigate the performance of extreme thermophile Caldicellulosiruptor saccharolyticus immobilized on granular activated carbon (GAC) utilizing palm oil mill effluent for hydrogen production. It found that the strain fermented well in raw palm oil mill effluent (POME) wastewater; bring to highest hydrogen productivity rates (HPR) of 20.8 mL H 2 /L h, at 12 g/L total carbohydrates (TC) in sterile condition; and 29.8 mL H 2 /L h HPR at 9 g/L TC, in contrast, in non-sterile condition. Meanwhile, HPR of 38.8 mL H 2 /L h, with a yield of 3.0 mol H 2 /mol sugar found as highest at 10 g/L glucose, indicates this bacteria can perform well in a robust environment. Immobilization of C. saccharolyticus on activated carbon by supplementing POME-enriched nutrient leads to the highest yields of 2.6 mol H 2 /mol of sugar, at 10% POME concentration. However, the results with other POME concentrations are not significantly different, indicating the new attempt of immobilized C. saccharolyticus on GAC seems promising to achieve consistent HPR at extreme thermophilic conditions. • Performances Caldicellulosiruptor saccharolyticus on activated carbon were studied. • Biohydrogen were produced using palm oil mill effluent as carbon source. • Effect of wide range sugar concentration were evaluated in H 2 production.

Comparison of mesophilic and thermophilic biohydrogen production amended by nickel-doped magnetic carbon

The use of carbon composites and trace elements in biogas production has been demonstrated as an efficient approach. However, the relationship between carbon materials and the microbial community needs further clarification. In this study, a novel nickel-doped magnetic carbon material was produced to compare its role in biohydrogen (bioH2) production under mesophilic (37 °C) and thermophilic (55 °C) conditions. Material characterization showed that NiFe2O4 and Ni(OH)2 were well doped into the activated carbon without obviously reducing its specific surface area. A moderate amount (200–600 mg/L) of magnetic carbon boosted bioH2 production, while excess magnetic carbon inhibited bioH2 evolution. The highest H2 yields of 260 and 192 mL/g glucose were found at 600 mg/L (37 °C) and 800 mg/L magnetic carbon (55 °C), which were 46.9% and 60.0% higher than the control yields, respectively. The microbial community revealed that such magnetic carbon significantly increased the abundance of Clostridium sensu stricto 1 (57.91%) in the mesophilic process, and Clostridium sensu stricto 7 (24.29%), 8 (7.39%) and 10 (24.85%) were the dominant bacteria in thermophilic fermentation. The results also showed that the production of clean energy with a higher yield of H2 and a low cost of production was achieved at 37 °C compared with those at 55 °C.

Comparative evaluation of the mesophilic and thermophilic biohydrogen production at optimized conditions using tequila vinasses as substrate

The objective of this work was to comparatively evaluate the production of biohydrogen (bio-H2) from tequila vinasses at optimized mesophilic and thermophilic conditions and to elucidate the main metabolic routes involved. Optimal temperatures of 35 °C and 55 °C, and pH of 5.5 maximized the bio-H2 production rates, 25.5 ± 0.01 NmL h−1 and 169.9 ± 8.9 NmL h−1 in the mesophilic and thermophilic regimens, respectively. During the operation of anaerobic sequencing batch reactors, the thermophilic process allowed a volumetric bio-H2 production rate of 519 ± 13 NmL-H2 L−1 d−1 equivalent to 750 ± 19 NmL-H2 Lvinasse−1, while the mesophilic one 448 ± 23 NmL-H2 L−1 d−1 and 647 ± 33 NmL-H2 Lvinasse−1, respectively. Furthermore, the gas produced under thermophilic conditions showed high hydrogen content (86.5%). Finally, formate degradation and glucose fermentation to acetic and butyric acids were the main metabolic routes involved in bio-H2 production under thermophilic conditions, while at mesophilic conditions, the lactate and formate degradation pathways governed.

Thermophilic biohydrogen production from sugarcane molasses under low pH: Metabolic and microbial aspects

By-products from sugarcane mills have a considerable energy potential, and therefore have been studied aiming to generate biogas emphasising biohydrogen (bioH2). Sugarcane molasses, a byproduct from sugar production, are rich in carbohydrates, thus easily biodegraded by anaerobic microorganisms. This study evaluated the production of bioH2 in unfavorable pH (3.80) using molasses as a feedstock in an anaerobic structured bed reactor (AnSTBR-A) under thermophilic conditions (55 °C). The AnSTBR-A operated with an organic loading rate (OLR) of 60 g L−1 d−1 was able to produce bioH2 under long-term operation (392 days). The hydrogen yield (HY) was 1.18 mol H2 mol total carbohydrates−1. The results highlighted HY variation concomitant with metabolite concentrations. The main role to bioH2 production in AnSTBR-A was acetate + lactate → butyric + bioH2, with a predominance of the organism belonging to the Thermoanaerobacterium genus.

Thermophilic biohydrogen production from palm oil mill effluent: Effect of immobilized cells on granular activated carbon in fluidized bed reactor

In this study, the performance of immobilized cells on granular activated carbon (GAC) for thermophilic biohydrogen production is determined using POME as a fermentation substrate. The immobilized cells are formed at different pH medium using sugar composition characterized in the POME. The pH 6 revealed the optimum pH used for biofilm development with HPR of 2.8mmol H2/Lh. The effect of sugar utilization by the immobilized cells on GAC are determined at different sugar concentration using the Monod model prior validated the performance of the cells in the fluidized bed reactor (FBR). From the model, 0.316±0.013h−1 of maximum specific growth rate was obtained at 20g/L sugar used and was keep increasing to the maximum of 30g/L of sugar used with HPR 2.6–2.8mmol H2/Lh. Lastly, the POME-enriched nutrients are used as the carbon source in the fluidized bed reactor (FBR). The highest HPR obtained was at HRT 12h, (5.2mmol H2/Lh) and HY of 1.24mol H2/mol sugar. The screening of the microbial population by DGGE revealed that the Thermoanaerobacterium thermosaccharolyticum sp. was dominant for all the HRTs, thereby indicating that this bacterium is resilient towards environmental disturbances.

Two-stage thermophilic bio-hydrogen and methane production from lime-pretreated oil palm trunk by simultaneous saccharification and fermentation

A simultaneous saccharification and fermentation (SSF) process was applied for thermophilic bio-hydrogen production from lime-pretreated oil palm trunk (OPT) by Thermoanaerobacterium thermosaccharolyticum KKU19. The SSF hydrogen fermentation conditions were optimized to maximize hydrogen yield (HY). Based on Plackett-Burman design, substrate loading and initial pH had significant effects on HY. The substrate loading and initial pH were further optimized using response surface methodology with a central composite design. The optimum conditions were a substrate loading, enzyme loading, inoculum concentration, initial pH and temperature of 4.6%, 10 filter paper unit (FPU)/g-OPT, 10% (v/v), 6.3 and 50 °C, respectively, which yielded the highest HY of 60.22 mL H2/g-OPT. Structural analysis showed that lime pretreatment and SSF decreased the crystallinity of OPT. Methane production was carried out following the hydrogen production to improve the energy yield from OPT. The results showed that methane production increased total energy yield from 0.65 to 11.79 kJ/g-OPT under the optimal conditions.

Enhanced thermophilic bioenergy production from food waste by a two-stage fermentation process

PurposeThe objective of research was emphasized on the optimal conditions (initial pH and C/N ratio) for enhancing bioenergy from food waste by a two-stage fermentation process.MethodsBioenergy production from food waste was operated by mixed culture under thermophilic temperature in batch reactor. Thermophilic biohydrogen production was optimized in terms of initial pH (5.0–9.0) and then was optimized in terms of C/N ratio (10–50) in the first stage. After that, thermophilic biomethane production was optimized in terms of initial pH (6.0–10.0) in the second stage.ResultsThe results revealed that the thermophilic biohydrogen production from food waste at an initial pH 7.0 presented the maximum hydrogen yield of 176.10 mL H2/g COD. At this optimal initial pH, the maximum hydrogen yield of 214.88 mL H2/g COD was achieved at C/N ratio 30. Subsequently, the effluent from the first stage of thermophilic biohydrogen production from food waste under the optimal initial pH of 7.0 and the optimal C/N ratio of 30 was used as a substrate in the second stage of thermophilic biomethane production. Thermophilic biomethane production from hydrogen fermentation effluent provided the maximum methane yield of 310.77 mL CH4/g COD at initial pH 7.0. At these optimal conditions, COD removal was achieved at 70–90%.ConclusionTherefore, a two-stage thermophilic fermentation process could effectively enhance biohydrogen and biomethane production, including reduction of organic waste at the same time.

Two-stage thermophilic bio-hydrogen and methane production from oil palm trunk hydrolysate using Thermoanaerobacterium thermosaccharolyticum KKU19

The two-stage process for thermophilic bio-hydrogen production followed by methane production was examined on a hydrolysate obtained from oil palm trunk (OPT). The optimum conditions for lime pretreatment and enzymatic hydrolysis of OPT was a lime loading of 0.2 g Ca(OH)2/g-OPT, pretreatment time of 60 min, temperature of 121 °C and enzyme loading of 35 filter paper units/g-OPT. A maximum total reducing sugar yield of 473 mg/g-OPT was obtained, which was 2.7-fold higher than that of untreated OPT. The OPT hydrolysate was used as a substrate for bio-hydrogen production by Thermoanaerobacterium thermosaccharolyticum KKU19 in the first stage. The maximum hydrogen production potential of 2179 mL H2/Lsubstrate was obtained under the optimum conditions of 16.5 g/L initial substrate concentration, initial pH of 6.7 and 54.5 °C, respectively. Acidic effluent was used to produce methane in the second stage in which the methane yield of 272.4 mL/g-chemical oxygen demand (COD) was achieved. The two-stage hydrogen and methane production resulted in energy yield of 10.6 kJ/g-CODadded with 83% COD removal.

Pretreatment conditions of palm oil mill effluent (POME) for thermophilic biohydrogen production by mixed culture

The availability of fermentable sugars in POME is one of the critical factors that determine the fermentative biohydrogen production yield. This study was carried out to determine the pretreatment conditions viz., temperature, hydrolysis time and acid concentration that can yield the highest monomeric sugars, to be utilized for production of biohydrogen from POME by mixed culture dark fermentation. Two different acids were used, nitric acid and phosphoric acid in the pretreatment of POME. Batch fermentation was performed to determine the potential of pretreated POME as a substrate for the production of biohydrogen under the tested pretreatment conditions. Higher hydrogen yield was successfully achieved using pretreated POME as compared to raw POME by mixed culture. Maximum hydrogen production was 0.181 (mmol/L/h), which corresponded to the yield of 1.24 mol H2/mol glucose achieved at 0.8% (w/v) phosphoric acid with initial total reducing sugar concentration of 18.47 g/L. Hence, the results implied that POME pretreated with 0.8% (w/v) phosphoric acid is a potential substrate for efficient biohydrogen fermentation yield that is 97% higher than untreated POME. While POME pretreated with 1% (w/v) of nitric acid showed 65% improvement in biohydrogen yield as compared to untreated POME. Therefore, the results implied that both pretreatment methods of POME showed significant increase in the biohydrogen production.

Enhancement in lipid content of Chlorella sp. MJ 11/11 from the spent medium of thermophilic biohydrogen production process

The present study investigates the effect of spent media of acetogenic dark fermentation for mixotrophic algal cultivation for biodiesel production. Mixotrophic growth conditions were optimized in culture flask (250mL) using Chlorella sp. MJ 11/11. Maximum lipid accumulation (58% w/w) was observed under light intensity, pH, nitrate and phosphate concentration of 100μmolm−2s−1, 7, 2.7mM and 1.8mM, respectively. Air lift (1.4L) and flat panel (1.4L) reactors were considered for algal cultivation. Air lift showed significant improvement in biomass and lipid production as compared to flat panel reactor. The results could help in development of sustainable technology involving acetogenic hydrogen production integrated with sequential mitigation of spent media by algal cultivation for improved energy recovery.

Particle size variations of activated carbon on biofilm formation in thermophilic biohydrogen production from palm oil mill effluent

In this study, we examined the formation of thermophilic microbial biofilm by self-attachment on microbial carrier of granular activated carbon (GAC) in five different micro-pore volumes 0.31, 0.41, 0.44, 0.48, and 0.50cm3/g. It was found that the highest hydrogen production rate of 100.8±3.7mmol H2/l.d and yield of 1.01±0.07mol H2/mol sugar were obtained at 0.44cm3/g volume size of GAC. The cellulolytic activity of attached-biofilm was further investigated using POME as a feedstock. The results showed that in all diluted POME substrate, the total sugar consumed by the microbes was found higher than that the amount of soluble monomeric sugar present in the POME medium. It is believe that the microbial biofilm was able to hydrolyse polymeric sugar of cellulosic fibre in the POME by performing enzymatic hydrolysis into simple monomeric sugar. The isolated biofilm bacteria that subjected to 16S rRNA gene analysis presented 99% high homology to the species of Thermoanaerobacterium thermosaccharolyticum which were guaranteed to perform a cellulosic degradation activity.

Biofilm formation on granular activated carbon in xylose and glucose mixture for thermophilic biohydrogen production

Granular activated carbon (GAC) was used as a support carrier to develop biofilm of Thermophilic biohydrogen producer in an immobilized system of dark fermentation. The optimum ratio of the sludge to GAC loading was investigated in batch fermentation using glucose and xylose mixture as a carbon source. It was found that the highest hydrogen yield of 1.77 mol H2/mol substrate consumed and hydrogen production rate (HPR) of 2.0 mmol H2/l.h, were achieved at a sludge-GAC ratio of 1:2. On the other hand, the experiments with suspended culture as a control gave poor performance of hydrogen yield (0.86 mol H2/mol of substrate consumed) and HPR (0.5 mmol H2/l.h). The sludge-GAC biofilm was further developed in a sequencing batch feeding mode through controlled acclimatization condition. Stable hydrogen production was achieved after day 40th with consistent HPR of 2.4 mmol H2/l.h and yield of 1.17 mol H2/mol substrate consumed with 44.2% of hydrogen. Acetic and butyric acids dominate volatile fatty acids (TVFAs) as a major by-product while ethanol being the only alcohol produced but in a minor amount. This work has proven the possible future of GAC attached biofilm sludge as promising attachment system to achieve consistent hydrogen production even at thermophilic conditions.

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