Photofermentative Biohydrogen Production Research Articles

Lignin removal, reducing sugar yield and photo-fermentative biohydrogen production capability of corn stover: Effects of different pretreatments

The effects of different pretreatment methods, including hydrothermal, acid, alkali, acid-heat and alkali-heat on lignin removal, reducing sugar (RS) yield and photo-fermentative biohydrogen production (PFHP) capability of corn stover (CS) were studied. NaOH-heat pretreatment was the most effective for lignin removal from CS, and the lignin removal rate reached 77%. All the studied pretreatment methods improved the total RS yield of CS, and the highest total RS yield (46.1 g/100 g raw material (RM)) was obtained from 2% NaOH-heat pretreated CS. 2% NaOH pretreatment realized the best PFHP of CS, which increased the hydrogen yield (HY), maximal hydrogen production rate (HPR) and highest hydrogen content (HC) by 31.9%, 50.9% and 20.1% respectively, and shortened hydrogen production lag time (HPLT) by 58.8% over that of untreated CS. However, NaOH-heat and 4% NaOH pretreatment weakened the PFHP capability of CS.

Optimisation of photo-fermentative biohydrogen production from corn stover through the synergetic effect of ultrafine grinding and SnO2 nanomaterials

The synergetic effect of ultrafine grinding coupled with the incorporation of an appropriate amount of nanomaterials (NMs) on biohydrogen (bioH2) production from corn stover (CS) was studied. The changes in the physicochemical and optical characteristics of CS pretreated with various ultrafine grinding times were comprehensively studied. High-quality SnO2 NMs with high defect concentrations (e.g., oxygen vacancies (OVs)) were successfully synthesised. The physio-optical structures of pretreated CS and synthesised NMs were analysed using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and diffuse reflectance spectroscopy. SEM measurements confirmed that the morphology of the CS changed with the increase in grinding time and the particle size was reduced to the submicron range with increased surface roughness. The biomass particle size changed considerably from micron to submicron with an increase in grinding time. The intensities of the diffracted peak 22° decreased and the full width at half maximum increased with the increase in grinding time, which confirmed the considerable modification of biomass crystalline structure. The SEM analysis revealed that the synthesised SnO2 NMs were spherical in nature with a uniform size distribution. XRD analysis confirmed that the synthesised NMs had a stable rutile structure without any secondary phases. Hydrogen production tests were performed by utilising a mixed consortium of photosynthetic bacteria HAU-M1 as the inoculum. Hydrogen production rates of 120, 123, and 145 mL/h were observed for samples pretreated with 2, 4, and 6 h of ultrafine grinding, respectively. Owing to the synergetic effect of ultrafine grinding and nanomaterial loading, the hydrogen production rate increased considerably to 143, 144, and 163 mL/h after 2, 4, and 6 h of ultrafine grinding and nanomaterial loadings of 200, 150, and 150 mg/L, respectively. The highest cumulative bioH2 production of 425 mL was recorded after ultrafine grinding for 6 h and nanomaterial loading of 150 mg/L, 49% higher than that achieved with the standard sample (285 mL). Furthermore, the synergetic effect reduced not only the lag time (from 36 to 24 h) but also the amount of SnO2 NMs loading required to achieve the highest hydrogen production rate (150 mg/L) as compared with the standard sample (200 mg/L). Our results highlight that an appropriate combination of pretreatments can present a potential roadmap to enhance bioH2 production from lignocellulosic biomass, which can be a prospective sustainable energy supply.

Enhancing photo-fermentation biohydrogen production by strengthening the beneficial metabolic products with catalysts

The aim of the present study is to evaluate the role of catalysts in enhancing the energy conversion efficiency and photo-fermentation biohydrogen yield from corn stalk (CS) by strengthening the beneficial metabolic products. The effects of catalysts on biohydrogen production, fermentation broth, energy conversion efficiency, and CS structure were studied. The maximum hydrogen yield (160.4 ± 2.7 mL/g CS) and highest energy conversion efficiency (11.90%) were achieved at a zeolite concentration of 0.2 g/g CS, which was 33.33% higher prior to catalyst addition. A 15.93% increase in hydrogen yield was obtained by adding 0.2 g/g CS of kieselguhr to the liquid culture. While no significant increase in hydrogen yield was found when activated carbon was added, it was found that zeolite can significantly increase the energy conversion efficiency and biohydrogen yield by controlling the metabolism of sugar to propionic during the photo-fermentation process. The interaction of enzymolysis and biohydrogen production significantly changed the microstructure of CS. It is of great significance to improve the utilization of CS and the performance of photo-fermentation biohydrogen production. Furthermore, it is conducive to the cleaner production and industrial promotion of biological hydrogen production.

Study of the interrelationship between nano-TiO2 addition and photo-fermentative bio-hydrogen production of corn straw

This study explored the interrelationship between nano-TiO2 addition and photo-fermentative hydrogen production (PFHP) of corn straw. The maximum cumulative hydrogen volume (CHV) was up to 688.8 mL under the optimal photo-fermentative process conditions with nano-TiO2 addition of 300 mg/L. Initial pH and interaction between substrate concentration and light intensity had highly significant effects on PFHP of corn straw with nano-TiO2 addition. With the improvement of CHV, nano-TiO2 addition decreased the optimal initial pH and substrate concentration for PFHP of corn straw. Moreover, nano-TiO2 addition promoted the metabolism of butyric acid and acetic acid by photosynthetic bacteria HAU-M1, and significantly reduced the total concentration of intermediate byproducts during hydrogen production to a low level of 1.6–2.5 g/L, thus making the CHV, maximum hydrogen production rate (HPR) and average hydrogen content (HC) increased by 32.6%, 27.9% and 8.3% respectively over the control without nano-TiO2 addition.

Tolerance of photo-fermentative biohydrogen production system amended with biochar and nanoscale zero-valent iron to acidic environment

Anaerobic fermentation system is easy to become acidic due to the generation of small molecular acids, which will affect the metabolism of bacteria. Therefore, it is necessary to improve the acid resistance of system. In this work, the tolerance of photo-fermentative biohydrogen production system amended with biochar, nanoscale zero-valent iron (nZVI) and biochar + nZVI to acidic environment was studied. Results showed that additives improved the stability and performance of the photo fermentation. The best increment of biohydrogen from 0 to 286.83 ± 2.77 mL was obtained by adding biochar and nZVI together at the original pH of 4.5. The additive reduced the oxidation–reduction potential and promoted the consumption of acetate and butyrate. At initial pH of 5, 6 and 7, the highest biohydrogen yield of 361.02 ± 10.11, 419.36 ± 10.70 and 382.67 ± 25.08 mL was obtained by adding nZVI, respectively, representing 42%–44.45% increase compared with the control group under the same conditions.

Photo-fermentative biohydrogen production from corncob treated by microwave irradiation

The complex structure of corncob is the bottleneck that restricts its efficient biohydrogen production. Hence, effective treatment is an important exploration to break this limitation. The effect of microwave irradiation (MI) on photo-fermentative biohydrogen production (PFHP) process was evaluated in this paper. Diverse conditions (irradiation time, microwave power, and surfactant addition) were applied. Comparisons of cumulative hydrogen yield (CHY), microstructure, liquid products, and substrate conversion efficiency (Sconv) were conducted. Results showed that the highest CHY of 27.34 ± 1.13 mL/g TS was achieved when the corncob was treated by MI assisted with surfactant addition. Optimal treatment conditions (5.51 min irradiation time, 772.03 W microwave power, and 0.08 g/L rhamnolipids addition) were obtained. MI assisted with surfactant addition helped with the structure destroys and content degradation, displaying a great improves on PFHP. Lower ethanol content and higher butyric acid content were obtained. An 80.94% increase in CHY and Sconv of 90.44% were obtained than untreated corncob.

Role of surfactant in affecting photo-fermentative bio-hydrogen production performance from corncob

Surfactant addition can cause a significant change in the interface state of the solution system, which is helpful to avoid agglomeration and sedimentation of solid state, and improve the mass transfer capacity. Hence, the performance of high-solid photo-fermentative bio-hydrogen production system with bio-surfactant addition was evaluated in this work. Corncob was selected as raw material, and cumulative hydrogen yield (CHY) was taken as reference. The effect of Rhamnolipids (RLs) and Tea Saponin (TSn) addition on hydrogen yield capacity was investigated. The results showed that CHY was effectively increased by the addition of RLs and TSn, the highest CHY of 356.42 ± 16.5 mL and 265.38 ± 7.5 mL appeared when the concentrations of surfactant addition were 0.08 g/L RLs and 1.5 g/L TSn, which were 67.85% and 24.97% higher than control group, respectively. The maximum energy conversion efficiency reached 5.47% and 4.08% with an increase of 67.8% and 25.2%.

Recycling of shrub landscaping waste: Exploration of bio-hydrogen production potential and optimization of photo-fermentation bio-hydrogen production process

Shrub landscaping waste, derived from afforestation of city, has increased annually, making it a promising feedstock for energy production. In this work, the photo-fermentation bio-hydrogen production potential from shrub landscaping waste was evaluated. Eight kinds of shrub landscaping wastes (Photinia fraseri, Buxus megistophylla, Buxus sinica, Pittosporum tobira, Sabina Chinensis, Berberis thunbergii, Ligustrum vicaryi and Ligustrum quihoui) were selected as substrate and the photo-fermentation bio-hydrogen production process of which was optimized. Buxus megistophylla was found to be the most suitable substrate for photo-fermentation bio-hydrogen production. Moreover, the initial pH value, temperature and substrate concentration had significant influence on photo-fermentation bio-hydrogen production. The maximum cumulated hydrogen yield of Buxus megistophylla was 73.82 ± 0.06 mL/g TS under the optimal conditions of light intensity of 3000 Lux, substrate mass concentration of 21.49 g/L, temperature of 29.78 °C, inoculant amount of 25% and initial pH value of 6.78.

Hydrogen production by sequential dark and photofermentation using wet biomass hydrolysate of Spirulina platensis: Response surface methodological approach

Microalgae and cyanobacteria can be used as a potential biomass to produce hydrogen from stored glycogen and starch through fermentation and photofermentation. In this study, the potential of algal biomass i.e. Spirulina platensis hydrolysate as a substrate for sequential fermentative (I-stage) and photo-fermentative (II-stage) biohydrogen production was evaluated. Response Surface Methodology (RSM) was employed to find the optimum photofermentation conditions. From the preliminary optimization experiments, it was found that the significantly affecting factors for H2 production were pH, dilution fold (D.F.) of fermentate and Fe(II) sulfate concentration during photofermentation (second stage). In the present study, 1% (w/v) Spirulina platensis hydrolyzate produced 23.06 ± 3.63 mmol of H2 with yield of 1.92 ± 0.20 mmol H2/g COD reduced. In the second stage experiment 1510 ± 35 mL/l hydrogen was produced using inoculum volume-20.0% (v/v) and inoculum age-48 h of co-culture of Rhodobacter sphaeroides NMBL-01 and Bacillus firmus NMBL-03 under conditions pH-5.95, D.F. of dark fermentate-20.30 folds, Fe(II) sulfate concentration-0.412 μM, temperature-32±2 °C and light intensity-2.5 klux.

A review on biohydrogen production through photo-fermentation of lignocellulosic biomass

Photo-fermentation biohydrogen production is an eye-catching and environmentally friendly route that can be excellently performed at ambient conditions. Nevertheless, light conversion efficacy and photo-fermentation hydrogen production performance are still low, and hence, numerous approaches are explored to enhance biohydrogen production. This review is intended at describing comprehensive characteristics and general mechanism of photo-fermentation biohydrogen production and highlights the advantages of this approach over other methods. Moreover, various pretreatment procedures of potential lignocellulosic biomass feedstocks for enhanced photo-fermentation biohydrogen production including physical, chemical, physical-chemical, and biological methods were elaborated thoroughly. Several crucial factors affecting photo-fermentation biohydrogen production such as the impact of pH, mixing, stirring, and lighting conditions, substrate concentration, different pretreatment conditions, and diverse fermentation modes were also discussed comprehensively. This aims to emphasize the recent advances in this field for further enhancement of biohydrogen production via photo-fermentation of lignocellulosic biomass. Additionally, the major challenge and prospects are also included to uncover the unexplored criteria of an effective and greener photo-fermentation biohydrogen production.

Enhanced buffer capacity of fermentation broth and biohydrogen production from corn stalk with Na2HPO4/NaH2PO4

The remarkable buffer capacity of buffer solution can significantly improve the biohydrogen production yield and energy conversion efficiency. In the present study, the effect of buffer solution Na2HPO4/NaH2PO4 on buffer capacity of fermentation broth and photo-fermentation biohydrogen production (PFHP) was studied. Gas characteristics, fermentation broth properties, and kinetic parameters in PFHP were investigated. With the increase in pH values (5–7) of buffer solution Na2HPO4/NaH2PO4, firstly hydrogen yield increased and then decreased. Maximum energy conversion efficiency 9.84%, hydrogen yield 132.69 mL/g corn stalk, and hydrogen content 53.88% were achieved at pH value of 6. The results of one-way ANOVA showed that pH values of fermentation broth and cumulative hydrogen production were strongly affected by pH values of buffer solution. Buffer solution Na2HPO4/NaH2PO4 retarded the decrease of pH value of photo-fermentation broth, and significantly improved the PFHP.

Investigation of the interaction between lighting and mixing applied during the photo-fermentation biohydrogen production process from agricultural waste

To better clarify the effect of lighting and mixing on the hydrogen production from agricultural waste, experiments under diverse constant and dynamic light intensities and mixing speeds were conducted. Cumulative hydrogen yield, hydrogen production rate, OD660, pH, reducing sugar concentration were monitored. Results showed that mixing had positive effects on high substrate concentration. The interaction between lighting and mixing was drawn. Higher light intensity (7000 Lux) was suitable for hydrogen production under mixing. Higher light intensity with higher mixing speed (150 RPM) showed the highest cumulative hydrogen yield of 78.1 mL/g TS. Different periods of hydrogen production process required distinct lighting and mixing. Combined with Gompertz model, dynamic lighting and mixing strategies were discussed. Dynamic light intensity (4000-7000-4000 Lux) accompanied with dynamic mixing speed (50-150-50 RPM) was the optimal condition for PFHP. Highest hydrogen yield of 84.7 mL/g TS and highest light conversion efficiency of 36.32% were obtained.

Photo-fermentation biohydrogen production and electrons distribution from dark fermentation effluents under batch, semi-continuous and continuous modes

In this work, the influence of batch, semi-continuous and continuous mode on biohydrogen production from dark fermentation effluents (DFEs) as substrate and electron distribution was investigated. Results indicated a better H2 production performance was obtained in semi-continuous mode. 50% decanting volume ratio (DVR) and 24 h feeding interval time (FIT) were found to be the best condition. Maximum average H2 production rate (HPR) and H2 yield were obtained of 8.44 mL/h and 1386.22 ± 44.23 mL H2/g TOC, respectively. 37.71% substrate electrons partitioning to hydrogen were detected. For continuous mode, more substrate electrons were diverted toward SMPs with the increasing of HRT due to the fact that longer cell retention, more chances were provided for cell lysis. The bad performance in batch mode ascribed to 56.39% substrate electrons were transferred to cell growth and soluble microbial products (SMPs).

Isolation and characterization of a novel photoheterotrophic strain ‘Rubrivivax benzoatilyticus TERI-CHL1’: Photo fermentative hydrogen production from spent effluent

A novel hydrogen producing photosynthetic bacterial strain identified as ‘Rubrivivax benzoatilyticus TERI-CHL1’ was isolated and purified from ‘TERI-CHL’ consortium’ enriched from the sediment samples of Chilika lagoon in Chilika, Odisha, India. Process parameters; pH & temperature, were optimized to enhance hydrogen production performence strain ‘TERI-CHL1’. Acetate, butyrate, sucrose and the spent effluent (DFE: Dark Fermentation effluent) from dark fermentative hydrogen production, explored to use as feed for monitoring hydrogen production performance of ‘TERI-CHL1’ through photo-heterotrophic growth mode. ‘TERI-CHL1’ produced 86.4 mmol/L of cumulative hydrogen from DFE at pH 7 and 37 °C temperature, with 75% H2 yield efficiency. Hydrogen yield efficiency of ‘TERI-CHL1’ from DFE was 8.74 mol per mole of DFE based fermentable organic acids and sugar. This study is the first report on Rubrivivax benzoatilyticus strain ‘TERI-CHL1’ as a promising microbe for valorisation of organic acid rich spent effluent for photofermentative biohydrogen production from Chilika lagoon.

Capacity Analysis of Photo-Fermentation Bio-Hydrogen Production from Different Food Wastes

Food waste is rich in starch or cellulose, which can be utilized as carbon source for fermentation. Hence, in this paper, different food wastes (vegetable, rice, corn, potato) were taken as substrate to evaluate their hydrogen yield potential. The characteristics of fermentation broth, cumulative hydrogen yield, and hydrogen production rate were investigated in the photo-fermentation bio-hydrogen production process. Modified Gompertz Model was utilized to deal with experiment data. Results showed that food waste can be effectively utilized by photosynthetic bacteria. Waste rice was determined to have the best hydrogen production capacity with hydrogen yield of 696 mL, and the maximum hydrogen production rate of 17.71 mL/h, the average hydrogen concentration was 55.78%.

Effect of Substrate Concentration on Photo-Fermentation Bio-Hydrogen Production Process from Starch-Rich Agricultural Leftovers under Oscillation

China has plenty of starch-rich agricultural leftovers, which can be degraded and further utilized for biogas production. Potato, which has more and more cultivated areas, was taken as a substrate. The pH, OD540, biogas yield, hydrogen yield, biogas production rate, and hydrogen production rate were determined to evaluate the effect of substrate concentration on the photo-fermentation bio-hydrogen production process under an oscillation condition. Results showed that the photo-fermentation period was extended to 264 h under oscillation, which was two times longer than the static condition. It was found that 8 g per 100 mL fermentation broth was the most suitable substrate concentration under oscillation, the cumulative hydrogen yield was 510 mL VS−1, and the hydrogen content was 38.36%.

Biohydrogen production through active saccharification and photo-fermentation from alfalfa

Studying biohydrogen production from alfalfa is of practical significance to cleaner production and biomass utilization. The performances of biohydrogen production through active/passive saccharification and photo-fermentation were compared. The effects of initial pH, substrate concentration, and cellulase loading on biohydrogen production from alfalfa by photosynthetic bacteria HAU-M1 were presented. It was found that the maximum hydrogen yield of 55.81 mL/g was achieved at initial pH of 6.90, substrate concentration of 31.23 g/mL, and cellulase loading of 0.13 g/g. Hydrogen yield of active saccharification and photo-fermentation was much higher as compare to passive saccharification and photo-fermentation. Initial pH value showed a more significant influence on photosynthetic bacteria in comparison to cellulase in active saccharification and photo-fermentation biohydrogen production. The low yield of propionic acid suggested that it was an efficient photosynthetic hydrogen production. Photo-fermentation hydrogen production from alfalfa provides a novel path for efficient utilization of alfalfa.

Effects of different pretreatment methods on the structural characteristics, enzymatic saccharification and photo-fermentative bio-hydrogen production performance of corn straw

In this study, the effects of different pretreatment methods, including hydrothermal, acid, alkali, acid-heat, and alkali-heat on the structural characteristics, enzymatic saccharification and photo-fermentative bio-hydrogen production performance of corn straw were investigated. Results revealed that all the studied pretreatments effectively destroyed the corn straw structure and improved its enzymatic saccharification potential. The alkali-heat and alkali pretreatment showed significant advantage in reducing sugars release, and the highest total reducing sugar concentration of 23.07 g/L was obtained under the pretreatment condition of 2% NaOH-Heat. The maximum cumulative hydrogen yield of 137.76 mL/g TS was achieved from 2% NaOH pretreated corn straw, while corn straw pretreated with 4% NaOH-heat had the minimum cumulative hydrogen yield of 44.20 mL/g TS. These results suggest that appropriate pretreatment can effectively destroy the corn straw structure and enhance its enzymatic saccharification and hydrogen production performance.

Evaluation of hydrogen yield potential from Chlorella by photo-fermentation under diverse substrate concentration and enzyme loading

Chlorella is widely distributed, can be cultured in waste water and had short growth cycle. The high carbohydrate composition shows great potential for bioenergy output. In this work, concentrated Chlorella solution was adopted as raw material. Reducing sugar concentration, pH, and cumulative bio-hydrogen yield were taken as indexes, the effects of substrate concentration and enzyme (cellulase or neutral protease) load on photo-fermentation bio-hydrogen production process from microalgae biomass were investigated. Results showed that highest cumulative hydrogen yield was obtained at the optimal substrate concentration of 25 g/L, when the load of cellulase and protease are both 15%, the effect is the best which were 16.65 mL, 29.44 mL, and 43.62 mL, respectively. Results fitted well to the Gompertz model, indicating the feasibility of photo-fermentative bio-hydrogen production from concentrated Chlorella.

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.