Fermentative Hydrogen Production Research Articles

Synergistic sodium alginate- and biochar-immobilized cells for enhancing fermentative hydrogen production from food waste.

An immobilized hydrogen-producing consortium investigated biohydrogen production from food waste using a combination of sodium alginate and cassava rhizome biochar. We investigated the effect of varying the biochar concentration from 0 to 3% and the size of immobilized cells from 1 to 7mm. Immobilized cells were prepared using 50% (v/v) enriched hydrogen-producing consortium, 2% (w/v) sodium alginate, and 0 to 3% (w/v) cassava rhizome biochar. The optimal conditions for achieving the highest hydrogen production in the batch fermentation reactor were identified as a biochar concentration of 2% (w/v) and an immobilized cell size of 2mm. The highest hydrogen yield, maximum hydrogen production rate, and lag time recorded were 0.69mmol H2/g-COD, 0.02mmol H2/g-COD.h, and 41.51h, respectively. This research highlights the potential of cassava biochar technology for efficient biohydrogen production from food waste, contributing to renewable energy generation and sustainable waste management.

Biohydrogen production from lignocellulosic hydrolysate: Unveiling the synergistic impact of substrate concentration and furfural inhibition.

Lignocellulosic biomass offers substantial potential as an ideal feedstock for dark fermentative hydrogen production due to its sustainability and cost-effectiveness. The current study examined the influence of furfural on fermentative hydrogen production using lignocellulosic hydrolysate in the presence of furfural. Synthetic lignocellulosic hydrolysate, consisting primarily of 76% xylose, 10% glucose, 9% arabinose, and a mixture of other sugars such as galactose and mannose (85% pentose sugars and 15% hexose sugars), was employed as the substrate. Various substrate concentrations ranging from 2 to 32g/L were tested, along with furfural concentrations of 0, 1, and 2g/L. The investigation aimed to assess the effects of initial substrate concentration, initial furfural concentration, furfural-to-biomass ratio (F/B), and furfural-to-substrate ratio (F/S) on biohydrogen production yields. The maximum specific substrate utilization rates at different substrate concentrations were effectively characterized using Haldane's substrate inhibition model. Among the tested concentrations, the 16g/L emerged as the optimal substrate concentration. The initial furfural concentration was identified as the most significant parameter impacting biohydrogen production, with complete inhibition observed at a furfural concentration of 2g/L. Higher F/S ratios at substrate concentrations ranging from 2 to 16g/L resulted in reduced maximum specific hydrogen production rates (MSHPR) and hydrogen yields. Substrate inhibition was observed at 24g/L and 32g/L. Lactate was the predominant metabolite in all batches containing 2-g/L furfural, as well as in batches with 1-g/L furfural and substrate concentrations of 24 and 32g/L. Furfural at a concentration of 1g/L was not inhibitory in any of the batches. Overall, the mixed cultures in this study could efficiently produce hydrogen from lignocellulosic hydrolysates and degrade furfural, providing new insights into fermentative hydrogen-producing bacteria with furfural tolerance.

Greenhouse Gas Emissions and Net Energy Production of Dark Fermentation from Food Waste Followed by Anaerobic Digestion

There are diverse estimations regarding the carbon reduction effects of alternative hydrogen production technologies. This study assessed the greenhouse gas (GHG) emissions and energy balance of a two-stage process combining dark fermentative hydrogen production and anaerobic digestion from food waste using the cradle-to-gate life cycle assessment (LCA). The system boundary included collection and transportation, pretreatment and feedstock storage, dark fermentation, H2 purification, anaerobic digestion and heat and power generation and the estimated GHG emission was compared with a single anaerobic digestion of food waste. GHG emission of the biohydrogen production was estimated as 2.48 kg CO₂-eq per kg H₂ without considering avoided emissions from heat and power generation. The environmental impacts were majorly influenced by electricity use. The net energy ratio of the two-stage process was calculated to be 8.18, confirming a net energy gain and the potential GHG emission avoidance for electricity and heat use. Given that the single-stage anaerobic digestion of 16 tons of food waste is replaced by the two-stage dark fermentation process, 76.6 kg CO₂-eq would be avoided. Sensitivity analysis revealed that energy-saving strategies are the most sensitive factors for achieving positive net energy production and low global warming potential.

Combined bioprocess for fermentative hydrogen production from food waste: A review

Bio hydrogen is a cheaper, sustainable and safer source to produce fuel comparable to energy obtained from fossil fuels. There are many experimental methods to produce bio hydrogen using food wastes as substrates that are acted upon by specific bacterial and fungal strains. Some of the methods include batch-dark fermentation, solid-state dark fermentation, dark-anaerobic hydrogen fermentation and integrated light-dark fermentation. Different food wastes are used in these fermentation processes such as kitchen food waste, potatoes peels, sugary waste water, fish, meats, grains, cassava residues, corn pulp and starchy solution etc. These food wastes are rich source of main raw materials that are required for bio hydrogen production such as cellulose, carbohydrates, fats, proteins, lipids, starch, phosphorus, volatile solids, Published experimental and research approaches revealed that the use of mixed dark-photo fermentative bacterial consortium in flat photo bioreactors and fermenters resulted in higher yield. Combined dark-photo fermentation is an advanced and promising strategy for increasing overall yield of bio hydrogen.

Effects of Sugar Beet Pulp Pretreatment Methods on Hydrogen Production by Dark Fermentation

Methane and hydrogen generated from waste and biomass are renewable resources, which may successfully replace traditional fossil fuels. This paper investigates the enhancement effect of lignocellulosic biomass pretreatment on dark fermentative hydrogen production from sugar beet pulp (SBP). The results showed that sugar beet pulp after pretreatment contained significant amounts of unfermented sugars (mainly glucose, arabinose, galactose, and raffinose), and, therefore, represented an attractive substrate for methane and hydrogen production. The greatest methane yield (495 dm3 CH4/kg VS) was achieved from sugar beet pulp after alkaline pretreatment. High methane production of up to 445 dm3 CH4/kg VS was also obtained using acidic and enzymatic hydrolysis as a preliminary treatment of the pulp. All the pretreatment methods also resulted in the enhancement of hydrogen yield with the highest value of 229 dm3 H2/kg VS achieved using acid hydrolysis compared with 17 dm3 H2/kg VS for raw material subjected to digestion.

Effect of copper on fermentative hydrogen production from sewage sludge: Insights into working mechanisms

The effect of Copper (Cu) on fermentative hydrogen production from sewage sludge (SSL) was firstly explored, and glucose was chosen as typical substrate to make a comparison. Results showed that the stimulative dosages of Cu on hydrogen production from glucose and SSL were 20–60 mg/L and 20–100 mg/L, respectively. The stimulation was more significant to SSL (6.3–43.8 %) than glucose (4.8–16.1 %). 500–1000 mg/L Cu posed obvious inhibition to hydrogen production, and the inhibition was more significant to glucose (80.6–91.9 %) than SSL (25.0–37.5 %), which was due to the protective effect of SSL to hydrogen producers from adsorbing Cu. The exposure enriched the Cu-resistant microorganisms like genus Aeromonas, Comamonas, Pseudomonas and Dechloromonas. Metabolic analysis shows that low dosages of Cu stimulated hydrogen production by strengthening the formate decomposition process, and weakening the lactate formation and homoacetogenesis processes, while high dosages of Cu inhibited hydrogen production by weakening all hydrogen-producing processes including formate decomposition, ferredoxin hydrogenation and glucose decomposition processes.

Enhancing dark fermentative hydrogen production from wheat straw through synergistic effects of active electric fields and enzymatic hydrolysis pretreatment

Hydrogen, a clean and sustainable energy source, faces challenges from energy-intensive pre-processing technologies. This study explores the synergistic enhancement of active electric fields on enzymolysis of wheat straw and hydrogen production through dark fermentation. The active electric field enzymolysis system improved the adsorption capacity of wheat straw to cellulase, increasing cellulase activity by 18.0 %, causing a 39.1 % increase in reducing sugar content. In the active fermentation system, Clostridium_sensu_stricto_1 activity was enhanced in the first stage, increasing hydrogenase activity by 23.0 %, prolonging the first hydrogen production peak. Elevated reducing sugars were observed in the second stage, with Prevotella_9 and Bacteroides becoming the dominant hydrogen-producing bacteria in the third stage, leading to a second hydrogen production peak. Overall, cumulative hydrogen production was enhanced by 50.9 % compared to the control. The synergistic pretreatment with an active electric field and cellulase provides a novel approach for efficiently utilizing wheat straw.

Sustainable duckweed biomass valorization for dark fermentative hydrogen production: Process evaluation under meso- and thermophilic operations

Aquatic plants are rich in biomass and contain good amounts of carbohydrates and proteins which are amenable for valorization to generate bioenergy. Duckweed is rich in proteins and carbohydrates that grow abundantly in contaminated waterbodies, which is now tested for as a substrate for biohydrogen production. Dark-fermentative hydrogen production was done by hydrothermal pretreatment of duckweed biomass under 15 lbs pressure, evaluated under three different operating temperatures that cover mesophilic (35 °C) and thermophilic conditions (50 and 55°C). The study resulted in the maximum hydrogen production rate of 0.97 mmol/day in batch culture (160 mL) from 55 °C that was found superior to 50 °C (0.84 mmol/day) and 35 °C (0.38 mmol/day) operations. From the 7 days of operation, under uncontrolled pH conditions, substrate (chemical oxygen demand, COD) utilization was 57.27 %, which is higher than in mesophilic conditions (50.67 %). Efficient hydrolysate conversion was noticed with thermophilic conditions, especially under operation at 55 °C (416 mL H2/g of biomass) than mesophilic conditions (144 mL H2/g of biomass) suggesting that duckweed can be dependable biomass for hydrogen production, and the dark-fermentation can be an appropriate solution of aquatic weed biomass management in a sustainable approach.

New insights on waste mixing for enhanced fermentative hydrogen production

Co-fermentation can differently impact H2 production, with positive or negative interactions observed. Positive interactions were usually attributed to a balanced composition and improved buffer capacity. However, the impact of co-fermentation on microbial communities (H2-producing and H2-consuming bacteria) remains unexplored. This work aimed to deepen the interaction mechanisms observed in co-fermentation targeting microbial communities with an innovative focus on H2-consuming bacteria (homoacetogens). The H2 production of seven mixtures (food waste fractions and rye silage) and individual performances were compared by Biochemical Hydrogen Potential (BHP). Final microbial communities were characterized by sequencing and qPCR. A positive correlation between H2 yield and Soluble and Easily Extractible Sugars (SEES) content was observed for all the substrates (R² = 0.79), confirming this correlation not only for individual substrates but also mixtures. Positive interactions were observed for most of the mixtures, with a H2 yield significantly higher (16–37 %) than expected. The faster H2 production observed in mixtures (2.6 times faster) was correlated to the selection of Clostridiaceae_1 family (final relative abundance of 90–98 %) and decline of homoacetogens. It is therefore essential to further understand the microbial communities’ dynamics in co-fermentation to develop efficient fermentation systems.

Biohydrogen production by a novel strain Petroclostridium sp. X23 isolated from the production water of oil reservoirs

Biohydrogen production from H2-producing has been considered a promising alternative for the replacement of fossil fuels. However, the mechanisms that affect the H2-producing capacities of wild-type strains remain largely elusive. To explore the capabilities of biohydrogen production from microorganisms in the deep subsurface oil-reservoir environment, we isolated an H2-producing bacteria identified as the genus Petroclostridium from a long-term methanogenic crude oil-degrading enrichment culture of the production water from oil reservoir. The impact of various temperature, pH, and glucose concentrations on hydrogen production by Petroclostridium sp. X23 was investigated. Under the conditions of 37 °C, initial pH 8.0, and glucose concentration of 4 g/L, the strain X23 achieved its maximum hydrogen yield at 1.82 ± 0.12 mol H2/mol glucose. When compared to the previously reported strain SK-Y3, X23 exhibited enhanced H2-producing ability, with lesser energy biomass production. Comparative genomic analysis revealed that the genome of X23 contains more genes associated with hydrogen generation than SK-Y3. These findings proposed Petroclostridium sp. X23 is a potential candidate for dark fermentative hydrogen production under alkaline and mesophilic conditions. It also increased our knowledge of genotypes related to high H2-producing capability, which may provide instructions for future selection of high-yielding strains and reasonable metabolic engineering of wild-type H2-producing strains.

Specific Organic Loading Rate Control for Improving Fermentative Hydrogen Production

Inhibiting homoacetogens is one of the main challenges in fermentative hydrogen production because these hydrogen consumers have similar growth features to hydrogen producers. Homoacetogens have been related to the excessive accumulation of biomass in fermentative reactors. Therefore, a suitable food/microorganism ratio has the potential to minimize the homoacetogenic activity. In this work, the specific organic loading rate (SOLR) was controlled in two fermentative fixed-bed up-flow reactors through scheduled biomass discharges. Reactors were differentiated by the bed arrangement, namely, packed and structured conformation. The SOLR decay along the time in both reactors was previously simulated according to the literature data. The volume and volatile suspended solids (VSS) concentration of discharges was estimated from the first discharge, and then additional discharges were planned. Biomass discharges removed 21% of the total biomass produced in the reactors, maintaining SOLR values of 3.0 ± 0.4 and 3.9 ± 0.5 g sucrose g−1 VSS d−1 in the packed-bed and structured-bed reactors, respectively. Such a control of the SOLR enabled continuous and stable hydrogen production at 2.2 ± 0.2 L H2 L−1 d−1 in the packed-bed reactor and 1.0 ± 0.3 L H2 L−1 d−1 in the structured-bed one. Controlling biomass was demonstrated to be a suitable strategy for keeping the continuous hydrogen production, although the fermentative activity was impaired in the structured-bed reactor. The homoacetogenic was partially inhibited, accounting for no more than 30% of the total acetic acid produced in the reactor. Overall, the high amount of attached biomass in the packed-bed reactor provided more robustness to the system, offsetting the periodic suspended biomass losses via the planned discharges. Better characterizing both the VSS composition (aiming to differentiate cells from polymeric substances) and the bed hydrodynamics could be useful to optimize the online SOLR control.

Enhancing biohydrogen production from xylose through natural FeS2 ore: Mechanistic insights

In this study, we investigated the advantages of utilizing natural FeS2 ore in the context of dark fermentative hydrogen production within a fermentation system employing heat-treated anaerobic granular sludge with xylose as the carbon source. The results demonstrated a significant improvement in both hydrogen production and the maximum rate, with increases of 2.58 and 4.2 times, respectively. Moreover, the presence of FeS2 ore led to a reduction in lag time by more than 2–3 h. The enhanced biohydrogen production performance was attributed to factors such as the intracellular NADH/NAD+ ratio, redox-active components of extracellular polymeric substances, secreted flavins, as well as the presence of hydrogenase and nitrogenase. Furthermore, the FeS2 ore served as a direct electron donor and acceptor during biohydrogen production. This study shed light on the underlying mechanisms contributing to the improved performance of biohydrogen production from xylose during dark fermentation through the supplementation of natural FeS2 ore.

Inhibition of norfloxacin on fermentative hydrogen production: Performance evaluation and metagenomic analysis

Toxic chemicals can inhibit the dark fermentation process for renewable biohydrogen production. Norfloxacin (NOR), a typical antibiotic, is present in various feedstocks of dark fermentation, which has excellent antibacterial properties. It is hypothesized that NOR could cause adverse effects on fermentative hydrogen production, while current understanding of this subject is scare. This study investigated the potential inhibitory effect of NOR on dark hydrogen fermentation, and explored the underlying mechanisms from the perspectives of bacterial community structure and functional gene abundance. The results showed that NOR significantly reduced the hydrogen-producing capacity upon exposure to concentrations exceeding 10 mg/L. The hydrogen yield decreased from 1.56 to 0.27 H2/mol-glucose at NOR concentrations of 50 mg/L. NOR also prolonged the hydrogen-producing lag period. Bacterial community analysis revealed that NOR reduced the abundance of high-yielding H2-generating bacteria, such as Clostridium sp., while increasing the abundance of H2-consuming bacteria (e.g. Enterococcus sp.). Metagenomic analysis further indicated that crucial genes involved in glycolysis (e.g. HK, tal-pgi, pfk and PK) and hydrogen formation (e.g. por and E1.12.7.2) were remarkably downregulated under NOR exposure, essentially causing the inhibition of hydrogen production. This study contributes to a better understanding of how antibiotics inhibit dark hydrogen fermentation and provides a theoretical basis for reducing potential inhibitory effects.

An Updated Review of Recent Applications and Perspectives of Hydrogen Production from Biomass by Fermentation: A Comprehensive Analysis

Fermentation is an oxygen-free biological process that produces hydrogen, a clean, renewable energy source with the potential to power a low-carbon economy. Bibliometric analysis is crucial in academic research to evaluate scientific production, identify trends and contributors, and map the development of a field, providing valuable information to guide researchers and promote scientific innovation. This review provides an advanced bibliometric analysis and a future perspective on fermentation for hydrogen production. By searching WoS, we evaluated and refined 62,087 articles to 4493 articles. This allowed us to identify the most important journals, countries, institutions, and authors in the field. In addition, the ten most cited articles and the dominant research areas were identified. A keyword analysis revealed five research clusters that illustrate where research is progressing. The outlook indicates that a deeper understanding of microbiology and support from energy policy will drive the development of hydrogen from fermentation.

ADM1-Based Modeling of Biohydrogen Production through Anaerobic Co-Digestion of Agro-Industrial Wastes in a Continuous-Flow Stirred-Tank Reactor System

Biological treatment is a promising alternative for waste management considering the environmentally sustainable concept that the European Union demands. In this direction, anaerobic digestion comprises a viable waste treatment process, producing high energy-carrier gases such as biomethane and biohydrogen under certain operating conditions. The mathematical modeling of this bioprocess can be used as a valuable tool for process scale-up with cost-effective implications. The scope of this work was the evaluation of the well-established Anaerobic Digestion Model 1 (ADM1) for use in two-stage anaerobic digestion of agro-industrial waste. Certain equations for the description of the metabolic pathways for lactate and bioethanol accumulation were implemented in the existing mechanistic model in order to enhance the model’s accuracy. The model presents a high estimation ability regarding the final product (H2 and biogas) reaching the same maximum value for the theoretical as the experimental data of these products (0.0012 and 0.0036 m3/d, respectively). The adapted ADM1 emerges as a useful instrument for designing anaerobic co-digestion processes with the goal of achieving high yields in fermentative hydrogen production, considering mixed biomass growth mechanisms.

Combination of Physics‐Based Model and Artificial Intelligence for Rapid Simulation and Optimization of Dark Fermentative Hydrogen Production From Water Hyacinth

Dark fermentative hydrogen (H2) production from water hyacinth (WH) is considered a potentially sustainable process that helps minimize this weed’s harmful effects on the ecosystem and dependence on fossil fuels. To create a quick and precise tool for simulating and optimizing this process, this study applied the combination of the physics‐based model and artificial intelligence approaches for the first time. The physics‐based model was used as a computational experimental dataset generator to save time and cost in acquiring experimental data. Such a synthetic dataset was used to train the artificial neural network (ANN) model, which can predict the performance of dark fermentation fed with water hyacinth (DF@WH) in a fraction of the time. The particle swarm optimization (PSO) algorithm was then integrated to identify the ideal conditions for DF@WH. H2 productivity and total energy recovery were selected as objectives based on basic operating parameters such as substrate concentration, initial pH, temperature, and operating time. The optimization results revealed that the maximum values of H2 productivity (i.e., the maximum yield of 266.8 mL/g‐TS and the maximum rate of 80.5 mL/L/h) and energy efficiency (i.e., 11.4%) cannot be achieved simultaneously under a specific optimal condition. Instead, when these targets were considered equally important, the balance optimal condition was determined at a substrate concentration of 8.9 g‐TS/L, an initial pH of 6.5, a temperature of 33.9°C, and an operating time of 28.2 h. Under such conditions, H2 productivity can be achieved with a yield of 200.2 mL/g‐TS at a production rate of 62.9 mL/L/h and a total energy recovery of 11.0%.

Dark Fermentative Hydrogen Production from Spent Coffee Grounds Hydrolysate by Clostridium butyricum

Dark Fermentative Hydrogen Production from Spent Coffee Grounds Hydrolysate by Clostridium butyricum

Environmental impact assessment of a combined bioprocess for hydrogen production from food waste

With the growth of population and the development of economy, the food waste (FW) and energy shortage issues are getting great attentions. In this study, the environmental performance of a biorefinery of enzymatic hydrolysis and fermentation for hydrogen production from FW (FW-H2) was investigated by life cycle assessment (LCA) in terms of greenhouse gas (GHG) emissions and non-renewable energy use (NREU). It was found that the gas compression, electricity and FW transport were the major environmental hotspots in the FW-H2 process. The GHG emissions of 10.1 kg CO2 eq and NREU of 104 MJ were obtained from per kg hydrogen production through the whole process. The environmental impacts of the FW-H2 process were lower than the conventional processes for hydrogen production, such as steam methane reforming and electrolysis with grid. Sensitivity analysis demonstrated that the efforts in environmental hotspots, especially in gas compression, could result in the improvement of environmental impacts of the FW-H2 process. The GHG emissions and NREU could reduce to 89.2 % and 89.4 % with a 20 % reduction of energy consumption for gas compression. Different allocation methods (economic allocation, mass allocation, no allocation and system expansion method) applied for LCA analysis could provide a significant influence of environmental impacts in the FW-H2 process. The results obtained from this study could lead to further research into resource recycling from waste and would ultimately contribute to the development of circular economy.

Improved estimation of dark fermentation biohydrogen production utilizing a robust categorical boosting machine-learning algorithm

Dark fermentation is attracting great attention due to some capabilities such as wastewater treatment and biofuel production. In this study, the performance of different machine learning algorithms, including Bagging-Extreme Gradient Boosting (BagXGBoost), Categorical Boosting (CatBoost), K Nearest Neighborhood (KNN), Light Gradient Boosting Machine (LightGBM), and Decision Trees (DT) in the prediction of biohydrogen production from wastewater during dark fermentation is investigated. Effect of parameters Ni, Fe, biomass, pH, chemical oxygen demand (COD), HRT, acetate, ethanol, butyrate, and acetate/butyrate ratio as inputs were considered for the model development. A databank with 208 data points was culled from the literature. For the validation of the proposed models, various statistical criteria were determined. CatBoost and BagXGBoost exhibited superior performance in predicting fermentative hydrogen (H2) production. Shapley additive explanations were used for relative analysis, revealing the highest absolute SHAP values of 1.1, 1, and 0.07 for COD, nickel, and butyrate, respectively, highlighting their significance in H2 production. The insights gained from this study can contribute to further optimization of the dark biohydrogen fermentation process.

Polydimethyldiallylammonium chloride inhibits dark fermentative hydrogen production from waste activated sludge

Polydimethyldiallylammonium chloride (PDDA) is an excellent flocculant for wastewater purification and sludge dewatering, but whether it poses a threat to hydrogen production from waste activated sludge is not known. In this study, the effect and underlying mechanism of PDDA on the dark fermentation of sludge was investigated. The results showed that PDDA reduced cumulative hydrogen production from 3.8±0.1 to 2.4±0.1 mL/g volatile suspended solids at 40 g/kg total suspended solids. PDDA impeded the dark fermentation process by inhibiting the activity of key enzymes, presenting a stronger inhibitory effect on the hydrogen production process than the hydrogen consumption process. Additionally, PDDA inhibited Firmicutes by enriching other microorganisms, thereby impeding hydrogen production via the acetate pathway. This study deepens the understanding of the potential effects of PDDA on sludge treatment and provides a theoretical basis for alleviating the negative effects of quaternary ammonium-based cationic flocculants.