Biohythane Production Research Articles

Producing Biohythane from Urban Organic Wastes

This study investigated the advantages of the anaerobic codigestion process of two urban organic waste: the organic fraction of municipal solid wastes and the waste activated sludge produced during biological wastewater treatment. In particular, a comparison between mono and double stage anaerobic digestion for biogas and biohythane (hydrogen and methane) production, respectively, was conducted at thermophilic conditions in a pilot scale rig with a hydraulic retention time of 20 days. Considering yields, the specific gas productions for the single stage process was 490 l biogas per kg TVS fed to the system while in the two stage process hydrogen and methane productions reached average values of 24 LH2 and 570 LCH4 per kg VS fed to the system, respectively. Obtained biohythane, after upgrading, is particularly valuable for the automotive sector contributing to improve the combustion engine performance and to reduce the contaminants emissions in the atmosphere.

Biohythane production of post-hydrothermal liquefaction wastewater: A comparison of two-stage fermentation and catalytic hydrothermal gasification

Developing efficient methods to recover energy from post-hydrothermal liquefaction wastewater (PHW) is critical for scaling up hydrothermal liquefaction (HTL) technology. Here we evaluated two-stage fermentation (TF) and catalytic hydrothermal gasification (CHG) for biohythane production using PHW. A hydrogen yield of 29 mL·g−1 COD and methane yield of 254 mL·g−1 COD were achieved via TF. In comparison, a higher hydrogen yield (116 mL·g−1 COD) and lower methane yield (65 mL·g−1 COD) were achieved during CHG. Further, a techno-economic and sensitivity analysis was conducted. The capital cost and operating cost for TF varied with the different reactor systems. TF with high-rate reactors suggested its promising commercialized application as it had a lower minimum selling price (−0.71 to 2.59 USD per gallon of gasoline equivalent) compared with conventional fossil fuels under both the best and reference market conditions. Compared with TF, CHG was only likely to be profitable under the best case conditions.

Biohythane production in two-stage anaerobic digestion system

Hydrogen (H2) and methane (CH4) are the potential alternative energy carriers with autonomous extensive and viable importance. These fuels could complement the advantages, and discard the disadvantages of each other, if produced simultaneously. Considering their complementary properties, co-production of a mixture of H2 and CH4 in the form of biohythane in two-stage anaerobic digestion (AD) process is gaining more interest than their individual production. Biohythane is a better transportation fuel than compressed natural gas (CNG) in terms of high range of flammability, reduced ignition temperature as well as time, without nitrous oxide (NOx) emissions, improved engine performance without specific modification, etc. Other than production of biohythane, performing two-stage AD is advantageous over one-stage AD due to short HRT, high energy recovery, high COD removal, higher H2 and CH4 yields, and reduced carbon dioxide (CO2) in biogas. For improved biohythane production, various aspects of two-stage AD need to be emphasized. Keeping the facts in mind, the process of two-stage AD along with microbial diversity in comparison to one-stage AD has been discussed in the previous sections of this review. For large scale commercial production, and utilization of biohythane in automobile sector, its execution needs evaluation of process parameters, and problems associated with two-stage AD. Hence, the later part of this review describes the production process of biohythane, concerned microbial diversity, operational process parameters, major challenges and their solutions, applications, and economic evaluation for enhanced production of biohythane.

Biohythane production from sugarcane bagasse and water hyacinth: A way towards promising green energy production

The present study embarks the concept of developing continuous biohythane (biohydrogen followed by biomethane) production from renewable energy sources. Combination of sugarcane bagasse and water hyacinth were used to reduce the use of costly chemicals for fermentation process. The lignin content of sugarcane bagasse was reduced using alkaline hydrogen peroxide pretreatment. The maximum lignin reduction of 89 ± 3% (w/w) was observed at 50 °C and 150 min pretreatment time. Scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy analysis were performed to confirm the lignin removal after pretreatment. Further, the influence of the hydraulic retention time on two stage biohythane production was studied by using combination of pretreated sugarcane bagasse and water hyacinth (1:2 ratio) (soluble COD, 30 ± 2 g/L) in continuous stirrer tank bioreactor. The suitable hydraulic retention time for biohydrogen and biomethane production were found to be 8 h and 10 d, respectively, which gave the maximum hydrogen and methane yield of 303 mL/g COD and 142 mL/g COD, respectively. The continuous biohythane production process increased the overall substrate conversion efficiency up to 86% with the maximum gaseous energy recovery of 8.97 kJ/g COD.

Trace metals supplementation enhanced microbiota and biohythane production by two-stage thermophilic fermentation

The effect of trace metals supplementation into palm oil mill effluent on biohythane production and responsible microbial communities in thermophilic two-stage anaerobic fermentation was investigated. High biohythane yields were linked to Ni/Co/Fe supplementation (10, 6 and 20 mg L−1, respectively) with maximum H2 and CH4 yields of 139 mL H2 gVS−1 and 454 mL CH4 gVS−1, respectively. The Ni/Co/Fe supplementation resulted in higher numbers of Bacillus sp., Clostridium sp. and Thermoanaerobacterium sp. together with increasing hydrogenase expression level leading to increasing hydrogen yields of 90.4%. The numbers of Methanosarcina, Methanomassiliicoccus, and Methanoculleus were enhanced by Ni/Co/Fe addition, accompanied by 21.7% higher methane yields. No correlation between methyl coenzyme-M reductase expression level and methane yields was observed. The Ni/Co/Fe supplementation improved gas production in the two-stage biohythane process via enhancing a number of viable hydrogen-producing bacteria together with hydrogenase activity in H2 stage and enhancing number methanogens in the CH4 stage.

Bio-hythane production from residual biomass of Chlorella sp. biomass through a two-stage anaerobic digestion

Residual Chlorella sp. biomass obtained after anaerobic solid-state fermentation was used to produce bio-hythane. The residual biomass was pretreated using acid, thermal, and acid-thermal methods before their respective hydrolysates were used in dark fermentation followed by the methanogenesis of anaerobic digestion to produce hydrogen and methane, respectively. Pretreatment of the residual biomass using acid and thermal methods did not significantly increase reducing sugar production. However, a maximum reducing sugar content of 28.9 mg-reducing-sugar·g-biomass−1 was attained using an acid-thermal method, resulting in the highest hydrogen and methane yields of 12.5 and 81 mL·g-volatile-solid−1, respectively. This was equivalent to the total energy yield of 3.03 kJ·g-VS−1 or 4.6% energy recovery, based on the heating value of the residual biomass.

Biohythane production from co-digestion of palm oil mill effluent with biomass residues of palm oil mill industry

Biohythane production from co-digestion of palm oil mill effluent with biomass residues of palm oil mill industry

Continuous two-stage anaerobic co-digestion of Skim Latex Serum (SLS) and Rhizoclonium sp. macro-algae for bio-hythane production

Continuous two-stage anaerobic co-digestion of Skim Latex Serum (SLS) and Rhizoclonium sp. macro-algae for bio-hythane production

Performance characteristics of single-stage biohythane production by immobilized anaerobic bacteria

Biohythane produced via dark fermentation is much greener than hythane that is generated using natural gas. Biohythane production using a single-stage system has potential to increase the economic viability since it requires fewer controls than a two-stage system that has individual acidogenic and methanogenic reactors. This single-stage system is an innovative method in producing biohythane. The present work investigated the performance of a mesophilic single-stage system with a batch mode operation to generate biohythane. The reactor was seeded with hydrogenic and methanogenic bacteria (HB and MB), which were entrapped in κ-carrageenan/ gelatin beads (2%/2% w/w) using the dripping method. The energy yield of 0.41 to 1.48 kJ g–1 glucose and the hydrogen content in biohythane (H2/(H2 + CH4)) of 0.35 to 0.69 were obtained. These results indicate that different biohythane compositions would be obtained by regulating the HB/MB bacteria concentration ratio, substrate concentration and cultivation pH. Moreover, a comparison of two-stages and single-stage systems as well as the challenges were also elucidated.

Pilot-scale of biohythane production from palm oil mill effluent by two-stage thermophilic anaerobic fermentation

The pilot-scale of two-stage thermophilic (55 °C) for biohythane production from palm oil mill effluent (POME) was operated at hydraulic retention time (HRT) of 2 days and organic loading rate (OLR) of 27.5 gCOD/L⋅d) for first stage and HRT of 10 days and OLR of 5.5 gCOD/L⋅d for second stage. Biohythane production rate was 1.93 L-gas/L⋅d with biogas containing 11% H2, 37% CO2, and 52% CH4. Recirculation of methane effluent mixed with POME at a ratio of 1:1 can control pH in the first stage at an optimal range of 5.0–6.5. Microbial community in hydrogen stage dominated by Thermoanaerobacterium sp., while methane stage dominated by Methanosarcina sp. The H2/CH4 ratio of biohythane was 0.13–0.18 which suitable for vehicle fuel. Biohythane production from POME could be promising cleaner biofuel with flexible and controllable H2/CH4 ratio.

Fermentative hydrogen and methane co-production from anaerobic co-digestion of organic wastes at high loading rate coupling continuously and sequencing batch digesters.

The anaerobic co-digestion of the most abundant organic wastes was investigated for enhancing biogas production rate and quality. The used feedstock was composed of fruit and vegetable waste (FVW), waste-activated sludge (WAS), olive mill wastewater (OMW) and cattle manure (CM). A considerable methane yield of 340L/kg volatile solid (VS) inlet was obtained using single-stage anaerobic sequencing batch reactors (ASBRs). However, VS biodegradation becomes difficult at high organic loading rate (OLR). Therefore, a continuously stirred tank reactor (CSTR) was integrated to the ASBR for waste pre-digestion. The dark fermentation leads to the improvement of organic matter solubilisation and bio-hydrogen productivity, reaching 0.73L/L/day (H2 content of 49.8%) when pH decreased to 5.8. Therefore, methane productivity increased from 0.6 to 1.86L/L/day in the methanogenic reactor with a better VS biodegradation (91.1%) at high OLR. Furthermore, the bio-hythane production was performed through a controlled biogas recirculation from the dark fermentation stage into the methaniser to reach 842.4L/kg VS inlet. The produced biogas was composed of 8% H2, 28.5% CO2 and 63.5% CH4. Therefore, two-stage anaerobic co-digestion with coupled CH4 and H2 recuperation may be an important contribution for pollution control and high-rate bioenergy recovery (21.1kJ/g VS inlet) from organic wastes.

Process constraints in sustainable bio-hythane production from wastewater: Technical note

The economy of an industrialized country is greatly dependent on fossil fuels. However, these non-renewable sources of energy are nearing the brink of extinction and which have caused serious adverse impacts on the environment. Hydrogen has emerged as a promising alternative and also has the highest calorific value. Bio-hythane is a hydrogen-methane blend can be produced from different organic substrates by two sequential anaerobic stages: a dark fermentation step followed by a second an anaerobic digestion step, for hydrogen and methane production, respectively. Bio-hythane is considered to be promising approach in sustainable energy sector. The advantages of two-stage technology include; high organic removal, high energy recovery and environment friendly. However, current efforts to recover bio-hythane energy from waste are still at bench scale level. The technical constraints in the fermentation must be removed for the indispensable bio-hythane recovery from waste. This short technical note highlights the two-stage fermentation and the technical barriers to be addressed for bio-hythane scale up from waste.

Biohythane production from palm oil mill effluent – a preliminary evaluation of a two-stage anaerobic digestion

Biohythane production from palm oil mill effluent – a preliminary evaluation of a two-stage anaerobic digestion

Feasibility of bio-hythane production by co-digesting skim latex serum (SLS) with palm oil mill effluent (POME) through two-phase anaerobic process

Hydrogenogenic batch fermentation without nutrients addition was investigated at different SLS: POME mixing ratios of 100:0, 95:5, 90:10, 85:15, 80:20, 75:25, 70:30, 65:35, 60:40, 55:45,50:50, and 0:100 (Volatile Solid, VS basis) at initial organic concentrations of 21 and 7 g-VS/L. Satisfactory hydrogen yield of 84.5 ± 0.7 mL H2/g-VSadded was achieved from 7 g-VS/L batch having SLS: POME-VS mixing ratio of 55:45. Adding NaHCO3 3 g/L or 0.43 g-NaHCO3/g-VS) in the two-stage anaerobic system at 7 g-VS/L could provide sufficient buffering capacity. Hydrogenogenic effluent from 7 g-VS/L batch at SLS: POME mixing ratio of 55:45 (VS basis) could further generate rather high methane yield of 311.2 ± 8.0 mL- CH4/g-VSadded in themethanogenic stage.According to the experimental results, bio-hythane approximately 55.5 × 106 m3/year with 21% (V/V) of hydrogen, equivalent to51.0 × 106 l-gasoline could be produced potentially from 3.88 × 106 m3 of mixed SLS and POME through the two-stage anaerobic co-digestion.

Energy recovery from tubular microbial electrolysis cell with stainless steel mesh as cathode

In comparison to the transportation and storage of hydrogen, methane has advantages in the practical application, while the emerging product termed as ‘biohythane’ could be an alternative to pure hydrogen or methane in a new form of energy recovery from microbial electrolysis cell (MEC). However, the cathodic catalyst even for biohythane still bothers the performance and cost of total MEC. Herein, we fabricated the MEC reactor with surrounding stainless steel mesh (SSM) to investigate the feasibility of stainless steel mesh as an alternative to precious metal in biohythane production. The columbic efficiency (CE) of anode was around at 80%, representing the SSM would not limit the activity of anodic biofilm; the SEM image and ATP results accordingly indicated the anodic biofilm was mature and well constructed. The main contribution of methanogens that quantified by qPCR belonged to the hydrogenotrophic group (Methanobacteriales) at cathode. The energy efficiency reached more than 100%, reached up to approximately 150%, potentially suggesting the energetic feasibility of the application to obtain biohythane with SSM in scale-up MEC. Benefiting from the likely tubular configuration, the ohmic resistance of cathode was very low, while the main limitation associated with charge transfer was mainly caused by biofilm formation. The total performances of SSM used in the tubular configuration for biohythane production provide an insight into the implementation of non-precious metal in future scale-up pilot with energy recovery.

Bio-hythane production from cassava residue by two-stage fermentative process with recirculation

The two-stage hythane fermentation of cassava residue low in protein, rich in iron, and deficient in nickel and cobalt, resulted in failure after long-term operation, showing a radical decrease in methane production along with an increase in volatile fatty acids (VFAs) accumulation in the second stage. Based on the gap between theoretical demand and existing content of nutrients, the effect of their additions on hythane fermentation was validated in the repeated batch experiment and continuous experiment. The proliferation of hydrolysis bacteria, acidogens, and hydrogen producing bacteria and methanogens was guaranteed by sufficient N (0.7g/L), S (30mg/L), Ni (1.0mg/L), and Co (1.0mg/L), and the metabolism of a sustainable hythane fermentation was recovered. In this optimal nutrient combination of above trace elements, the highest hythane yield (426m3 hythane with 27.7% of hydrogen from 1ton of cassava residue) was obtained.

Effective control of biohythane composition through operational strategies in an innovative microbial electrolysis cell

Biohythane is a renewable energy fuel composed of methane and hydrogen gas at a certain ratio. Microbial electrolysis cells (MECs) have been employed to produce biohythane but the composition of the produced gas is not well controlled. Herein, an innovative MEC system was developed at a large scale of 19L to investigate biohythane production affected by operational factors. The goal was to understand the interaction between operation and performance towards the development of effective strategies for controlling biohythane composition. To achieve this goal, the performance of this MEC system was studied by varying the key operational factors including anolyte recirculation rate, external resistance, and hydraulic residence time (HRT). It was found that the optimized operational condition for this MEC system included the anolyte recirculation rate of 800mLmin−1, external resistance of 1 Ω, and HRT of 24h. This condition led to the biohythane production of 0.64±0.06Lday−1 with 16.5% H2 proportion and positive net energy recovery of 1.52±0.19kWhday−1. The ANOVA test indicated that the anolyte recirculation rate significantly impacted the methane production rate while the external resistance strongly affected the proportion of hydrogen gas in biohythane. HRT had a minor effect on the biohythane composition but could significantly influence organic removal rate. This is the first study that attempted to use operational factors to control biohythane composition, and its results will provide important implications to formulate control strategies for biohythane production and to scale up MEC systems towards practical applications.

Biohythane production from Chlorella sp. biomass by two-stage thermophilic solid-state anaerobic digestion

Two-stage thermophilic solid state anaerobic digestion (SS-AD) processes for biohythane production from Chlorella sp. biomass was investigated. The hydrogen and methane yield from fresh Chlorella sp. biomass was 124.9 mL H2 gVS−1 and 230.1 mL CH4 gVS−1, respectively, at 16% TS with biodegradation efficiency of 34%. Hydrogen and methane production from hydrothermal pretreated Chlorella sp. biomass was 190.0 mL H2 gVS−1 and 319.8 mL CH4 gVS−1, respectively at 16% TS with biodegradation efficiency of 47%. Pretreatment of Chlorella sp. biomass with hydrothermal follow by two-stage thermophilic SS-AD improved 150% biogas production comparing with fresh biomass. Clostridium sp. was the main bacteria responsible for hydrogen production. Clostridium sp. and Ruminococcus sp. was main bacteria in methane stage, while Methanoculleus sp. and Methanothermobacter sp. was dominated archaea in methane production process. Chlorella sp. biomass with hydrothermal pretreatment has great potential for hydrogen and methane production via two-stage thermophilic SS-AD.

Effects of volatile fatty acids in biohydrogen effluent on biohythane production from palm oil mill effluent under thermophilic condition

Background: Biohydrogen effluent contains a high concentration of volatile fatty acid (VFA) mainly as butyric, acetic, lactic and propionic acids. The presence of various VFAs (mixture VFAs) and their cooperative effects on two-stage biohythane production need to be further studied. The effect of VFA concentrations in biohydrogen effluent of palm oil mill effluent (POME) on methane yield in methane stage of biohythane production was investigated. Results: The methane yield obtained in low VFA loading (0.9 and 1.8 g/L) was 15–20% times greater than that of high VFA loading (3.6 and 4.7 g/L). Butyric acid at high concentrations (8 g/L) has the individual significantly negative effect the methane production process ( P P Geobacillus sp., Thermoanaerobacterium thermosaccharolyticum , Methanoculleus thermophilus and Methanothermobacter delfuvii resulting in low methane yield. Conclusion: Preventing the high concentration of butyric acid, and propionic acid in the hydrogenic effluent could enhance methane production in two-stage anaerobic digestion for biohythane production. Normal 0 false false false ES-CL X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0cm; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Times New Roman; mso-bidi-theme-font:minor-bidi; mso-ansi-language:ES-CL;} Normal 0 false false false EN-US X-NONE TH

Bio-hythane production from microalgae biomass: Key challenges and potential opportunities for algal bio-refineries

The interest in microalgae for wastewater treatment and liquid bio-fuels production (i.e. biodiesel and bioethanol) is steadily increasing due to the energy demand of the ultra-modern technological world. The associated biomass and by-product residues generated from these processes can be utilized as a feedstock in anaerobic fermentation for the production of gaseous bio-fuels. In this context, dark fermentation coupled with anaerobic digestion can be a potential technology for the production of hydrogen and methane from these residual algal biomasses. The mixture of these gaseous bio-fuels, known as hythane, has superior characteristics and is increasingly regarded as an alternative to fossil fuels. This review provides the current developments achieved in the conversion of algal biomass to bio-hythane (H2+CH4).