Enhanced Biogas Production Research Articles

Evaluating the role of salinity in enhanced biogas production from two-stage anaerobic digestion of food waste by zero-valent iron

Salts including NaCl are the most common food flavoring agents so they are often accumulated in food waste (FW) and have potential impact on anaerobic digestion (AD) of FW. In this study, the enhanced biogas production from two-stage anaerobic digestion (TSAD) of FW by microscale zero-valent iron (ZVI) under different salinity (3, 6, 9, and 15 g NaCl/L) was evaluated. Under salinity stress, ZVI becomes a continue-release electron donor due to the enhanced corrosion and dissolution effect and the slow-down surface passivation, further improving the performance of TSAD. Experimental results revealed that the biogas production including H2 and CH4 from TSAD with 10 g/L ZVI addition was promoted under salinity stress. The maximum H2 and CH4 yield (303.38 mL H2/g-VS and 253.84 mL CH4/g-VS) were observed at the salinity 9 g NaCl/L. Compared with that of zero salinity, they increased by 40.94% and 318.46%, respectively. Additionally, Sedimentibacter, an exoelectrogen that can participate in the direct interspecies electron transfer, also exhibited the highest relative abundance (34.96%) at the salinity 9 g NaCl/L. These findings obtained in this study might be of great importance for understanding the influence of salinity on the enhanced AD by ZVI.

Characterization of Coffee-Pulp Biochar as an Additive to Enhance Biogas Production from Coffee Mucilage

Biogas has been effectively produced from solid as well as liquid biomass waste through anaerobic digestion (AD). It has been proved that AD is the most efficient technology and less environmental effect in converting biomass to biogas. However, it is challenging that the rate of biogas production might slow down by many factors. It requires continues research in order to overcome the problem, such as by adding an additive. The use of several additives for AD has received great attention due to the positive influence in improving the production performance of biogas in terms of process stability and efficiency, and production capacity. Among all types of additives, carbon material in the form of bio-char has been considered as the most profitable due to low cost and easy to produce from various carbon source materials. This study aimed to determine the characteristics of coffee pulp bio-char which will be used as an additive in biogas production from coffee mucilage by the AD method. Coffee pulp biomass and coffee mucilage were obtained from Aceh Tengah, Indonesia. Preparation of bio-char was carried out by washing and soaking of the coffee pulp with tap water for 24 hours, then drying under the sun for three days. Carbonization of dried coffee pulp was then performed using a pilot plant-scale pyrolysis reactor at temperature of 400 °C for 60 minutes. Resulting biochar was then ground and sieved to 60 mesh size. Based on to proximate analysis result, it was found that the moisture, ash, volatile matter, and fixed carbon contents were respectively 1.98%, 11.93%, 42.36%, and 43.72%. N2-physisorption analysis of coffee-pulp bio-char suggested pore volume of 0.21 cm3/g. From BET calculation method it was found that the surface area was 224.1 m²/g. This high surface area is beneficial for providing sheltered spaces for microbes to attach and hindering them against metabolic inhibitors. The effect of adding biochar additives from coffee skin waste in the anaerobic digestion process of coffee mucilage waste provides significant results on the yield of biogas products. The yield of biogas products increased by 225% with the addition of 15 gr/L of biochar coffee pulp.

Feeding strategy determine flexible biogas via shaping microbial abundance and interaction in anaerobic digestion

The optimization of anaerobic digestion systems for enhanced biogas production is reliant on the manipulation of feeding regimes and organic loading. However, the impact of these operations on the microbiota remains unclear. Here, the effects of three distinct feeding regimes (once daily, every 2nd day, and every 3rd day) with two different loading amounts (300 g and 500 g) were investigated in 2 continuously stirred tank reactors treating swine manure. Results indicated that the high organic loading (500 g daily feeding) resulted in increased biogas and methane production, albeit with reduced archaeal alpha diversity. Furthermore, a significant alteration in species distribution was observed with sudden feeding regime changes (300 g every 2nd day) and higher organic loading. Wherein, the core species determined the methane production regarding the different organic loading. The resultant species turnover likely drove the increased biogas production while species loss contributed to the fluctuation of biogas production in intermittent feeding regimes. Despite a decrease in positive connections with high organic loading, the connectivity of Methanosarcinaceae with bacteria increased, thus ensuring higher biogas production. In conclusion, the present study underscores the association between feeding strategies and elevated levels of organic loading with regards to the interdependence between methanogenic microorganisms and keystone bacterial populations. As a consequence, this interplay exerts a discernible influence on the biogas production process.

Enhancing biogas production from food waste and water hyacinth: effect of co-substrates and inoculum ratios

Enhancing biogas production from food waste and water hyacinth: effect of co-substrates and inoculum ratios

Anaerobic co-digestion of pressmud with vegetable waste in batch reactor for enhanced biogas production

Anaerobic co-digestion of pressmud with vegetable waste in batch reactor for enhanced biogas production

Influence of Mesophilic Bacteria Inoculation with Chicken Manure for Biogas Production Enhancement in Anaerobic Digestion (AD) Process

The objective of this study is to investigate biogas production by anaerobic digestion using mesophilic bacteria mixed with Palm Oil Mill Effluent (POME). This project aims to determine the volume of biogas generation and volatile fatty acid (VFA) production from chicken manure via the anaerobic digestion process. Anaerobic digestion (AD) of chicken manure (CM) often faces obstacles, including high total ammonia nitrogen (TAN) concentration, inorganic soil particles, and wood chips. The digestion process was carried under batch mode conditions in Scott bottles of 1.0 L active volume. The bottles were immersed in a water bath to control their temperature at 37℃. The characteristics of total solid, volatile solid of mass fraction, pH, and temperature on the amount of biogas produced were studied. The investigation showed that biogas production can be enhanced by inoculation of another material. The optimum biogas composition in the AD system was recorded by Inoculum I, which was achieved on Day 2 at 560 mL/L. The highest cumulative methane yield was observed in the leachate with Inoculum (I), which was 8976 mL/gVS, while the CML produced 4 mL/g VS. The anaerobic digestion (AD) process augmented with inoculum demonstrated heightened efficacy in biogas generation and VFA concentration reduction during the acidogenic phase, surpassing the observed performance in chicken manure leachate.

Biocatalyst enhanced biogas production from food and fruit waste through anaerobic digestion

In recent years, the world has faced the adverse effects of global warming and waste management issues. Food waste is one of the major constituents of solid waste. Currently, the world is in the throes of finding an alternative source of fossil fuels, which could lower the energy demand and bring about a pollution-free environment. The stability of anaerobic digestion is significantly influenced by trace elements (TE), which are micronutrients for microbes. Experimental measurements were made of the effects of trace metals (cobalt (Co), nickel (Ni), magnetite (Fe2+Fe3+2O4) and biochar) on mesophilic and thermophilic anaerobic digestion of food waste. The study's major significance is identifying the potential catalyst for the anaerobic digestion system and achieving the best production efficiency. Adding micronutrients increased biogas generation, but it was hampered by the excessive addition of trace metalsthe excessive addition of trace metals hampered it. More biogas was produced when Co was added. We have achieved 42% of methane production with 28 days of hydraulic retention time. The findings can provide quantitative data on the replenishment of trace metals for efficient anaerobic digestion. This work presents novel information about the trace elements and their enhancement inside the biodigester for kitchen and fruit wastes.

Biogas Production from Palm Oil Mill Effluent at Low pH

The palm oil industry in Malaysia has aided our economy, but with any thriving industry comes the baggage of industrial waste. This paper focuses on palm oil mill effluent (POME), a waste product formed by palm oil milling operations. The objective of this paper is to evaluate the ability of POME to generate biogas through acid and heat pre-treatment methods. The feasibility of producing biogas at pH levels lower than 5 was investigated. The inoculum is effective microbe 1 (EM1), and the substrate is a liquid POME. Hydrochloric and phosphoric acid were used in this study, and the effect of low initial pH on biogas generation was investigated. The results show that POME alone produced the highest biogas volume (20.1 Nml). However, POME incubated with activated EM1 inoculant at low pH (3.74) generated consistent biogas during 57.75 hours of digestion. In conclusion, the EM1 is a good source of inoculum for POME treatment at low pH, with no pre-treatment required. The pre-treatment methods proposed in this study could have opened new doors for bio-renewable energy research, particularly in agricultural biomass, since substrate pre-treatment can enhance biogas production.

Enhancing biogas production from chicken manure through vacuum stripping of digestate

Enhancing biogas production from chicken manure through vacuum stripping of digestate

Enhancement of biogas production from Market Yard Vegetable Waste using biological pre-hydrolysis—a pilot scale

Enhancement of biogas production from Market Yard Vegetable Waste using biological pre-hydrolysis—a pilot scale

A novel strategy for integration of oxidation within advanced thermal hydrolysis of sludge

Due to its environmental impact, the growing production of sewage sludge is a prime concern for wastewater treatment plants. In this study, advanced thermal hydrolysis, the combination of thermal hydrolysis and oxygen, was examined to enhance biogas production and overcome the disadvantages of thermal hydrolysis, including sludge colour, high energy consumption, and high level of ammonia concentration in the treated sludge. A mixture of 55 % primary sludge and 45 % waste activated sludge was pre-treated using advanced thermal hydrolysis at 100, 115, 130, and 145 °C with a processing time varied from 5 to 30 min and oxygen pressure from 10 to 30 bar before anaerobic digestion. Advanced thermal hydrolysis process at 145 °C 15 min 20 bar O₂ is the condition that provided the highest biogas yield (439.6 mL/g VS added). At this treatment condition, the concentration of ammonia nitrogen and propionic acid in the treated sludge was sufficiently low (approximately 302 mg/L and 559.7 mg/L, respectively) to minimise adverse effects on anaerobic digestion.

Effect of thermal and NaOH pretreatment on water hyacinth to enhance the biogas production.

Water hyacinth (WH) is used as the substrate for biogas production due to its high lignocellulosic composition and natural abundance. The present study used thermal and chemical (alkali) pretreatment techniques to enhance biogas production from water hyacinth used as a substrate by anaerobic digestion. Thermal pretreatment was done using an autoclave at 121 °C and 15 lb (2 bar) pressure and alkali pretreatment by NaOH at two concentrations (2% and 5% w/v). The inoculum:substrate ratio for biogas production was 2:1, where cow dung was used as inoculum. Results indicated that the pretreatments increased biomass degradability and improved biogas production. Water hyacinth pretreated with 5% NaOH produced the highest amount of biogas (142.61 L/Kg VS) with a maximum methane content of 64.59%. The present study found that alkali pretreatment can modify the chemical structure and enhance WH hydrolysis, leading to enhanced energy production.

Enhancing biogas production from cheese whey using Zero-Valent Iron: A comparative analysis of batch and semi-continuous operation modes

Cheese whey (CW) is the primary by-product of dairy industries, and its anaerobic treatment presents several challenges. Among these is the production of high levels of volatile fatty acids (VFAs) due to rapid biodegradation, which leads to a drop in pH and adversely impacts methanogenesis. This study aims to evaluate the impact of Zero-Valent Iron (ZVI) on the anaerobic digestion of CW under both semi-continuous and batch conditions. Since ZVI generates H2 and increases pH under soluble CO2 conditions, the study also focuses on the effects of ZVI on solubilization/hydrolysis, acidification, and microbial response. Three anaerobic bioreactors (R25-PZVI with 25 g/L powder ZVI, R50-SZVI with 50 g/L scrap ZVI, and R-Control without ZVI), at semi-continuous mode, treated cheese whey at varying organic loading rates. After 118 days, R25-PZVI showed the highest CH4 yield and best COD removal, followed by R50-SZVI. Despite NaOH additions, it maintained a lower VFA/ALK ratio than the control. Under semi-continuous mode, CH4 composition in R25-PZVI was 59%, rising to over 95% under batch conditions due to the higher pressure and subsequent solubilization of H2 and CO2. The ZVI mainly impacted methanogenesis and acidogenesis and not solubilization/hydrolysis. 25-PZVI's superior performance was due to its increased H2 generation and alkalinity over 50 g/L SZVI, as was found in the abiotic test. Under semi-continuous conditions, Methanobacterium (a hydrogenotrophic methanogen) and Methanosarcina were the dominant genera in the R25-PZVI reactor. Under batch conditions, Methanothrix displayed a higher abundance, which explained the increased acetic acid utilization.

Enhanced Biogas Production from Rice Husks and Okra Stalks by Co-digestion with Ostrich Dung and Cow Manure

In this study, two sides were studied. First one included single and combined pretreatment which were performed to treat milled rice husks compared to increase the production of biogas untreated rice husks. The other side included investigate the effect of two types of mixing: mixing rice husks and okra stalks using three mixing ratios inoculated with ostrich dung compared to rice husks and okra stalks inoculated with ostrich dung separately and mixing ostrich dung and cow manure using three mixing ratios with rice husks compared to using rice husks inoculated with ostrich dung and cow manure separately. The ten reactors, which were carried out in this study, were in batch mode. Single pretreatment included hydrothermal and oxidative pretreatment with 50% (v/v) H2O2, while combined pretreatment consisted of both hydrothermal and H2O2 pretreatment. The cow manure was used as inoculum in this anaerobic co-digestion process. The results clarified that the increase of biogas productions were by 5.42%, 48.05%, and 59.07% for hydrothermal, H2O2, and combined pretreatment of hydrothermal and H2O2, respectively. For first mixing, 25:75 ratio (rice husks: okra stalks) was better than other ratios in the production of biogas (48.77 ml/g VS). In the second case of mixing, 75:25 ratio (ostrich dung: cow manure) was better than other ratios in the production of biogas (21.85 ml/g VS). Kinetic study was applied using modified Gompertz model, and there was well agreement between the predicted and measured values of the all pretreatments with correlation coefficient > 0.95. The pretreatment samples of rice husks and the mixing of materials improve the production of biogas and methane.

Challenging treatment of food wastes for cleaner production after the African swine fever outbreak in South Korea

Food waste is a growing global concern, necessitating effective treatment solutions. South Korea stands out with over 90% of its food waste being recycled, driven by robust resource circulation policies. Across Asia, anaerobic digestion processes are favored for food waste treatment due to their economic and environmental advantages. The South Korean Government aims to expand anaerobic digestion to ensure stable organic waste treatment. However, the 2019 outbreak of African swine fever (ASF) in pig farms led to the cessation of wet feed production, comprising 22% of total feed. This has increased the pressure on alternative recycling methods. The handling of food waste leachate, generating around 1080 t/d during treatment, has become a concern due to the discontinuation of wet feed production. The objective of this study is to develop a food waste policy. It begins by assessing food waste and leachate generation through field surveys of 346 treatment facilities engaged in pretreatment, feeding, composting, and biogasification. To mitigate the impact of ASF outbreaks in the short term, a proposed solution involves diverting food waste leachate to existing sewage treatment plant digesters during non-injection weekends and other off-peak times. This measure aims to completely treat the maximum discharge of approximately 2000 t/d during the peak summer ASF outbreak periods. For the long term, a strategy involving anaerobic digestion is suggested in response to the gradual reduction in wet or dry feed production, along with composting, the conventional treatment method. This transition not only curbs greenhouse gas emissions but also enhances biogas production, a renewable energy source. These efforts align with the Korean Green New Deal’s goal of achieving a 20% share of renewable energy by 2030.

Enhanced biogas production from rice straw through pretreatment with cellulase producing microbial consortium

Rice straw (RS) is a rich lignocellulosic biomass that can be employed for biogas generation through anaerobic digestion. However, lignin-silica encrustation around the holocellulose complex hinders its digestibility. Therefore, in this present study, RS was biologically pretreated with microbial consortium of Punjab Agricultural University (PAU decomposer), which is composed of Bacillus sp., Delftia sp., Pseudomonas sp., Lysinibacillus fusiform, Arthrobacter nicotianae, Paenibaccilus ehimensis, Aspergillus sp. and Trichoderma sp. Bio-digested slurry, the underutilized spent waste from cattle dung-based biogas plants was used as a growth medium for the mass multiplication of consortium. Soaked and chopped RS was pretreated with consortium and individual cultures in triplicate sets for 5 and 10 d and were analyzed for biochemical parameters along with cellulolytic activity. The pretreated straw was used for biogas production in 2 L capacity anaerobic digesters. Cellulolytic activities i.e., endoglucanase (0.071 IU/mL), exoglucanase (0.027 IU/mL) and β-glucosidase (3.734 IU/mL) of consortium treated RS were higher as compared to untreated RS. Biogas production from consortium pretreated RS was 187.45 L/kg RS which is 45.93% more as compared to untreated RS with 128.45 L/kg RS of biogas. This could be attributed to the synergistic cellulolytic activities of PAU decomposer leading to enhanced biogas production from RS.

Enhanced Biogas Production from Thermophilic Anaerobic Digestion of Poultry Slaughterhouse Sludge: Effect of Thermal Pretreatment and Micronutrients Supplementation

Enhanced Biogas Production from Thermophilic Anaerobic Digestion of Poultry Slaughterhouse Sludge: Effect of Thermal Pretreatment and Micronutrients Supplementation

Microbiome Diversity of Anaerobic Digesters Is Enhanced by Microaeration and Low Frequency Sound.

Biogas is produced by a consortium of bacteria and archaea. We studied how the microbiome of poultry litter digestate was affected by time and treatments that enhanced biogas production. The microbiome was analyzed at six, 23, and 42 weeks of incubation. Starting at week seven, the digesters underwent four treatments: control, microaeration with 6 mL air L-1 digestate per day, treatment with a 1000 Hz sine wave, or treatment with the sound wave and microaeration. Both microaeration and sound enhanced biogas production relative to the control, while their combination was not as effective as microaeration alone. At week six, over 80% of the microbiome of the four digesters was composed of the three phyla Actinobacteria, Proteobacteria, and Firmicutes, with less than 10% Euryarchaeota and Bacteroidetes. At week 23, the digester microbiomes were more diverse with the phyla Spirochaetes, Synergistetes, and Verrucomicrobia increasing in proportion and the abundance of Actinobacteria decreasing. At week 42, Firmicutes, Bacteroidetes, Euryarchaeota, and Actinobacteria were the most dominant phyla, comprising 27.8%, 21.4%, 17.6%, and 12.3% of the microbiome. Other than the relative proportions of Firmicutes being increased and proportions of Bacteroidetes being decreased by the treatments, no systematic shifts in the microbiomes were observed due to treatment. Rather, microbial diversity was enhanced relative to the control. Given that both air and sound treatment increased biogas production, it is likely that they improved poultry litter breakdown to promote microbial growth.

Enhancement of biogas production from sugarcane molasses-based distillery wastewater with electrocoagulation pretreatment using iron electrodes

Anaerobic digestion (AD) of distillery wastewater (DW) is not optimal because DW contains too high chemical oxygen demand (COD) concentrations. This research aimed to enhance biogas yield from DW with electrocoagulation (EC) pretreatment using iron electrodes. The novelty of this study is the combination of EC-AD for producing biogas from DW. The EC pretreatment was operated at various current densities of 39.31, 47.17, and 55.03 mA/cm2 for 8 h. Then, the supernatants were fed into the anaerobic digesters. The results showed that EC at 39.31, 47.17, and 55.03 mA/cm2 can decrease COD from 116,130 mg-O2/L to 93,976, 85,122, and 76,033 mg-O2/L. The AD with EC pretreatment at 39.31, 47.17, and 55.03 mA/cm2 resulted in biogas yields 6.8-fold, 11-fold, and 12-fold higher than the AD without pretreatment. The future research prospects are the techno-economic analysis and feasibility study of the combination of EC-AD for treating DW.

Integration of white rot mushroom cultivation to enhance biogas production from oil palm kernel pulp by solid-state digestion

Solid-state fermentation is one of the promising technologies for biogas production because of its low water footprint and solid output which is potentially used in fuel or agricultural applications. Oil palm kernel pulp (OPKP) is a by-product generated from the extraction of palm kernel oil from the mesocarp of the oil palm tree and usually contains a large amount of lignocellulose and moderate protein content, which makes it suitable for use as a mushroom substrate. Cultivation of white rot mushrooms on lignocellulose may enhance its biodegradation by biodelignification. In this study, the incorporation of the cultivation of edible white rot mushrooms, Pluerotus ostreatus and Pleurotus pulmonarius, to enhance biogas production by solid-state digestion was studied. The biological efficiency of mushroom production from the OPKP substrate of P. ostreatus and P. pulmonarius was 49.81% ± 11.28% and 46.94% ± 13.49%, respectively, corresponding to the substrate weight loss of 15.87% and 13.92%. After 30 days, methane yield obtained through the solid-state digestion of P. ostreatus- and P. pulmonarius-treated OPKP substrates was increased to 98.11 mL/gVS (191%) and 101.10 mL/gVS (197%), respectively, compared with the untreated OPKP substrate. In consideration of energy loss during the biological conversion, the calorific values of the OPKP substrate, P. ostreatus-treated OPKP substrate, and P. pulmonarius-treated OPKP substrate were 11.03 ± 0.71 kJ/g, 9.30 ± 0.23 kJ/g, and 8.83 ± 0.70 kJ/g, respectively, while those of the digestion residues of P. ostreatus and P. pulmonarius-treated OPKP substrates were 8.45 ± 0.13 kJ/g and 8.55 ± 0.11 kJ/g, respectively.