Anaerobic Biogas Production Research Articles

Influence of temperature and substrate composition on anaerobic biogas production in a pilot-scale reactor

Influence of temperature and substrate composition on anaerobic biogas production in a pilot-scale reactor

An iterative comprehensive evaluation of pretreatment methods, comparative biomass analysis, and sustainability assessment for optimizing anaerobic biogas production from lignocellulosic biomass

An iterative comprehensive evaluation of pretreatment methods, comparative biomass analysis, and sustainability assessment for optimizing anaerobic biogas production from lignocellulosic biomass

Solid-State Fermentation of Trichoderma spp.: A New Way to Valorize the Agricultural Digestate and Produce Value-Added Bioproducts.

In this study, the agricultural digestate from anaerobic biogas production mixed with food wastes was used as a substrate to grow Trichoderma reesei RUT-C30 and Trichoderma atroviride Ta13 in solid-state fermentation (SSF) and produce high-value bioproducts, such as bioactive molecules to be used as ingredients for biostimulants. The Trichoderma spp. reached their maximum growth after 6 and 3 SSF days, respectively. Both Trichoderma species were able to produce cellulase, esterase, and citric and malic acids, while T. atroviride also produced gibberellins and oxylipins as shown by ultraperformance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) profiling. Experimental evaluation of germination parameters highlighted a significant promotion of tomato seed germination and root elongation induced by T. atroviride crude extracts from SSF. This study suggests an innovative sustainable use of the whole digestate mixed with agro-food waste as a valuable substrate in fungal biorefineries. Here, it has been applied to produce plant growth-promoting fungi and bioactive molecules for sustainable agriculture.

Application of Terebralia palustris shell extract for bio-coagulation treatment of produced water and digestion of generated sludge into enriched biomethane

In this study, produced water (PW) was decontaminated using the coag-flocculation method, and generated sludge after treatment (GSAT) was transformed into methane-rich gas. The origin of the active coagulant was a novel extract from the green Terebralia palustris shell (TPS). The Terebralia palustris shell extract (TPSE) was created by processing the TPS using a modified Fernadez-Kim method into a protein-based active coagulant. To increase the output of bio-methane, the GSAT and cow dung (CD) were co-digested. Anaerobic digestion process kinetics were examined. The physicochemical characterization of TPS revealed the active component, which contains 16.67% protein. The optimal dosage, pH, and settling time for the coag-flocculation process were 2 g/L, pH 2, and 20 min, respectively, which produced the best turbidity removal efficiency of 94.2%. A total of 36 mL, 490 mL, and 641 mL of biogas were recovered from the anaerobic production of biogas, respectively. With a determination coefficient of 0.9291 for the GSAT and 0.9717 for the GSAT + CD, the anaerobic digestion kinetics followed exponential and logistic models, respectively. In conclusion, coagulation and anaerobic digestion were combined to effectively decontaminate PW and convert coagulation by-products into biogas.

Improvement of gaseous bioenergy production from spent coffee grounds Co-digestion with pulp wastewater by physical/chemical pretreatments

Two steps of hydrolysis and anaerobic biogas production processes was investigated in this study. In the first step, subcritical water (SBW) hydrolysis and chemical (acid/alkali) pretreatments were carried out to enhance hydrolysis efficiency by obtaining and analyzing the total volatile fatty acids (TVFA), chemical oxygen demand (COD), and total sugar productions from spent coffee grounds (SCG) hydrolysate. The subcritical water (SBW) hydrolysis under the condition of temperature 150 °C for 30 min can greatly improve the organic matter breakdown and reached the COD concentration of 1010 g/L which was 30% higher than the untreated raw SCG. For chemical pretreatments, it was found that the alkaline hydrolysis of SCG resulted in the greatest total sugar concentration of 181 g/L whereas the operation conditions were 2.0 M NaOH at 60 °C for 1 h. The peak of TVFA concentration 3725 mg/L was found at the acid hydrolysis of SCG with 1.0 M H2SO4 acid, 60 °C for 1 h. The optimal biomethane yield of 115 mL/g COD was obtained when 1.0 M H2SO4 acid hydrolysate co-digestion with pulp wastewater which increase methane yield production 8 times of raw pulp wastewater. The pretreatment process was confirmed in this study can significant improve the converting of the biowastes to bioenergy efficiency.

Analysis Phase of Lean Six Sigma Methodology with Scaled-Down Laboratory Experiments for an Industrial-Scale Biogas Plant

Although the benefits of the Lean Six Sigma (LSS) methodology have been proven for more than 20 years, it is still underutilized in environmental science, (e.g., in anaerobic digestion and biogas production). In order to obtain a structural and data-oriented perspective for process optimization in the renewable energy sector, LSS application must be considered one of the most valuable tools. To inform this paper, the LSS analysis phase was conducted in a scaled-down environment through detailed laboratory experiments. Results showed not only the feasibility of LSS application in biogas technology, but also some useful findings such as possible root causes for low production, such as impurities, waiting time, and existing pre-treatment methods for the defined problem. The results of the experiments show that the use of old substrates can reduce the biogas production up to half of the production with fresh substrates, and that even a 10% sand content can reduce the production up to 14.2%, which shows the need for a solution to these two issues.

Biogas from poultry waste - a source of energy

The latest excessive industrial development has led to both the increase of the fossil fuel consumption and an excessive pollution. A saving solution would be considered renewable energy sources, best based on wastes, which prove energy content. The current work focuses on a case study for the biogas production, using anaerobic digestion of poultry dejections, by means of a latest generation bio-processor. These dejections are presently and normally used only as fertilizer. The experiment was performed simultaneously in 6 digesters, which were loaded daily with a quantity of material resulting from the calculated recipe, based on the characteristics of the poultry litter. Preliminary experimental analysis such as calorific value, humidity and volatile content were run. Following the results obtained, one can state that the poultry litter can be used as raw material for the anaerobic biogas production, in the future, as well.

Biogas production from wastewater: Comparing biostimulation impact of magnetised-chitosan and -titania chitosan

Industrialization and globalization have upsurged the transition from fossil fuels utilisation to renewable energy sources. Herein, harnessing magnetised nanomaterials to bioconvert wastewater anaerobically into biogas has a great potential to be an alternative green energy source. Therefore, this study engineered and explored chitosan magnetite (nCM) and chitosan-titania magnetite (nCTM) as biocatalysts for bioremediation of wastewater with methanogenic activity enhancement. The biochemical methane potential (BMP) test setups were anaerobically run for 21 days at a mesophilic temperature of 40 °C. At a high magnification of 10 kV and a micrograph scale of 5 µm, scanning electron microscopy/energy-dispersive X-ray (SEM/EDX), withimaging revealed monodisperse surface morphology of 5.0–5.3 mm. The nCTM was found to be a very potent biocatalyst with a biostimulation effect on biogas production and methanogenic activity at a 75% degree of degradation. This resulted in biogas production of 215 mL/day and 190 mL/day for the bioreactors charged with nCM and nCTM, respectively as compared with the control of 65 mL/day. The modified Gompertz model favoured the data collected kinematically. Finally, our research showed that developing nano-biocatalysts can provide viable alternatives to traditional anaerobic biogas production in wastewater treatment settings.

Maximum production point tracking method for a solar-boosted biogas energy generation system

Low biogas yield in cold climates has brought great challenges in terms of the flexibility and resilience of biogas energy systems. This paper proposes a maximum production point tracking method for a solar-boosted biogas generation system to enhance the biogas production rate in extreme climates. In the proposed method, a multi-dimensional R–C thermal circuit model is formulated to analyze the digesting thermodynamic effect of the anaerobic digester with solar energy injection, while a hydrodynamic model is formulated to express the fluid dynamic interaction between the hot-water circulation flow and solar energy injection. This comprehensive dynamic model can provide an essential basis for controlling the solar energy for digester heating to optimize anaerobic fermentation and biogas production efficiency in extreme climates. A model predictive control method is developed to accurately track the maximum biogas production rate in varying ambient climate conditions. Comparative results demonstrate that the proposed methodology can effectively control the fermentation temperature and biogas yield in extreme climates, and confirm its capability to enhance the flexibility and resilience of the solar-boosted biogas generation system.

Reactor Design for Biogas Production-A Short Review

Biogas is an alternative to gaseous biofuels and is produced by the decomposition of biomass from substances such as animal waste, sewage sludge, and industrial effluents. Biogas is composed of methane, carbon dioxide, nitrogen, hydrogen, hydrogen sulfide, and oxygen. The anaerobic production of biogas can be made cheaper by designing a high throughput reactor and operating procedures. The parameters such as substrate type, particle size, temperature, pH, carbon/nitrogen (C/N) ratio, and inoculum concentration play a major role in the design of reactors to produce biogas. Multistage systems, batch, continuous one-stage systems, and continuous two-stage systems are the types of digesters used in the industry for biogas production. A comprehensive review of reactor design for biogas production is presented in the manuscript.

Effects of Comparison of Feed Composition, pH, and Preliminary Treatment of Biogas Production from Cow Blood Waste and Molasses

Energy problems in Indonesia are issues that are not easy to solve. If the energy needs dominated by BBM continue to increase without any changes in the pattern of energy use, then Indonesia's sustainability and energy security will be disrupted. Therefore, Indonesia really needs alternative energy. Biogas is an alternative energy produced from the anaerobic degradation of organic compounds and can be a substitute for natural gas and fossil fuels. Cow's blood which is a waste from slaughterhouses can be used as a substrate for anaerobic biogas production by rumen and molasses. The objectives of this study are (i) To examine the comparison of the concentration of blood and molasses added to the volume of biogas produced, (ii) To examine the effect of pasteurization on blood on the volume of biogas produced, (iii) To examine the effect of initial system pH regulation on the volume of biogas produced, (iv) Assessing the pH setting and without adjusting the pH after measuring the volume of biogas produced. This research was conducted by making variations in the composition of feeds, pH stabilization, and blood pasteurization. The process of biogas formation is carried out for 40 days at room temperature with the response of quantitative results in the form of biogas volume every 2 days. Biogas production in cow's blood gets the best results at C/N 30, using pH 8. Pretreatment of blood pasteurization and pH stabilization also shows the best biogas results.

Enhanced Anaerobic Biogas Production From Wheat Straw by Herbal-Extraction Process Residues Supplementation.

Trace metals are essential constituents of cofactors and enzymes and that their addition to anaerobic digesters increases methane production. Many trace elements are contained in herbal-extraction process residues (HPR). The present study concerns the effect of six kinds of HPR [Danshen root (Dr), Astragalus membranaceus (Am), Isatis root (Ir), Angelica sinensis (As), and Pseudo-ginseng (Pg)] that were used as additives, respectively, in the anaerobic digestion of wheat straw on biogas and methane production. The ratios of HPR residues/wheat straw [based on total solids (TS), of wheat straw] were 3, 5, and 10%, respectively. The digesters were at 37 ± 1°C of water bath during 30 days of anaerobic digestion. The results showed that HPR had significant effects on the anaerobic co-digestion. The highest biogas productivity was achieved when treated with 10% Pseudo-ginseng residues (PGR), which yielded 337 ml/g TS of biogas and 178 ml/g TS of methane. Cumulative production of biogas and methane increased by 28 and 37% compared to the production achieved in the control. These results suggest that PGR is an effective HPR to enhance the production of methane.

Turning a waste producer into an energy producer

The paper focuses on the possibility to turn waste generated by farms into biogas, which can be used for electricity and heat generation, covering own use or even more. Three case studies, all based on experiments, are presented, the first two revealing data concerning the potential energy development from the waste, as energy carrier, the third, run on a very modern lab facility, demonstrating the high potential of the manure as renewable bio-energy source. All are based on anaerobic biogas production.

Improvement of purification technology of the liquid waste from fermentation production

One of the areas of waste disposal of fermentation industries is anaerobic fermentation and biogas production, which becomes increasingly attractive for researchers not only because of the global energy crisis but also the environmental one. Biogas production is based on methane fermentation fundamentally different from other types of fermentation, which creates certain difficulties in its implementation on a large scale. Therefore, the development of innovative energy and resource-saving technologies for the processing of liquid waste from fermentation industries is an urgent task for the development of the domestic food industry. The aim of the work is to develop, theoretically substantiate and experimentally test the technology of processing liquid waste from fermentation plants.

Anaerobic digestion of mercury phytoextraction crops with intermediary stage bio-waste polymer treatment

In laboratory experiments, Lepidium sativum L. and Mentha spicata L. were grown in compost spiked with mercury. After cultivation for 20 and 68 days, respectively, translocation factors of 0.05 ≤ TF ≤ 0.2 (Lepidium sativum) and accumulation factors of 2.2 ≤ AF ≤ 12 (Mentha spicata) were recorded. Plants were then harvested and used as feedstock for bench-scale anaerobic digesters. The reactors operated in continuously-stirred batch mode for a period of ten days. Inhibition of anaerobic biogas production was apparent with one sample set evidencing mercury-induced bacteriostatic toxicity. Otherwise, ex-situ characterization of digestate showed that the reactors were within stable operating range. A canola oil-sulphide polymer derived from bio-waste was also used as an intermediary treatment stage to test its capacity for extracting mercury from half the samples prior to anaerobic digestion, and also from the post-experimentation reactor digestate. The polymer removed mercury from digestate with a 40–50% efficacy across all samples, suggesting its potential as a sludge clean-up option. Anaerobic digestion combined with staged polymer extraction offers a potential route for the disposal of phytoremediation crops and ultimately the recovery of mercury, coincident with the production of a bioenergy vector.

Effects of Gas Supplying Patterns on Aerobic Anaerobic Biogas Production of Rice Straw

Background: Rice straw as a plant photosynthesis product, is a valuable renewable resource and it contains protein, fat, cellulose, hemicellulose, lignin and ash. It has received wide attention for biogas can solve both the energy and environment problems. Objective: To improve the degradation rate of rice straw in aerobic and anaerobic bi-phase fermentation process. Methods: Different aerobic methods were adopted to improve the degradation rate of aerobic acid producing cellulose. Results: The results showed that in different ways of gas supply test experiments the total enzyme activity of aeration mode was higher than that of the stirring air supply mode, which indicated that the aeration mode was more favorable to the growth of mixed strains of Trichoderma and Aspergillus. The gas production of TS was 438.69 mL•g-1, which was higher than both the stirring group and control group. Conclusion: The degradation utilization rate of rice straw solid organic matter can be significantly improved using method of aeration mode, and the conversion of straw biomass into biogas was promoted.

Effects of liquid digestate pretreatment on biogas production for anaerobic digestion of wheat straw

In this study, the effects of liquid digestate pretreatment of wheat straw on its biogas production efficiency and anaerobic digestion were investigated using a laboratory-scale biochemical methane potential test. Scanning electron microscope, X-ray diffraction analysis and Fourier transform infrared spectroscopy were used to analyze the changes in main compositions and physico-chemical structure of wheat straw after different pretreatment durations (3 days, 5 days, and 7 days). The results evidenced that liquid digestate pretreatment can dissolve the lignocellulosic structure, which positively promoted anaerobic biogas production. Liquid digestate pretreatment achieved a satisfactory anaerobic digestion efficiency with wheat straw as the substrate. Furthermore, the production of biogas and methane were also found to increase after pretreatment. Thus, it was concluded that a duration of 5-day liquid digestate pretreatment was optimal as it yielded 39.76% more biogas production, and 49.58% more biomethane yield, in 35.71% shorter digestion time (T80) as compared to raw wheat straw. The modified Gompertz model was able to explain the kinetic behavior during anaerobic digestion of wheat straw. Based on the aforementioned experimental observations, a comparison between effects of equivalent NH4+-N concentration of ammonia solution and liquid digestate pretreatment was conducted, which indicated that ammonolysis played crucial role in the enhancement of biogas production process by pretreated liquid digestate.

Anaerobic Biogas Production Using Microalgae Chlorella sp. as Biomass Co-digested by Cow Manure and Cow Rumen Fluid as Inoculum.

World’s demand for energy is steadily increasing following population increase, on the other hand reserves for fossil and coal energy are limited. Therefore research for renewable sources of energy is important. Biogas produced from renewable source could be one of the answer for future energy production. Researches regarding biogas production utilizing microalgae biomass such as Chlorella sp. have received much attention. In this study, co-digestion of Chlorella sp. “CD01” isolated from Cideng/Krukut River using cow rumen fluid and cow manure as inoculum were used to enhance biogas production. Our experiment used a simple non-stirred batch anaerobic bioreactor that was carried out for 29 days. Biogas volume, COD value, and microorganism were the parameters in this study. Our result showed that Chlorella sp. “CD01” and rumen fluid alone could not produce biogas. Co-digestion of Chlorella sp. “CD01” substrate and rumen fluid inoculum produced 314.5 mL biogas with yield of 43.23 mL/gTS. Co-digestion of Chlorella sp. “CD01” substrate and manure inoculum produced 1758 mL biogas with yield of 98.96 mL/gTS. The best substrate inoculum ratio (S/X) in this study was 0.33 based on cumulative biogas production. Attempts for isolating anaerobic culture from each reactor had been done using methanogenic selective media. Two methanogens isolates were morphologically characterized.

Thermal, alkali, and thermo-alkali pretreatments applied to monospecific microalgal biomass to improve anaerobic biogas production

Thermal, alkali, and thermo-alkali pretreatments applied to monospecific microalgal biomass to improve anaerobic biogas production

Effects of supplement additives on anaerobic biogas production

Anaerobic digestion (AD) converts biomass to biogas. However, its performance is often affected by the nutrient condition of AD substrate. In this study, a few substrate supplements were selected to promote the biogas production; MgO, FeCl3, and cellulase were selected based on the result from elemental analyses of the biomass. The potential impact of the additives on AD process was evaluated by performing a series of biochemical methane potential (BMP) tests. BMP reactors with the substrate with one of the selected additives (i.e., MgO of 380 mg Mg L−1, FeCl3 of 88 mg Fe L−1 or cellulase of 25 mg L−1) exhibited higher microbial activity; 5–15% more biogas production was observed, compared to the blank. Microbial community analysis showed that different additives resulted in proliferation of different microbial species. Therefore, it was decided to add the mixture of the three additives to the biomass. Addition of the mixed additive resulted in 22% more gas production.