Biogas Methane Research Articles

Hydrogen Production by Steam Reforming of Methane in Biogas Using Membrane Reactors with Dimethoxydimethylsilane-derived Silica Membranes Prepared by Chemical Vapor Deposition

Hydrogen Production by Steam Reforming of Methane in Biogas Using Membrane Reactors with Dimethoxydimethylsilane-derived Silica Membranes Prepared by Chemical Vapor Deposition

Ultrafine Magnetic Particles: A DIET-Proxy in Organic Rich Sediments?

In this work we present results of the magnetic properties characterization of sediment samples from a brownfield site that is generating methane biogas in São Paulo–Brazil. We applied interpretation procedures (frequency dependent susceptibility and time-dependent Isothermal Remanent Magnetization) appropriate to study the ultrafine magnetic fraction response of the samples. The higher content of superparamagnetic (SP) particles correlates well with the detected biogas pockets, suggesting that the methanogens activity produces these ultrafine particles, different from the magnetic particles at other depth levels. We propose the use of two simple measurement and interpretation techniques to identify such magnetic particles fingerprints. The results presented here support the use of environmental magnetism techniques to investigate biogeochemical processes of anaerobic microbial activity.

Sustained effect of zero-valent iron nanoparticles under semi-continuous anaerobic digestion of sewage sludge: Evolution of nanoparticles and microbial community dynamics.

The effects of adding zero-valent iron nanoparticles (nZVI) on the physicochemical, biological and biochemical responses of a semi-continuous anaerobic digestion of sewage sludge have been assessed. Two sets of consecutive experiments of 103 and 116days, respectively, were carried out in triplicate. nZVI were magnetically retained in the reactors, and the effect of punctual doses (from 0.27 to 4.33gL-1) over time was studied. Among the different parameters monitored, only methane content in the biogas was significantly higher when nZVI was added. However, this effect was progressively lost after the addition, and in 5-7days, the methane content returned to initial values. The increase in the oxidation state of nanoparticles seems to be related to the loss of effect over time. Higher dose (4.33gL-1) sustained positive effects for a longer time along with higher methane content, but this fact seems to be related to microbiome acclimation. Changes in microbial community structure could also play a role in the mechanisms involved in methane enhancement. In this sense, the microbial consortium analysis reported a shift in the balance among acetogenic eubacterial communities, and a marked increase in the relative abundance of members assigned to Methanothrix genus, recognized as acetoclastic species showing high affinity for acetate, which explain the rise in methane content in the biogas. This research demonstrates that biogas methane enrichment in semicontinuous anaerobic digesters can be achieved by using nZVI nanoparticles, thus increasing energy production or reducing costs of a later biogas upgrading process.

Quantification of methane emissions from UK biogas plants

The rising number of operational biogas plants in the UK brings a new emissions category to consider for methane monitoring, quantification and reduction. Minimising methane losses from biogas plants to the atmosphere is critical not only because of their contribution of methane to global warming but also with respect to the sustainability of renewable energy production. Mobile greenhouse gas surveys were conducted to detect plumes of methane emissions from the biogas plants in southern England that varied in their size, waste feed input materials and biogas utilization. Gaussian plume modelling was used to estimate total emissions of methane from ten biogas plants based on repeat passes through the plumes. Methane emission rates ranged from 0.1 to 58.7 kg CH4 hr-1, and the percentage of losses relative to the calculated production rate varied between 0.02 and 8.1%. The average emission rate was 15.9 kg CH4 hr-1, and the average loss was 3.7%. In general, methane emission rates from smaller farm biogas plants were higher than from larger food waste biogas plants. We also suggest that biogas methane emissions may account for between 0.4 and 3.8%, with an average being 1.9% of the total methane emissions in the UK excluding the sewage sludge biogas plants.

Thermodynamic and environmental study on synthetic natural gas production in power to gas approaches involving biomass gasification and anaerobic digestion

The main goal of this paper is to assess and compare three hybrid systems for the production of synthetic natural gas (biomethane) from biogas or process gas. Mathematical models were built to determine the main performance indicators and plant efficiency of the proposed solutions, such as mass and energy flows and gas composition in characteristic points of the systems, as well as the efficiencies of the full chains. The carbon footprint of the three approaches was calculated using a streamlined life cycle assessment. The results show that both methanation cases may be an interesting option for SNG production and energy storage. The energy efficiency of the solutions reaches a value of 84% for Case 1 (methanation from syngas) and 90% for Case 2 (methanation of biogas) and 3 (biogas upgrading), respectively. If the manure credit is accounted for emissions, the carbon footprint of biomethane from Case 3 is the lowest.

Stabilization of Anaerobic Co-Digestion Process via Constant the Digestate Solids Content

The process instability of anaerobic digestion (AD) is a common issue and may result in underperformance or short-term process failure. Extensive research has shown that total solids (TS) content in AD has a significant impact on system stability and performance. However, no study has examined the feasibility of stabilizing the AD process by maintaining constant TS content in the digestate. In this study, an innovative control approach based on constant TS content in the digestate during AD was developed using a mass balance equation. Two levels of TS content (desired values of 4% wet basis (w.b.) and 6% w.b.) were compared with conventional control. The process stability was examined by monitoring digestate components and pH. Substrate-specific methane yield (m3 CH4/kg VS) was used to assess the effectiveness of the controlled conditions. The results showed that the digestate TS content during AD can be controlled and that the digestion process can be stabilized by controlled conditions. In addition, constant TS in the digestate (within 1% w.b. of the desired level) gave increased levels of biogas production (10.2%), methane (13.5%), and substrate-specific methane yield (43.3%) at 4% TS, and respective increases of 16.6%, 21.2%, and 20.8% at 6% TS when compared with standard operation.

Vegetable and fruit market wastes as an appropriate source for biogas production via anaerobic digestion process

Abstract Urban waste management is a critical issue in today’s world. On the other hand, energy supply is a significant need, especially from renewable sources. In this paper, an efficient method is studied for the production of biogas from vegetable and fruit market wastes. A comprehensive study is presented on the production of methane in biogas from vegetable and fruit market wastes. For this purpose, a reactor was designed and vegetable and fruit market wastes were used as feed of the reactor for biogas production. For supplying the moisture during the gas formation, the feed was mixed with distilled water in 1:1 ratio. The mean cell residence time was set at 25 days. The results showed an intense sensitivity of the microorganism to the pH of the reactor. In acidic media, the produced biogas was very lower than neutral and slightly basic media. In addition, the percentage of the methane in the biogas showed to be increased by increasing pH from 6.3 to 7.6.

Формування математичного апарату методики протидії пожежовибухонебезпеці об’єктів захоронення побутових відходів

The fire and explosion hazard of landfills is analyzed taking into account the trends of introduction of biogas (methane) collection and utilization. According to the results of analysis and synthesis of factors of occurrence and spread of man-caused danger, available mathematical models and methods of counteraction to man-caused danger, the authors determined the initial and boundary conditions of is the basis for further development of appropriate methods of emergency response. During the analysis it was found that humidity, temperature of the landfill, the presence of sufficient oxygen at a certain point in time initiate the formation of explosive concentrations of methane in the array and contribute to the spread of hazards in landfills. The specific weight of the organic component, the value of the density of the array, the height of waste disposal affect the process of counteracting the danger, namely preventing a dangerous event and preventing the emergency from the object to the highest level of distribution, primarily in the first priority group, such as the number of victims and injured civilians and specialists of the State Emergency Service of Ukraine. A system of communication equations is determined by synthesis, taking into account the initial and boundary conditions of the mathematical apparatus, which allows to further develop a control algorithm for emergency response related to fire and explosion hazardous landfills close to settlements. Further research is aimed at: establishing the area of effective solutions for the choice of variation of solutions of individual problems to assess these indicators of the initial and boundary conditions of the mathematical apparatus in the development of emergency response methods associated with fire and explosion hazards; to develop a control algorithm for the appropriate methodology and verify its reliability.

Design and Modelling of Technologies for Upgrading and Direct Methanation of biogas: energy analysis and economic assessment

The exploitation of the biomethane as transport fuel is receiving increasing attention in many European countries. Technologies and processes for improving the Biogas-to-biomethane production with a lower energy consumption and lower costs are objective of several techno-economic studies. In this paper two promising concepts for the biogas conversion are proposed and analyzed considering both technical and economic issues. The analysis regards the biogas upgrading by means of the chemical absorption with Hot Potassium Carbonate and the direct methanation of biogas by adding renewable hydrogen. In order to assess the feasibility of these technologies the numerical modelling has been applied for the plants designing. The energy results have then been used to assess the expected biomethane production price and a sensitivity analysis on the main parameters has been performed. Finally, economic performance of the options proposed will be evaluated under different market conditions.

Improved anaerobic digestion of swine manure by simultaneous ammonia recovery using gas-permeable membranes

In feedstocks containing high ammonia (NH3) concentration, removal of the NH3 during the anaerobic digestion (AD) process can improve AD process performance. In the present study, the effect of NH3 removal using gas-permeable membrane (GPM) technology on AD process performance and biogas production was investigated using swine manure feedstock. Batch and semi-continuous AD experiments were carried out under mesophilic conditions. In the reactor with NH3 recovery, total ammonia nitrogen (TAN) concentration was reduced 28% in batch experiments and 23% on average in the semicontinuous experiment compared with the reactor without NH3 recovery. Free ammonia (FA) concentrations were also decreased by 23% and 4% on average in batch and semicontinuous experiments, respectively. These reductions in TAN and FA by GPM system positively impacted both the quality and quantity of the biogas produced by AD of swine manure. Specifically, the specific methane yield increased 9% in the batch experiment and 17% on average in the semicontinuous experiment. Furthermore, higher percentages of methane in biogas were obtained during AD retrofitted with GPM system, 24% increase in the batch experiment and 11% on average in the semicontinuous experiment (range 8.3-13.6%). Simultaneously, a uniform TAN recovery rate of 6.7 g N TAN per m2 of membrane and per day was obtained for the 205 days of semicontinuous operation; ammonia nitrogen was recovered in the form of ammonium sulphate solution. Therefore, the AD-GPM configuration produces beneficial results on biogas quantity and quality while recovering ammonia nitrogen in form of ammonium sulphate.

Direct Methanation of Biogas—Technical Challenges and Recent Progress

The direct methanation of biogas using hydrogen from electrolysis is a promising pathway for seasonal storage of renewables in the natural gas network. It offers particular advantages over the methanation of carbon dioxide separated from biogas, as it eliminates a costly and unnecessary carbon dioxide separation step. The key implementation challenges facing direct methanation of biogas are reviewed here: 1) treatment of biogas impurities; 2) competing reactor concepts for methanation; and 3) competing process concepts for final upgrading. For each of these three aspects, the state of the art is reviewed, focusing especially on results which have been validated at a high Technology Readiness Level (TRL) at recent long-duration demonstrations. The different technology solutions have advantages and disadvantages which may fit best to different technical and economic boundary conditions, which are discussed. As a final outlook, TRL 8 demo plants will be necessary to show the full potential of these systems, and to obtain consistent operation data to allow a cost comparison.

Container-Sized CO2 to Methane: Design, Construction and Catalytic Tests Using Raw Biogas to Biomethane

Direct catalytic methanation of CO2 (from CO2/CH4 biogas mixture) to produce biomethane was conducted in a pilot demonstration plant. In the demonstration project (MeGa-StoRE), a biogas desulfurization process and thermochemical methanation of biogas using hydrogen produced by water electrolysis were carried out at a fully operational biogas plant in Denmark. The main objective of this part of the project was to design and develop a reactor system for catalytic conversion of CO2 in biogas to methane and feed biomethane directly to the existing natural gas grid. A process was developed in a portable container with a 10 Nm3/h of biogas conversion capacity. A test campaign was run at a biogas plant for more than 6 months, and long-time operation revealed a stable steady-state conversion of more than 90% CO2 conversion to methane. A detailed catalytic study was performed to investigate the high activity and stability of the applied catalyst.

Вплив подрібнення соломи на інтенсивність виходу біогазу

Straw has a high energy capacity, but it is not ideal for the operation of biogas plants, since it contains a large amount of nitrogen-free substances, and only 4-6% nitrogen and mineral salts, but if it is properly pretreated, it is possible to reduce the fermentation time and increase the biogas yield. The positive results of pretreatment of biological raw materials are a high degree of grinding and homogenization of raw materials; reduction of the biomass fermentation period; the release of natural enzymes that are biological catalysts for the fermentation of biomass; stabilization of biological processes, which leads to the absence of foam and floating crust in the upper part of the bioreactor; the percentage of methane in biogas increases to 70-75 %. The aim of the study is to determine the intensity of methane fermentation of crushed buckwheat, rapeseed, soybean straw and corn stalks, depending on the size of crushed particles and the method of grinding. The article discusses the issue of determining the dynamics of biogas output depending on the method and geometric dimensions of grinding buckwheat straw, soybeans, rapeseed and corn chaff in a mesophilic mode of fermentation. The following devices were used to prepare the straw: shears, hammer mill, feed chopper and extruder. Additionally, soaking was carried out in water at a certain temperature. The prepared biomass together with the seed in a ratio of 1: 4 was put into laboratory fermenter bags and a thermostat. The biogas yield was measured for 42 days using special methods, which are patented in Ukraine. Based on the measurement results, graphs were built that characterize the dynamics of biogas output.

Stress induced by crude glycerol in a thermophilic digester: microbial community divergence and resilience, but slow process recovery.

Recovery from stress is an important property for anaerobic digestion (AD). Although AD is quite adaptable with regard to waste composition, new substrates added to stable systems may cause process decline. We tested whether crude glycerol would cause stress to a thermophilic AD microbiome previously stabilized long-term on a low C/N ratio feedstock. Three-percent (v/v) crude glycerol was added to the basal substrate (poultry litter) for two hydraulic retention time (HRT) periods. This caused stress where biogas volume and methane percentage dramatically decreased and VFA levels increased. When the basal substrate was resumed, secondary inhibition occurred, resulting in even greater stress (biogas production ceased, methane 3.6%). Unassisted recovery of system processes required eight HRT periods. In contrast, crude glycerol applied at a lower organic loading rate did not cause inhibition. Crude glycerol caused changes in dominance in the microbial community (16S rRNA pyrotags). Although process resilience was slow, the recovery of digester functions occurred in conjunction with the recovery of community structure, particularly putative syntrophic acetate-oxidizing bacteria. KEY POINTS: • Crude glycerol caused stress in thermophilic co-digestion with poultry litter. • Unassisted resilience of digester functions (methane) required 8 HRT. • Syntrophic acetate-oxidizing bacteria implicated for keystone resilience functions. Graphical abstract.

CO2 Methanation of Biogas over 20 wt% Ni-Mg-Al Catalyst: on the Effect of N2, CH4, and O2 on CO2 Conversion Rate

Biogas contains more than 40% CO2 that can be removed to produce high quality CH4. Recently, CH4 production from CO2 methanation has been reported in several studies. In this study, CO2 methanation of biogas was performed over a 20 wt% Ni-Mg-Al catalyst, and the effects of CO2 conversion rate and CH4 selectivity were investigated as a function of CH4, O2, H2O, and N2 compositions of the biogas. At a gas hourly space velocity (GHSV) of 30,000 h−1, the CO2 conversion rate was ~79.3% with a CH4 selectivity of 95%. In addition, the effects of the reaction temperature (200–450 °C), GHSV (21,000–50,000 h−1), and H2/CO2 molar ratio (3–5) on the CO2 conversion rate and CH4 selectivity over the 20 wt% Ni-Mg-Al catalyst were evaluated. The characteristics of the catalyst were analyzed using Brunauer–Emmett–Teller surface area analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The catalyst was stable for approximately 200 h at a GHSV of 30,000 h−1 and a reaction temperature of 350 °C. CO2 conversion and CH4 selectivity were maintained at 75% and 93%, respectively, and the catalyst was therefore concluded to exhibit stable activity.

Green Dairy Plant: Process Simulation and Economic Analysis of Biogas Use in Milk Drying

A project of a new milk drying unit processing 4800 kg/h of fresh milk into milk powder with expected steam consumption of 1000 kg/h (equivalent to ca. 2.6 GJ/h) was assessed. In this paper, investment profitability of this project was analyzed combining mathematical modeling, market analysis, and parametric sensitivity study. Aspen Plus was used as the simulation environment to determine values of key process variables—major streams, mass flows, and energy consumption. Co-digestion of cattle manure in an adjacent biogas plant was considered to provide biogas to partially or completely substitute natural gas as an energy source. As biogas composition from potential co-digestion was unknown, variable methane content from 45 to 60 mol.% was considered. In the next step, thorough economic analysis was conducted. Diverse effects of biogas addition depending on market prices, biogas treatment costs, and biogas methane content were simulated and evaluated. In a market situation closest to reality, biogas mixing to boiler fuel decreased simple payback period from 11.2 years to 5.1 years. However, if biogas treatment costs were high (final biogas price equal to or above 0.175 EUR/m3), the simple payback period was increased two- to sixfold, making the analyzed project practically unfeasible.

PLANT EXTRACT ADDITION FOR IMPROVED METHANE POTENTIAL OF TUBER PEEL

The percentage yield of methane in biogas ranges from 40 – 70 %, which is relatively low when compared to natural gas whose methane composition is about 90 %. Improving the methane yield will increase the efficiency of the biogas to some extent. As a result, the use of plant additives is employed to improve the methane gas yield of the biogas produced. Methane gas production from starch-rich tuber peel was investigated at laboratory scale using a batch anaerobic digester of two litres working volume at mesophilic temperature. The digesters were fed with slurry of dry tuber peel and operated for sixty (60) days. Initially, 42 % methane production was recorded. The effect of the volume (100, 300 and 500 cm3) of aqueous extracts of soya, neem and water hyacinth on methane gas yield was also studied. An increase in methane production over the control was recorded in all the digesters. Significantly higher levels of methane gas production were observed in the digesters to which 500 cm3 of aqueous extract was added with the neem extracts recording the highest.

Production of methane as bio-fuel from palm oil mill effluent using anaerobic consortium bacteria

Consortium of bacteria (Bacillus toyonensis strain BCT-71120 and Stenotrophomonas rhizophila strain e-p10) can reduce biological oxygen demand (BOD) and chemical oxygen demand (COD) values in aerobic fermentation process of POME. This study aims to degrade the organic and inorganic compounds in POME by using anaerobic bacterial consortium of Bacillus toyonensis strain BCT-71120 and Stenotrophomonas rhizophila strain e-p10 to produce biogas and reduce the values of COD, BOD and total suspended solid (TSS). Effect of fermentation time on TSS, COD, BOD and pH are investigated. Specific growth rate and generation time are determined to obtain optimal fermentation time. The results shows that the bacterial consortium of Bacillus toyonensis strain BCT-7112 and Stenotrophomonas rhizophila strain e-p10 reduced COD, BOD and TSS values of POME and produce methane in biogas for 18 d of anaerobic fermentation process. The highest reduction of COD, BOD and TSS were 86, 94 and 80%, respectively, while the highest methane content was 41.05%. The pH values ranged from 7.8 to 8.3 as sufficient condition for the bacterial growth. The highest specific growth rate of the bacteria achieved at 0.268 1/d and the lowest generation time was 3.74 d. Values of μmax and Ks were achieved 0.174 1/d and 63.011 mg/L, respectively. Value of Y = 1.4 × 109 CFU/mg, Kd = 0.42 1/d and qmax = 1.24 × 10−10 mg/CFU.d based on BOD values. Values of μmax and Ks were achieved 0.122 1/d and 5.945 mg/L, respectively. Y = 2.41 × 109 CFU/mg, Kd = 6.60 1/d and qmax = 5.062 × 10−10 mg/CFU.d. based on COD values.

Treatment of chocolate-processing industry wastewater in a low-temperature pilot-scale UASB: Reactor performance and in-situ biogas use for bioenergy recovery

The main objectives of this research were twofold: a) to evaluate the performance of a low-temperature pilot-scale upflow anaerobic sludge blanket (UASB) reactor during the treatment of a chocolate-processing industry wastewater (CIW) with high soluble chemical oxygen demand; and b) to evaluate the performance of two thermal conditioning devices (TCDs) for bioenergy recovery through the in-situ biogas use. For 275 days, the UASB reactor was operated at low temperature (17–19 °C), short hydraulic retention time (6.2 h) and variable total organic loading rate (OLRT) and soluble organic loading rate (OLRS) (10.3 ± 2.9 kg-CODΤ/m3/d and 7.9 ± 2.2 kg-CODS/m3/d, respectively). The produced biogas was burned in-situ with two TCDs, which mainly consisted of an insulated combustion chamber, a heat exchanger and a Bunsen burner. The OLRT and OLRS removal efficiencies were 59.5 ± 13.6% and 71.4 ± 13.2%, respectively, whereas the biogas production was in the range of 119–834 L/d. In-situ burning of the produced biogas with the TCDs increased the influent temperature between 0.8 and 5.8 °C, which improved the biogas production of the UASB reactor. The CIW energetic potential was calculated based on the UASB reactor operational parameters, the calorific value of methane in biogas and the daily CIW production (90 m3) of the studied factory. The estimated CIW energetic potential (13.59 MJ/m3CIW) represents a sustainable source of energy, which could be enough to satisfy the power consumption of 25–42 households in Toluca Valley Metropolitan Area, Mexico.

Analysis of residual gases of internal combustion engines at working on biogas and their effects on the environment

Given the limited resources of Ukraine in petroleum fuels for internal combustion engines, the use of alternative fuels is quite relevant. One of their sources is biogas from livestock by-products and garbage dump. Ukraine has significant volumes of these renewable sources, the potential of which reaches more than 100 million tons of conventional fuel. Unfortunately, this resource is rarely used. In developed countries, biogas is widely used for electricity generation in power plants with internal combustion engines. Today in the United States the volume of biogas production is about 500 million m3 / year, in France – 40 million m3 / year. In the Czech Republic, Austria, Denmark, Finland and other countries, biogas is used as a motor fuel. Business Concerns Volvo, Scania produce buses running on biogas. In Ukraine, gas from landfills and livestock by-products is mostly released into the atmosphere or burned by flares, polluting the surrounding air. This causes additional greenhouse gas emissions. It is known that the main source of air pollution is vehicles. Exhaust, i.e. residual gases are considered toxic. The World Motor Vehicle Park annually emits up to 260 million tons of carbon monoxide, 40 million tons of volatile hydrocarbons, nitrogen oxides and others. The composition of the residual gases of the internal combustion en-gine depends on the component composition of the sources of fuel and, of course, on the mode of operation of the internal combustion engine In the given article the structure of residual gases of internal combustion engines at work on biogas is analyzed and their influence on environment is generalized. Based on analytical calculations, it is determined how the amount of residual gas components changes depending on the excess air ratio and the per-centage of methane in biogas. Recommendations for improving the performance of internal combustion engines on biogas by using it in mixtures with natural gas are given. According to the research results, the corresponding graphical dependences are constructed.