Biomethane Production Research Articles

Techno-economic ionic liquid-based capturing, electrochemical reduction, and hydrogenation of carbon dioxide in the simultaneous production of formic acid and biomethane

CO2 utilization is vital for mitigating climate change by converting CO2 into valuable products, promoting environmental protection and resource efficiency. Novel pathways for CO2 utilization to produce formic acid are proposed namely solute phase electroreduction, gas phase electroreduction, and hydrogenation, are investigated. Employing multi-objective optimization with a deep neural network surrogate model, this study identifies optimal process conditions balancing capital and operational expenditures. The result shows that CO2 hydrogenation ($868 ton−1) exhibits the lowest production cost followed by gas-phase electroreduction ($986 ton−1) and solute-phase electroreduction ($2103 ton−1). The result also shows that without any intervention at all only hydrogenation can generate profit. Furthermore, an in-depth analysis of CO2 emissions indicates that gas phase electroreduction results in the lowest CO2 emissions (0.7 kg CO2 kgHCOOH−1) among the examined pathways. Insights from our research suggest a minimum current density of 417.3 mA cm−2 is recommended to achieve at least parity with hydrogenation in terms of production cost. To push the commercialization of gas-phase electroreduction, besides current density improvement, electricity cost reduction, and carbon trading mechanism is proposed to reduce the production cost.

Enhancing the Methane Yield of Salicornia spp. via Organosolv Fractionation as Part of a Halophyte Biorefinery Concept

The present research investigated the effect of organosolv pretreatment on two species of salt-tolerant Salicornia spp. biomass, Salicornia dolichostachya and Salicornia ramosissima, for increasing biomethane production through anaerobic digestion. The final biomethane yield of de-juiced green fibers of Salicornia spp. from wet fractionation increased by 23–28% after organosolv treatment. The highest methane yield of about 300 mL-CH4/gVS was found after organosolv treatment with 60% v/v ethanol solution at 200 °C for 30 min, or at 180 °C for 30 or 60 min treatment time. Furthermore, the methane production rate increased significantly, reducing the time until 95% of the final methane yield was reached from 20 days to 6–10 days for the organosolv-treated biomass. This research shows that the process of anaerobic digestion of halophyte biomass benefits from cascade processing of Salicornia fibers in a biorefinery framework by sequential wet and organosolv fractionation for full utilization of halophytic biomass.

Biomethane and biohydrogen production from an anaerobic sludge used in the treatment of rice parboiling effluent: Specific methanogenic and hydrogenic activity

This study evaluated the biomethane and biohydrogen production capacity of an anaerobic sludge collected from a rice parboiling industry. Three main parameters were assess from an experimental batch with varying substrate-inoculum ratios (S/I): the final mass production, the maximum generation rate, and the reactors’ biomethane and biohydrogen yield. From the analysis of the final production and the maximum generation rate, the best S/I ratios found for the methanogenic and hydrogenic reactors were, respectively, 1.4 and 3.8 gCOD/gVSS. These proportions produced 102.65 mgCH4/gVSS and 27.96 mgH2/gVSS, reaching the following maximum generation rates: 32.91 mgCOD CH4/gVSS.h and 12.63 mgCOD H2/gVSS.h. In contrast to the methanogenic microorganisms of the studied sludge, the acetogenics allow the use of higher organic loads in the systems. However, the lowest S/I ratio (0.1 gCOD/gVSS) resulted in both the best biomethane and biohydrogen production yield, around 2.33 mol CH4/mol glucose and 2.46 mol H2/mol glucose. Compared to the maximum theoretical yields, whereas the sludge produced biohydrogen more effectively under high S/I ratios, biomethane was generated more efficiently in low S/I ratios. Finally, the anaerobic sludge can be employed as a satisfactory inoculum in anaerobic digestion and dark fermentation processes designed for biomethane and biohydrogen production.

The impact of salinity on biomethane production and microbial community in the anaerobic digestion of food waste components

Food waste represents a valuable resource potential for the production of advanced biofuels, including biomethane. This study systematically assessed the impact of salt on biomethane production from different components of food waste. The highest biomethane yields of 258.89 ± 10.96, 337.52 ± 16.36, and 448.49 ± 23.375 mL/g volatile solids (equivalent to biodegradability indexes of 75.75%, 88.92% and 92.66%) were achieved from cellulose-rich, starch-rich and protein-rich components, respectively, at a salt concentration of 3 g NaCl/L. The biomethane yield was improved by 9.69–31.24% with low-concentration salt compared with no salt addition, but it was inhibited by high salinity. Inhibition induced by high salinity (15 g NaCl/L) on biomethane production followed the order of protein (15.50%) < starch (28.03%) < cellulose (42.92%). Co-digestion of different components effectively mitigated the inhibitory effect of salt on biomethane production. Microbial community analysis revealed that archaea were significantly affected by high salinity. With a high concentration of salt (15 g/L), acetoclastic methanogens (Methanosatea) predominated in the digestion of starch-rich components, whilst hydrogenotrophic methanogens (Methaonmassiliicoccus and Methanobacterium) predominated in the digestion of cellulose-rich and protein-rich components. Additionally, some salt-tolerant microorganisms (SC103, Thermovirga and Methanosarcina) were selectively enriched at high salinity.

Optimization of biomethane production from lignocellulosic biomass by a developed microbial consortium

Biomethane production from lignocellulosic biomass via anaerobic digestion (AD) is a promising avenue for bioenergy. However, maximizing biomethane yield using developed microbial consortium (DMC) remains a complex challenge. This study aims to elucidate the comparative efficacy of a purposefully DMC under controlled conditions for AD of kallar grass (KG), rice husk (RH) and wheat residue (WR). The DMC encompasses Bacteroidetes, Firmicutes, Proteobacteria, Euryarchaeota, and Chloroflexi, with methanogens representing 14.6% of the community. Thorough physico-chemical characteristics and ultimate analyses provided comprehensive insights into compositions and bio-methane potentials prediction of biomasses. The digester revealed higher biomethane potentials (BMPs) with short lag phase and retention time and showed methane content of 61–64.6% during the first week of AD. The amount of volatile fatty acids (VFA) did not exceed the threshold levels, which facilitated the smooth operation of AD. The BMP was found highest in KG (289.7 mL/g VS), followed by RH (283.3 mL/g VS), and WR (269.7 mL/g VS) which is significantly higher than previously reported studies. The modified Gompertz model showed the best fit, followed by logistic and transference function models. The observed results signpost the tremendous potential of waste biomass particularly KG, RH and WR to produce biomethane by DMC. This study provides crucial insights for optimizing BMP emphasizing the promising prospects of KG, RH, and WR for sustainable bioenergy applications.

Centralized or decentralized? How to exploit Sweden’s agricultural biomethane potential

The agricultural sector holds great potential for contributing to European biomethane production, but how to best exploit it is still not clear. This study compares three technical solutions for producing liquefied biomethane from manure in Sweden: centralized biogas production and liquefaction, decentralized biogas production and centralized liquefaction, and decentralized biogas production and liquefaction. Technical and practical aspects of the three configurations are assessed through interviews with professionals, and the economic performance is compared through life cycle cost analysis. Depending on the conditions, the most cost-efficient alternative is either a gas pipeline from decentralized biogas production to a centralized liquefaction, or fully centralized production. The economic benefit of centralization increases with the number of farms involved but decreases with the biogas capacity of the system and the transport distance. The pipeline solution provides simple logistics and operation, although concession for pipe laying can be challenging. Moreover, a partly or fully centralized setup improves the delivery security of the system and reduces downtime. However, decentralized biomethane production can be an option for remote farms where centralization is not possible. For existing biogas plants, small-scale liquefaction or a pipeline to centralized liquefaction can be options for developing more biomethane production.

Incorporating saline microalgae biomass in anaerobic digester treating sewage sludge: Impact on performance and microbial populations

The aim of this study was to acclimate anaerobic prokaryotes to saline microalgae biomass. Semi-continuous experiments were conducted using two 1.5 L mesophilic reactors for 10 weeks, (hydraulic retention time of 21 days). The first reactor was solely fed with sewage sludge (control), while the second received a mixture of sewage sludge and microalgal biomass (80/20 %w/w) cultivated at 70 g·L-1 salinity. The in-reactor salinity reached after the acclimation phase was 14 g·L-1. Biomethane production was comparable between the control and acclimated reactors (205 ± 29 NmLMethane·gVolatileSolids-1). Salinity tolerance assessment of methanogenic archaea revealed that salinity causing 50% inhibition of methane production increased from 10 to 27 g·L-1 after acclimation. Microbial diversity analyses revealed notable changes in methanogenic archaea populations during co-digestion of saline microalgae biomass, particularly methylotrophic (+27%) and acetotrophic (-26%) methanogens. This study has highlighted the possibility of treating efficiently saline microalgae in co-digestion with sewage sludge in future industrial biogas plants.

Renewable gases production coupled to synthetic wastewater treatment through a microbial electrolysis cell

This study describes the use of a microbial electrolysis cells for the production of gaseous biofuels sustained by the oxidation of a synthetic wastewater. During the overall experimental investigation, the MEC’s bioanode removed on average 855 ± 57 mgCOD/d producing an average electric current of 66 ± 7 mA which was diverted into gaseous biofuels like biomethane, biohydrogen and biohythane. Three different MEC cathodic configurations were investigated selecting the electrodic materials (graphite granules GG, and mixed metal oxide MMO) and operating conditions (pH of the catholyte, additional sorption chamber). Biomethane production increased from 26 ± 4–102 ± 8 meq/d when the MMO electrode was used with respect to GG electrodic material. In contrast, the MMO electrode in combination with a CO2 sorption chamber was successfully utilized for simultaneous H2 production and CO2 sorption from a N2/CO2 mixture which simulates an anaerobic digestion biogas. The combination of H2 production and CO2 sorption allowed to obtain a gaseous mixture composed of 9% H2, 5% CO2, and 80% N2 that according to the assumption of replacing the N2/CO2 mixture with real biogas corresponded to a commercial-grade biohythane. Overall, the results highlight the potential of MECs as an efficient approach for biogas upgrading, allowing biohythane production increasing CH4 content and lowering CO2 concentration.

Production and Use of Biogas and Biomethane from Waste for Climate Neutrality and Development of Green Economy

Production and Use of Biogas and Biomethane from Waste for Climate Neutrality and Development of Green Economy

Circular Bioeconomy in the Metropolitan Area of Barcelona: Policy Recommendations to Optimize Biowaste Management

Municipal biowaste management is at the core of the transition towards a circular bioeconomy in the EU. However, most urban systems are still far from being aligned with these principles. This paper addresses the case of the Metropolitan Area of Barcelona. The current system of biowaste management is compared with a more sustainable alternative scenario. Regulatory and non-regulatory drivers and barriers for the transition from the current state to the alternative scenario are identified and later transformed into policy recommendations using a multi-stakeholder approach. This paper focuses on the separate collection of biowaste and the production of biomethane. Increasing the quantity and quality of separate biowaste collection is a prerequisite for the market-relevant production of biogas from anaerobic digestion that can be converted into biomethane. The results show that more efficient collection systems such as door-to-door or smart bins together with tax incentives such as the pay-as-you-throw principle are key to increasing the amount of collected biowaste, while targeted communication combined with controls and penalties are key to minimizing impurities. In addition to financial incentives for the construction of new anaerobic digestion plants, financial incentive systems are also required for the biomethane sector to ensure competitiveness with fossil fuels.

Bioelectrochemically enhanced biomethane production from low-rank coal using multiple microbial strains

Although microbial in-situ gasification of coal has been established to be an environmentally friendly and sustainable mining method, the low efficiency of methane production via coal micro-gasification limits the commercial applicability of this technology. In this regard, the application of electric fields can contribute to enhancing the efficiency of anaerobic microbial coal degradation. In this study, to investigate the effects of low-intensity electric fields on coal degradation by different exogenous microbial species, we conducted laboratory-scale batch anaerobic fermentation experiments at 0.9, 1.5, and 2.2 V using a micro-gas measuring device to quantify biogas production. The results revealed that application of a low-intensity electric field can promote the production of methane by different microbes, with the highest gas production (7.92 mL/g) obtained at 1.5 V, representing an increase of 131.58 % compared with fermentation conducted in the absence of an applied electric field. The electrodes facilitated the microbial utilization or dissolution of organic matter on the coal surface, leading to a reduction in surface functional groups, with the fermentation medium mainly comprising aromatic hydrocarbons. The coal particles at the anode appeared rough. Collectively, our findings in this study revealed that the application of electric fields contributed to a modification of microbial metabolism and promoted an enhancement of methane production. We believe these findings have important implications for enhancing the microbial production of biomethane from coal.

Field conditions for the synergistic increase of biomethane in the goaf of coal mines filled with corn straw

AbstractSynergistic fermentation of coal and corn straw is an effective tool to increase biomethane production. However, a large gap exists between the biomethane production conditions of corn straw filling coal mine goafs and laboratory experiments. In order to determine the effect of the field environment on synergistic biomethane production, biomethane production experiments with coal and corn straw were carried out under different conditions to find the key factors restricting the potential of biomethane production. The obtained results showed that various bacterial sources had significant influences on the biomethane production of coal and corn straw, and domesticated bacterial sources provided fermentation systems with more efficient biomethane production capacities than mine water sources. Biomethane production of coal and corn straw was relatively high under mixed conditions, but it was also promoted under unmixed conditions. Different inorganic minerals had different effects on synergistic biomethane production, which varied. For example, calcite, montmorillonite, and kaolin are common minerals in coal‐bearing strata that significantly enhance synergistic biomethane production of coal and corn straw. However, pyrite was found to significantly inhibit the synergistic biomethane production effect of coal and corn straw. Highly metamorphosed anthracite coal also presented biomethane production potential when stimulated by corn straw as a carbon source. The obtained results revealed the influences of different field conditions on the biomethane production of coal and corn straw and provided a reference for the field application of corn straw filling in coal mine goafs.

Anaerobic Co-digestion of the Liquid Fraction of Food Waste with Waste Activated Sludge

The present study investigated the feasibility of the anaerobic co-digestion (AcoD) of condensate, resulting from drying food waste, with Waste Activated Sludge in a pilot scale continuous stirred tank reactor. Different parameters were assessed in order to enhance the AcoD performance; the condensate potency (condensate A: 13 gCOD/L and condensate B: 4 gCOD/L), the volumetric ratio of condensate to WAS (0–67% v/v) and the hydraulic retention time (HRT) (20, 15 and 12 days). The results showed that increasing the condensate content in the feed from 0 to 67% v/v, enhances the organic load removal (up to 41% increased total COD removal) and the bioenergy production (up to 35% increased biomethane production). Moreover, in the case of condensate A, the reduction of HRT from 20 to 15 days enhanced the bioenergy production (up to 19% increased biomethane production) while the reduction of HRT from 20 to 12 days in the case of condensate B did not significantly affect the reactor’s performance. Overall it is concluded that condensate can be safely introduced in existing facilities for anaerobic digestion, while maintaining a more stable operation and improved effluent quality and bioenergy production in comparison with conventional anaerobic sludge digestion.Graphical

Impact of tumbling on production of biomethane from household waste.

This study utilized nine anaerobic digesters (ADs) with individual capacities of 10 l to investigate methane (CH4) gas generation from various waste combinations and operating conditions, employing both non-tumbling and tumbling processes with the aid of the Taguchi method. The experimentation encompassed different varieties of fruit waste (FW), raw vegetable waste (RVW), and mixed cooked waste (MCW) at varying proportions (1:1, 1:1.5, and 1:2) and temperatures (35 °C, 40 °C, and 45 °C), along with multiple feed inputs. Additionally, the study assessed the impact of tumbling, examining durations of 0, 10, and 20 min at a speed of 15 rpm. The results yielded substantial insights, revealing coefficient of determination (R2) values of 94.76% and 98.48% for non-tumbling and tumbling processes, respectively. Under the conditions of 40 °C and a 1:1.5 ratio, the average optimal methane (CH4) gas generation in FW without tumbling was determined to be 37.12%. For RVW and MCW at ratios of 1:1.5 and 1:2, respectively, the estimated CH4 values were 26.7% and 26.68% at a temperature of 35 °C. Comparison between tumbling and non-tumbling conditions demonstrated noteworthy improvements in CH4 gas production. For FW, tumbling for 10 and 20 min resulted in 11% and 6% increases in CH4 gas production, respectively. Tumbling also led to substantial boosts in CH4 gas production for RVW, with 31.1% and 47.9% increases after 10 and 20 min, and for MCW, with 25.7% and 12.2% increases after 10 and 20 min, respectively. Tumbling enhances CH4 gas production in anaerobic digesters, promising for waste-to-energy conversion.

Anaerobic Treatment of Food Waste with Biogas Recirculation under Psychrophilic Temperature

Food waste has emerged as a pressing concern, and thus advanced techniques to valorize food waste into nutrition rich materials as well as renewable energy are highly important. The exceptional biodegradability of food waste renders it a highly suitable substrate for anaerobic treatment. This leads to energy production and a reduction in the carbon footprint. Nevertheless, in frigid territories like Canada, the conventional mesophilic anaerobic digestion at 30–40 °C can require substantial amounts of energy. Consequently, this study introduces a new approach to treat food waste at psychrophilic temperatures (1–20 °C). Lower temperatures can negatively impact cellular processes during anaerobic treatment, rendering substrates less accessible to microscopic organisms. To address this challenge associated with lower temperatures, the study introduces an innovative biogas recirculation strategy. The primary objectives of this study are to assess the viability of anaerobic treatment for food waste at psychrophilic temperatures and to investigate the effectiveness of reintroduction of the produced biogas to the anaerobic system in enhancing biomethane generation and stability of the system. Batch experiments were conducted on food waste in various assessments, both with and without biogas recirculation. The outcomes revealed a methane concentration ranging from 68% to 93% when biogas recirculation was employed, whereas without this technique, methane concentration varied between 10% and 45%. Moreover, with biogas recirculation, the reduction in volatile solids reached a maximum of 92%, and there was an 82% decrease in chemical oxygen demand. In conclusion, the utilization of the recirculation of biogas at the psychrophilic temperature range enhanced biomethane production and reduction of volatile solids and chemical oxygen demand. This study underscores the potential of employing anaerobic treatment with reintroduction of produced biogas into the system in cold regions as an economically viable and sustainable choice for treating food waste with nominal energy consumption.

Holistic biorefinery approach for biogas and hydrogen production: Integration of anaerobic digestion with hydrothermal carbonization and steam gasification

Recently, the integration of biochemical and thermochemical processes is recognized as a promising strategy for the valorization of lignocellulosic biomass into renewable energy production. In this study, different routes for the valorization of hemp hurd for biohydrogen and biomethane production were proposed, including anaerobic digestion (AD), hydrothermal carbonization, and steam gasification. AD results revealed that NaOH pre-treatment of hemp hurd improved biomethane production yield by 164%. Comparing hydrochars from raw hemp, digestate derived hydrochars had higher mass yield due to changes in composition during AD as well as high ash content of digestates. It was found that high ash content of digestates originated from inorganic compounds in inoculum that accumulated over hemp hurd during anaerobic digestion process. Among feedstocks (hydrochars and raw hemp hurd), hemp hurd derived hydrochar at 200 °C showed the best performance in terms of H2 yield (1278 mL/g) whereas carbon efficiency reached % 92 in case of digestate derived hydrochar at 200 °C. HTC improved the steam gasification performance of hemp hurd whereas hydrochars from NaOH pretreated digestate yielded lowest hydrogen production due to the high content of inorganics, particularly phosphorus (P) and aluminum (Al). According to BMP test, spent liquor obtained at the lowest HTC temperature (200 °C) exhibited the highest BMP, reaching 213 mL CH4/g COD. Considering the overall gas products of four different routes, it is concluded that HTC as a post-treatment exhibits slightly better performance than HTC as pre-treatment. Although alkali pretreatment enhanced the anaerobic digestion performance, the resulting hydrochars exhibited low gasification activity.

Experimental analysis on the effects of trace metals as micronutrients in enhancing biomethane production

Anaerobic digestion (AD) of microbial biomass has proven to be a significant breakthrough technique in producing biogas rich in methane. The quantity of biogas obtained by anaerobic digestion processes varies significantly based on the nature and characteristics of the substrates used. This research work focuses on the use of trace metals such as Fe, Cu, Zn, Mn, Mg, Ni in proper proportions to enhance the microbial consortium thus aiding in the production of biogas of desired quality. The substrate used for this study is Food Waste and Cow dung. Food waste from the college canteen was used as the substrate and cow dung was used as an inoculum for providing a catalytic effect in the anaerobic reactor. Food waste and cow dung in the ratio 75:25 was fed into the anaerobic digesters with varying concentrations of micronutrients supplemented to the reactors operating at a pH range maintained between 6.8 and 7.2 under room temperatures (22–27 ºC). The effect of these micronutrients on the anaerobic digestion process was observed by analysing the biogas yield, pH, alkalinity, total solids, and volatile solids of the samples. Sulphates of Fe, Cu, Mn, Ni and Chlorides of Zn and Mg was used in this study. Fe, Cu, Zn, Mn, Mg, Ni were fed to the anaerobic reactor at varying concentrations to arrive at the optimum dosage for the chosen substrates. The optimum dosage for the chosen substrate concentration was taken as that concentration which yielded maximum biogas yield with less retention time. Fe at concentrations varying from 1 mg/l–5 mg/l was fed to the anaerobic reactor and the optimum dosage for the chosen substrate concentration was noted at 1 mg/l. The reactor with an Fe concentration of 1 mg/l showed an increase in biogas production rate of about 68% compared to the sample without Fe supplementation as well as the ones with other dosages greater than 1 mg/l and less than 1 mg/l of Fe dosage. Each nutrient is subjected to an individual dosage analysis before arriving at the optimum dosage and then a mixture of the arrived optimum dosages will be analysed for further study. The process set-up will be conducted for a minimum retention period of 20 days and terminated when the results show a deep fall in the biogas production for consecutive days. Biogas produced for the nutrient supplementation of 1 mg/l of Fe, 0.5 mg/l of Cu, 1 mg/l of Zn, 0.5 mg/l of Mn, 1 mg/l of Mg and 0.5 mg/l of Ni yielded a biogas of 850 ml/g VS in 10 day retention time. Triplicate samples study were conducted and biogas yield measured daily to arrive at concordant results. The results showed an increase in the biomethane yields of the substrate by about 60% compared to the reactors which had no micronutrient supplementations. Furthermore, the study summarized that not all micronutrients are essential for a successful microbial metabolism to take place in an anaerobic digester as the micronutrient Manganese at varying dosages of 0.5 mg/l, 1 mg/l and 1.5 mg/l showed an antagonistic effect on the microbial activity in the reactor. The results obtained from this study showed a significant improvement in the quantity of biogas produced from the substrates supplemented with micronutrients at optimum dosages thus arriving at an efficient and effective method for treating waste in a sustainable way.

Methane production from the biodegradation of lignite with different sizes by mixed fungi-methanogen microflora.

Biogenic coalbed methane (CBM) is a developing clean energy source. However, it is unclear how the mechanisms of bio-methane production with different sizes of coal. In this work, pulverized coal (PC) and lump coal (LC) were used for methane production by mixed fungi-methanogen microflora. The lower methane production from LC was observed. The aromatic carbon of coal was degraded slightly by 2.17% in LC, while 11.28% in PC. It is attributed to the proportion of lignin-degrading fungi, especially Penicillium, which was reached 67.57% in PC on the 7th day, higher than that of 11.38% in LC. The results suggested that the limited interaction area in LC led to microorganisms hardly utilize aromatics. It also led the accumulation of aromatic organics in the fermentation broth in PC. Increasing the reaction area of coal and facilitating the conversion of aromatic carbon are suggested means to increase methane production in situ.

Effectiveness of Water-Amine Combined Process for CO2 Extraction from Biogas

Abstract The EU countries are implementing biomethane production projects from biogas, supplying it to the natural gas distribution grid, or using it as motor fuel. It is also extremely relevant for Ukraine, supposing the problems with gas import due to Russian aggression. Biogas production from landfills, agriculture waste, and sewage is already implemented in Ukraine, so the next step must be biomethane production on an industrial scale and the selection of biogas separation technology is important. Using 11 years of industrial experience in biogas production from landfills, wide experience of the different methane-containing gases separations, and small companies’ industrial possibilities, the most applicable separation technologies for Ukraine were selected: amine, water, and combined water amine carbon dioxide separation. These technologies had compared using computer simulation with real landfill biogas flow rate debt. Results of a software simulation of the most applicable water-amine absorption technology were verified using a laboratory setup. For carbon dioxide concentration in biogas at 32–42 % vol., the specific energy consumption when using water absorption is on average 2 times less compared to amine absorption, but at the same time, the loss of methane due to its solubility in water during water absorption amounted to 7.1–7.6 %, with practically no losses in amine absorption, and minor losses at 0.17–2.8 % in combined water-amine technology. The energy consumption of combined water-amine absorption is comparable to that of water absorption due to: a) reduction of heat losses for the regeneration process of saturated amine absorbent, as part of carbon dioxide has already been removed with water technology; b) using the methane excess to compensate power consumption of the biogas compressor during the preliminary water absorption of carbon dioxide and/or to compensate heat costs of the saturated amine absorbent regeneration

Anaerobic Treatment of Dairy Wastewater: Impact of Substrate-to-Inoculum Ratio on Biomethane Production

Anaerobic Treatment of Dairy Wastewater: Impact of Substrate-to-Inoculum Ratio on Biomethane Production