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Morocco is located in the northwestern part of Africa and is one of the Mediterranean countries threatened by the increasing generation of organic waste. Without any treatment or management strategy, these wastes are dumped illegally in large quantities and can affect natural resources. Recently, the anaerobic digestion method seems to be one of the best processes available to treat organic wastes. In the present study, the 15-m3 Puxin digester was used to produce biogas and digestate from cow dung. A total amount of 3500 kg of cattle dung was treated, generating a specific biogas production of 0.163 m3 kg−1 volatile solid. Furthermore, the application of the digestate diluted to 50% as biofertilizer for maize crop showed higher yield (P < 0.05) compared to the NPK fertilizer (45 quintals per ha and 33 quintals per ha respectively, i.e., + 36%) and the control (+ 80%). These valuable results can promote the development of biogas technology in Morocco as well as in similar countries. [ABSTRACT FROM AUTHOR]

Biogas is one of the renewable energy sources that may be used as an alternative. It can reduce negative environmental effects by producing electricity from agricultural waste and industrial effluents. This study intends to construct a lab-scale version of the VMMI instrument, which monitors the methane quality inside and outside the laboratory. In addition, this study aims to investigate the biogas upgradation by CO2 capture at atmospheric conditions utilizing three different alkaline absorbents (NaOH, Na2CO3, KOH) in the volumetric meter. To assess the efficiency of these alkaline solutions, an artificial biogas composition with a varied ratio of CO2 from 1 to 95% was prepared using natural gas as a methane source and CO2-filled cylinder. The biogas composition was analyzed on a gas chromatograph before and after CO2 absorption in an alkaline solution. In this study, potassium hydroxide had the maximum CO2 removal, 98%, compared to NaOH and Na2CO3. To further assess the effect of an acidic solvent, 1 M HCl acid was used, but it had a very low CO2 absorbing efficiency of 1.8%. Hence, major findings can help better understand proper alkaline solvent selection that contributes to high CO2 capture efficiency, easy use, and low cost. [ABSTRACT FROM AUTHOR]

Phytochemicals are potent inhibitors of in vivo ruminal microbial activity and methanogenesis of plant materials. However, a knowledge gap exists on the influence of phytochemicals on microbial ecology and biomethane production under anaerobic bioreactor environment. In this study, high-throughput metagenomic sequencing and physicochemical analyses were used to evaluate the effects of phytochemicals on the microbial community structure and methane production efficiency of different avocado oil processing wastes under standard batch anaerobic digestion (AD) over the 30-day period. Results showed that the avocado wastes produced methane yields (MY) ranging from 79 to 247 mL CH4/gVSadded, with skin/peels (AS), cold-pressed pomace (CDP), cold-pressed wastewater (CDW), and hot-pressed pomace (HDP) digestates showing diauxic methane production patterns and peak daily methane production at day 7. Avocado seed (AK) digestate, characterized by high phytochemical content, exhibited a monophasic methane production pattern and the lowest MY. Pseudomonas, Romboutsia, Paeniclostridium, and Methanocorpusculum, Methanosaeta, Methanoregula, and Methanosarcina were the dominant bacterial and archaeal genera in all digesters. Lipolytic Pseudomonas were enriched in the early AD phase (0–15 days), whereas Romboutsia, Paeniclostridium, and Clostridium increased in the late AD stage (days 13–30). Spearman correlation analyses showed that the total polyphenols and saponins exhibited a significant negative influence on biomethane production. Alkaloid level significantly affected Romboutsia, Paeniclostridium, and Methanoregula, while saponins negatively correlated to AC160630, Clostridium, Methanocorpusculum, and Methanoregula. To the best of our knowledge, this is the first report on the potential negative impact of phytochemicals on the microbial community structure and biomethane production from avocado processing wastes. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the feasibility of producing biogas by combining solid poultry slaughterhouse wastes (SPSWs) with fruit and vegetable solid wastes (FVSWs) and to obtain the optimum conditions for maximum biogas production by means of anaerobic digestion (AD). The ratio of available carbon to available nitrogen (C/N), as a critical parameter in producing methane, was adjusted by mixing the appropriate amount of SPSWs with FVSWs. For each load, a 50-L pilot-scale digester was operated for 40 days. For start-up and seeding, the biogas reactor was bioaugmented using the anaerobic sludge of an industrial poultry wastewater treatment plant. The analyzed SPSW, which had a C/N ratio of 5.75, was combined with FVSWs to obtain C/N ratios of 20, 30, and 40. Furthermore, it was found that the highest biogas yield occurred when the C/N ratio of the feed was 30. Also, for all three loading ratios, biogas production volumes were 215.1, 241, and 182.7 L, respectively, where methane's shares were 104.5, 120.6, and 91.7 L of the total gas volume that constituted 48.6, 50, and 50.2% of the produced biogas. Therefore, the obtained results from the process of mesophilic AD of this type of solid wastes illustrate that it is possible to efficiently produce biogas as a renewable energy source by combining SPSWs and FVSWs, instead of burning or burying them. [ABSTRACT FROM AUTHOR]

The modern world's major challenges, such as global warming, air pollution, and increasing energy demands, escalate the importance of sustainable development and transition toward renewables using innovative and environmentally friendly solutions, such as intensifying chemical processes, to reduce carbon footprints effectively. Aiming to enhance the process toward negative carbon emissions, this perspective explores the intensified membrane reactors for reducing the energy intensity of converting biogas into methanol, a versatile chemical feedstock, and renewable liquid fuel. Syngas and methanol synthesis processes, catalysts, and membranes were explored, and novel reactor designs were proposed. Introduction of selective membranes into the catalytic reaction zone to combine synthesis separation steps could enhance the system efficiency and intensify the process by recycling energy and materials, besides reducing costs and required energy for the separation process: the continuous harnessing of products shifts reactions toward desired species while recycling energy and materials enhances the process efficiency, and separating water from methanol reduces the required energy and costs of extra processes for methanol separation. The successful implementation of this technology holds significant promise for sustainable developments in producing chemicals and renewable fuel from renewable biogas and reducing methane and carbon dioxide emissions toward achieving carbon‐negative technologies. [ABSTRACT FROM AUTHOR]

Different technologies can be utilised to mitigate environmentally harmful ammonia (NH 3) emissions after field application of liquid animal manure (slurry). After a solid-liquid separation, air-plasma technology can acidify the liquid fraction and enrich its nutrient value by increasing the amount of inorganic nitrogen. The present work investigates the emissions of NH 3 and volatile organic compounds (VOC) after field application of the following fractions of pig slurry and slurry digestate: i) untreated slurry (UN), ii) liquid fraction of slurry (LF), iii) liquid fraction of slurry treated with air from the plasma treatment (LP). Emissions were measured with a system of wind tunnels and a cavity ring-down spectrometer for NH 3 concentration measurements and a proton-transfer-reaction mass-spectrometer for measurements of VOC. For both slurry types, the cumulative NH 3 emissions were in the following order UN > LF > LP. All the differences were significant (P < 0.05), except between pig slurry LF and LP. The reduction in cumulative NH 3 emission obtained by the treatments compared to UN were 55–74% and 70–89% for LF and LP, respectively. The slurry separation decreased dry matter by 46–54% and resulted in a rapid decrease in slurry exposed surface area after application, presumably due to high infiltration. Several VOCs were measured after application of the slurry, but continuous emission was undetectable for all VOCs. The very low VOC emission was presumably due to high infiltration of the low dry matter slurry treatments and low concentration of VOC in the digestate. Science4Impact Statement • Separation with decanter centrifuge reduced slurry DM by 46–54%. • Treatment with plasma treated air lowered slurry pH by 1.6–1.8 units. • Separation of slurry decreased cumulative NH 3 emissions by 55–74%. • Separation + treatment with plasma treated air reduced NH 3 emission by 70–89%. • All slurry types investigated had low VOC fluxes after application. [ABSTRACT FROM AUTHOR]

Digestate is a product with valuable fertilizing properties, remaining after the anaerobic fermentation process. An essential feature of the substance in question is its high water content of up to 97%. To improve the fertilizer value of the digestate, it is necessary to dehydrate it to produce a concentrated product. This paper determined the possibility of dewatering the digestate using an innovative reactor design. The study, conducted on a laboratory scale, used digestate from a Polish biogas plant. The dewatering technique described in the paper is based on the evaporation and condensation of water vapor on the inner surface of the reactor dome. The condensate accumulated on the leach trough and was directed to a storage tank. During the weeks of testing, 11.5 kg of condensate was separated from the initial weight of the digestate (32 kg), with a dry weight of 6.11%. The resulting condensate from dehydration had an average pH value of 9.0 and an average ammonium nitrogen content of 2.07 g∙kg−1. The economic calculations made in the paper allowed for estimating the expected savings associated with the management of digestate in Poland. The research showed the proposed technology's high potential for dewatering digestate under laboratory conditions. [ABSTRACT FROM AUTHOR]

Using biogas fuel in a modern internal combustion engine equipped with gas equipment of the fourth and fifth generations can create several difficulties. This is due to the low heat of combustion of untreated biogas, the presence of moisture, and the specifics of the injectors. The main problem of the studies we considered is that there are no data on the operating parameters of biogas fuel injectors. Studies on the parameters of the Matrix, Barracuda, Valtek, Hana, and Keihin injectors in relation to biogas fuel were carried out according to performance indicators, the linearity of operation, the resistance of the injectors, the ability to maintain factory parameters, and service life. According to the indicators of performance and linearity of work, Valtek injectors have the highest deviation in productivity and linearity of work, with an average of 38.8%, and the lowest deviation of Barracuda injectors is 7.5%. Keihin (15.3%) and Hana injectors (19.1%) also showed good performance indicators, and therefore can be used effectively for biogas fuel systems. As a result of research on the response time of the injectors, it was established that the best indicators were found for Hana (1.75 ms) and Keihin (1.99 ms) injectors. Valtek injectors showed good response rates (2.07 ms), as did Barracuda injectors (2.19 ms), but the highest response time was found in Matrix injectors, with 2.44 ms. Keihin injectors had the lowest average resistance value of 1.25 ohms, and Valtek injectors had the highest resistance value of 3 ohms. According to the research results, Keihin, Matrix, and Barracuda injectors provide the best ability to maintain factory performance when using biogas fuel at 2 to 5%, and Valtek had the worst performance up to 20%. Keihin, Barracuda, and Hana experimental injectors had the highest service life, which is from 200 to 250 thousand km of car mileage. The lowest indicators were found for Valtek and Matrix injectors, the service life of which varies from 70 to 100 thousand km of mileage. [ABSTRACT FROM AUTHOR]

This numerical study investigates the impact of the reaction temperature, molar ratio of CH4:CO2, and catalyst porosity (εp) on the H2 yield and H2 selectivity during biogas dry reforming over a Ni/Cr catalyst. Using COMSOL Multiphysics, we conducted detailed simulations to elucidate the underlying reaction characteristics. Our findings reveal that increasing εp from 0.1 to 0.95 significantly provides a 5 times increase in H2 production and a 2.3% increase in H2 selectivity while simultaneously reducing CO selectivity by 2.3%. This effect is attributed to the improved mass transfer within the catalyst bed, leading to more efficient reactant conversion and product formation. Additionally, we observed a strong correlation between higher reaction temperatures and increased H2 yield and H2 selectivity. By optimizing these operational parameters, our results suggest that Ni/Cr catalysts can be effectively employed for the sustainable production of H2 from biogas. [ABSTRACT FROM AUTHOR]

The fate of biobased and biodegradable cellulose-derived plastics in landfills represents an important topic from economic and environmental points of view. Anaerobic digestion is a cost-effective waste-to-energy technology. The behaviour of six polymer types—that is, cellulose (C), cellulose acetate (CA), viscose (V), nanocellulose (NC), acetate textile (AT), and heteropolysaccharide pectin (P)—was studied under anaerobic batch mesophilic conditions in a landfill leachate for 147 days. The cumulative biogas production was as follows: C>V=CA>>AT>>NC=P. Metagenomic analysis revealed notable variations in the proportion of bacterial and archaeal domains with the highest archaeal abundance in the presence of CA (80.2%) and C (78.5%). At the end of digestion, cellulolytic, hydrolytic, and dehydrogenase activities were measured in the intact samples, as well as the liquid and solid fractions, under aerobic and anaerobic conditions. Cellulolytic activity in P was detected only in the pellet, while in NC, activity was mostly in the supernatant under both aerobic and anaerobic conditions. Scanning electron microscopy and confocal scanning laser microscopy showed a defragmentation and degradation of polymeric substrates as well as microbial colonisation. Based on the results, landfill leachate is appropriate for the anaerobic biodegradation of cellulose-derived polymers; however, the process is polymer specific. [ABSTRACT FROM AUTHOR]

This research explores the potential for generating biogas and clean energy by processing organic waste, a process that can become a sustainable solution to Syria's energy needs. Focusing on agricultural residues generated from citrus fruit orange, date, and jujube cultivation in Syria, this study evaluates the potential for anaerobic digestion of these residues for biogas production. It highlights the influence of substrate composition and the optimization of fermentation processes on biogas and methane production. The study focuses on evaluating the anaerobic digestion process by examining various dosages ranging from 20% to 50% dry matter for citrus orange waste, and different types of substrate with a fixed ratio of 20% substrate dry matter. It specifically discusses the factors influencing the inhibitory effect of anaerobic digestion, giving particular consideration to orange waste, a significant byproduct of the citrus industry. The biogas produced maintained a stable methane content when a citrus‐to‐inoculum ratio of 30:70 was used. Jujube waste, characterized by a composition rich in cellulose and hemicellulose, exhibited a higher potential for biogas and methane generation among the fruit waste investigated, particularly when combined with the inoculum in a 20:80 ratio. The research findings underscore the potential of using Syrian agricultural residues, including orange citrus peel, date, and jujube fruit, for the production of biogas through anaerobic digestion. [ABSTRACT FROM AUTHOR]

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Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the context of climate policy, measures are being taken around the world to reduce pollution. These have been intensified in the areas of transport, industry, and energy, with the goal of zero emissions. The role of the biogas plant in energy transition and as a waste treatment plant for disposal is very important. This article describes research on a dynamic anaerobic digestion (AD) process plant. The subject of this study was leather shavings, which is a problematic waste. The research presented here is intended to demonstrate the decomposition of the flesh in the process, to confirm its biogas yield, and to evaluate the biological and technical parameters of the process. High biochemical stability was achieved for each of the tests evaluated, and no specific technical requirements were demonstrated. The only technical aspect to be addressed during operation was sedimentation, which can be solved by preparing the mixture earlier or by changing the mixing method. This made it reasonable to investigate the material further in the context of an industrial project. The characteristics of protein degradation in the AD process resulted in a high methane content in the biogas, above 65%. It was also observed that the long conditioning time of biogas in the gas cushion favourably affected the proportion of methane in biogas. Analytical results confirmed 77.5% methane content, which was a very good result. This paper presents the results of a surprising effect of chromium, primarily Cr (III), on the performance of anaerobic digestion. [ABSTRACT FROM AUTHOR]

Energy is a crucial element in the industrialization and socio-economic development process of any nation. While in developing economies, proactive measures are taken towards making for energy adequacy, the need to develop an alternative source of energy cannot be over-emphasized. This project suggests a way forward in exploiting and developing biogas from different substrates for rural communities. Biogas technology from animal dung is feasible for smallholders with livestock producing 5kg manure per day, an equivalent of 4 pigs or 2 cows. The size of the digester was focused on achieving the desired output which is the biogas itself using anaerobic digestion and the substrates used were cow dung, pig dung, and poultry droppings. This fabrication was made to show a simple demonstration of biogas production by decomposition of cow dung, pig dung, and poultry dropping. Three digesters were made from plastic tanks of 9-liter capacity. The digester was connected to the water displacement setup for the gas collection. Each substrate had two (2) replicas, so as to get average and more accurate results, making a total of nine (9) fabricated digesters. The water displacement method of gas collection was adopted. The mode of feeding used was batch feeding (discontinued feeding). From the comparisons, it was evaluated that 5kg of Poultry droppings produced approximately 0.0133 liters of biogas per day. An adult pig, which produces about 5kg of manure daily (out of which is 90% water, a 7% volatile solid), produces an average of 0.2301 liters of biogas daily, and 5 kg of Cow dung produces about 0.0052 liters of biogas - all under 30 days retention time, and same environmental conditions. [ABSTRACT FROM AUTHOR]

The energy crisis associated with energy poverty in Africa continues to keep millions of men, women and children in absolute poverty due to inadequate access to clean energy. Despite its widely recognised importance for sustainable development, theoretical and policy discourses have largely remained dormant with respect to the role that the paradox of energy deficiency plays in the underdevelopment of Africa. This study illustrates how the exploitation of energy potential can be tailored to exert a positive impact on household livelihoods and sustainable development in Africa. Specifically, this study was aimed at determining the impact of biogas technology on the livelihood of beneficiaries and estimating the environmental benefits of biogas technology in terms of global warming potential in order to provide policy recommendations. The results show that the beneficiaries' livelihood assets, including the human, physical, financial and social capital, were positively impacted by the use of biogas technology. The dominant impact of biogas technology was financial, as the beneficiaries witnessed a significant increase in their household incomes. This was possible through the reduction of the expenditure on fuelwood and the sale of digestate. The environmental benefits of disseminating biogas technology as a cleaner energy source were significant, providing evidence that mobilising the biogas potential in Africa would lead to significant decarbonisation of household energy supply. This shows that integrating the livelihood enhancement components in energy interventions amid the enormous unexploited energy potential would contribute to the sustainable transformation of the African continent. In resonance with Agenda 2030, we conclude by contributing to repositioning energy availability, affordability, and reliability as critical components of an energy revolution for sustainable development in Africa. [ABSTRACT FROM AUTHOR]

The recovery of energy potential through anaerobic digestion is a widely used method for treating biodegradable waste. However, challenges related to operational issues, waste characterization, and process instability hinder its widespread application and result in low methane yields. This review aims to organize and analyze the static and dynamic parameters that influence biogas yield in order to optimize its production. Biogas typically consists of 50–70% methane (CH4) and 30–50% carbon dioxide (CO2) along with traces of other gases. The paper highlights various solutions to enhance CH4 production, including substrate pre-treatment, co-digestion, Fe0 powder addition, anaerobic fungi, multi-stage biodigester design, and controlling factors influencing anaerobic digestion. These factors primarily include methanogenic potential, C/N ratio, digestion temperature, pH, reactor tightness, and Pressure. However, the use of bioreactors faces technical, socio-economic, and environmental constraints that vary between developed and less developed countries, as discussed in the paper. Through an analysis of over 30 substrate types, the optimum ratios for certain substrates to achieve higher biogas yields were identified. For cow manure mixed with other materials, the yield increases within a C/N ratio of 20–30 and decreases at a ratio of 35. In the case of poultry droppings mixed with other substrates, the yield increases within a C/N ratio of 18–22. Food waste yield, on the other hand, varies significantly due to the differing characteristics of food waste sources. In summary, this study emphasizes the importance of optimizing biogas production through understanding and controlling the influencing factors. It provides insights into potential solutions and optimum substrate ratios for improved biogas yield. [ABSTRACT FROM AUTHOR]

Biogas desulphurisation plants aim to remove hydrogen sulphide and other gaseous compounds that occur in the gas mixture. This mainly concerns the reduction of H2S which reacts with most metals such as iron or copper, which leads to the corrosion of pipelines and equipment. The aim of this research was to use two materials to adsorb hydrogen sulphide from biogas and to compare the efficiency of these two processes. Biogas was passed through both adsorbents. The concentration of hydrogen sulphide was measured upstream and downstream of the adsorbent bed. The results are summarised in diagrams. The first material used in the biogas desulphurisation plant at the wastewater treatment plant was bog iron ore. The bed was replaced several times during the year to maintain the efficiency of hydrogen sulphide removal from the biogas. After a year, a new adsorbent called "SulfurE" was used in place of the bog iron ore. The new bed operated with higher efficiency than the bog iron ore. The operating period between bed replacements was also extended. The bog iron ore bed in the desulphurisation plant was replaced on average 3 to 4 times a year, depending on the amount of hydrogen sulphide flowing into the desulphurisation plant (the more H2S, the higher the frequency of bed replacement). The bed in the desulphurisation plant filled with the "SulfurE" product operated for about 9 months with 90% hydrogen sulphide absorption efficiency (depending on the quality of biogas produced). [ABSTRACT FROM AUTHOR]

In recent years, Poland has seen a rapid increase in installed capacity in the renewable energy sources (RES) sector. This increase mainly concerns weather-dependent sources such as PV and wind installations, whose intermittent operation destabilizes the Polish power system (PPS). The solution to fluctuations in PPS operating parameters are stable and controllable RES sources, among which demand-driven biogas plants (with an energy storage in the form of biogas) have a special development potential. The aim of this paper was to describe the construction and principles of operation of peak biogas plants and to analyze the possibilities of including them in the operation of PPS. The paper shows the fundamental differences between the operation of typical biogas plants (producing electricity and heat continuously) and demand-driven biogas plants, in which biogas production takes place continuously, while electricity production occurs periodically, during the highest demand for power during the day. It was found that demand-driven biogas plants are a promising alternative to the previously used coal-fired units, battery energy storage units and pumped-storage power plants and in the future they may act as a stabilizer of the National Power System, achieving available electrical power of up to 11.1 GW. [ABSTRACT FROM AUTHOR]

Due to the carbon dioxide (CO2) content in biogas, using biogas is relatively limited in many industrial applications. Hydrogen (H2) is a highly reactive gas that is used extensively to enhance the burning rate of biogas, on the other hand, nitrous oxide (N2O) is a powerful oxidizer that can improve the burning rate of biogas. The laminar burning velocities of biogas-hydrogen-air and biogas-N2O mixtures at various equivalence ratios were investigated experimentally using the spherical flame methodology. It was found that the laminar burning velocities were enhanced in biogas-hydrogen-air and biogas-N2O mixtures. However, the enhanced laminar burning velocities of biogas-N2O showed a more significant increase than biogas-hydrogen-air due to the significant energy released by the N2O decomposition reaction. The flame thickness of the biogas-N2O mixture indicated lower values than biogas-hydrogen-air mixtures, suggesting a higher flame instability of the biogas-N2O mixture than biogas-hydrogen-air mixtures. The Lewis number of biogas-N2O mixture showed lower values than all biogas-hydrogen mixtures, indicating higher diffusive-thermal instability influence on biogas' flame. The reactions of H + O2⇔ OH + O and H + CH3(+M) ⇔ CH4(+M) represented the most significant reactions influencing the laminar burning velocities of biogas-hydrogen mixtures, while the N2O + H⇔N2 + OH, and N2O(+M) ⇔ N2 + O(+M) reactions represented the most important reactions in biogas-N2O combustion. [ABSTRACT FROM AUTHOR]

The increasing volume of textile waste in landfills and incineration poses severe environmental challenges. Waste valorisation of textile waste via anaerobic digestion (AD) is preferable, as it offers economic and environmental benefits, but it is hindered by textile complexity, necessitating effective pretreatment technologies to improve biogas production. This study aims to evaluate various pretreatment technologies for biogas production from textile fibres via AD. A weighted‐scoring analysis (WSA) assessed pretreatment methods based on technical, economic, environmental and operational criteria. Hydrothermal pretreatment emerged as the most technically effective method, scoring 140 owing to its substantial methane enhancement. Economically, shredding was the most viable option, scoring 125, as a consequence of low capital and O&M cost. Environmentally, hydrothermal and deep eutectic solvent (DES) pretreatments were top performers with 100 points owing to low environmental impact and positive heat reactions. In a case study conducted in the Auckland region, the potential environmental impact (PEI) obtained from hydrothermal and DES were 169 and 92 per year, respectively, resulting in minimal environmental impact. Operationally, ultrasonic and biological pretreatments scored highest owing to their ease of operation, and minimal health and safety requirements. Overall, hydrothermal pretreatment achieved the highest WSA score of 340, reflecting its balanced performance across all criteria. Hydrothermal pretreatment is the most promising technology for enhancing biogas production from textile waste. Its technical efficiency, economic feasibility and environmental benefits regarding the WSA score make it suitable for upscaling and providing a viable solution for managing textile waste in the AD plant. © 2024 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Biogas, one of potential renewable energies, could play an effective role in fulfilling the world's energy demand. The presence of elevated concentrations of H2S in biogas is problematic because of its highly corrosiveness and toxicity. Recently, there has been interest in utilizing biochar as alternative adsorbent to remove H2S from biogas. In this study, the adsorption capacity of banana peel biochar (BPB) and banana empty fruit bunch biochar (BEFBB) wastes for removing H2S from biogas was investigated. Biochar was produced through the pyrolysis process. Firstly, physical and chemical properties of biochar (moisture content, volatile compound content, ash content, fixed carbon, iodine number, pH, and BET surface) were determined. BEFBB possessed higher fixed carbon content (38.05%), iodine number (146.98 ± 2.29 mg g−1), pH value (8.7 ± 0.3), and larger BET surface (3.18 m2 g−1) than BPB. Secondly, the effect of biochar types and biochar pellet sizes on the adsorption capacity was investigated. The adsorption experiment was carried out, using anaerobically digested biogas, in a packed column containing 10 g of biochar with the pallet size of 1.0 cm of diameter, the initial H2S concentration of 500 ppm at the flowrate of 500 mL min−1. Adsorption efficiency curves showed that the two types of biochar presented high removal capacity for H2S but very low removal capacity for CH4 and CO2. The breakthrough adsorption capacity of BPB and BEFBB was found to be 5.85 mg g−1 and 7.65 mg g−1, respectively, consisting well with their physiochemical characterizations. Then, the effect of biochar pellet sizes on the removal efficiency was studied at three different pallet sizes (0.50 cm, 1.00 cm, and 1.50 cm of diameter). Smaller pellet size adsorbent showed higher removal efficiency than larger pellet size owning to its larger surface area. The FTIR analysis result of BEFBB shown that carboxylic and hydroxide radical groups were most likely responsible for H2S adsorption. Finally, the SEM/EDX results showed significant changes in morphological and chemical properties after the adsorption process. Therefore, BPB and BEFBB could be used as an alternative adsorbent for removing H2S from biogas. [ABSTRACT FROM AUTHOR]

The anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) has shown to be a viable alternative since it allows energy recovery in the form of methane and generates a residue (digestate) that can be applied effectively as a soil improver or fertiliser. The potential for methane production and the digestates' characteristics depend on the substrate characteristics and the process variables such as temperature, solids retention time, and organic load. This study dealt with OFMSW anaerobic digestion under different organic loading rates and temperatures and the characteristics of the resulting digestates. Three semi-continuous reactors were operated at 20, 35, and 55°C and fed daily with ground, fresh OFMSW from Mexico City. The inoculum was temperature-adapted UASB granular sludge. The main results indicate that the anaerobic digestion was adequate, as the pH values were slightly alkaline, which is sufficient for methanization, and the alkalinity was not a limiting factor. Potassium and PO4-P increased with the organic load, and Kjeldahl nitrogen decreased. At 20°C, total organic carbon (TOC) increased substantially with the organic load; at 35°C, it remained without significant changes; and at 55°C, TOC slightly decreased with the organic load. The C/N ratio changed accordingly to TOC variations. At 20°C, the residual biogas potential increased with the organic load; at 35 and 55°C, it decreased with increasing organic load; the residual biogas potential increased with residual fatty acids concentrations. To comply with international standards for agricultural use, the digestates need only dewatering and supplementing with PO4-P. [ABSTRACT FROM AUTHOR]

The widespread nature of citrus cultivation, processing, and consumption on a global scale results in a substantial volume of by-products within the citrus processing industries. The indiscriminate disposal of these by-products, without a proper treatment and disposal methods, poses a significant environmental hazard. Amongst, citrus peel waste being a prolific by-product, is generated on a large scale and is increasingly gaining recognition for its industrial potential in producing fuels and chemicals. This encompasses biofuels such as ethanol and biogas, bioactive compounds like flavonoids, alkaloids, essential oils, D-limonene, and pectin, as well as various biochemical compounds including organic acid, biosurfactants, enzymes, and bioplastics through strategic valorization processes. The valorization process entails a variety of techniques, including chemical, biological, and physical treatment methods. Physical treatments, such as microwave and ultrasound-assisted extraction methods, are employed, alongside extraction using solvents and biological methods including fermentation and saccharification, which are integral components of the valorization process. Each of these methodologies contributes to the production of the aforementioned value-added compounds. Furthermore, the recently developed supercritical fluid can also be employed for extracting these valuable compounds, enhancing the versatility and efficiency of the valorization process. This review addresses a refinery strategy, emphasizing the incorporation of a suitable valorization/treatment approach to transform citrus peel waste into high-value-added products. [ABSTRACT FROM AUTHOR]

This work assesses a chemical plant for the conversion of biogas into negative emission "emerald hydrogen" via electrified reforming and CO 2 separation. Electrification of the reformer allows for enhanced syngas production, compact reactor designs and flexible operation, thanks to the avoidance of combustion and heat transfer through pressure walls. The integration of the process with solar and wind power generation has been assessed by part-load process simulations and plant sizing and operation optimization through yearly simulations with hourly discretization. Different European locations with different wind and solar availabilities were assessed considering (i) short- and long-term cost scenarios for renewables and battery technologies and (ii) different plant size (from 390 to 3900 Nm3/h of biogas capacity). The overarching scope of the paper is to calculate the cost of the produced hydrogen and the economic value of flexibility for plants installed in different locations, under different cost scenarios. At design load, the assessed process consumes 17.7 kWh of electricity per kg H2 and retains 96% of the biogas chemical energy in the produced hydrogen. Additionally, 76% of the biogenic carbon is recovered as high-purity liquid CO 2 , achieving up to −9 kg CO2 /kg H2 negative emissions. When powered with 95% of renewable energy, hydrogen production cost ranges from 2.5 to 2.9 €/kg for a long-term REN cost scenario and large-scale flexible plant to 5.9–7.1 €/kg for a short-term REN cost scenario and small-scale inflexible plants. For small-scale plants, flexibility allows to reduce the hydrogen production cost by 11–16% with respect to the inflexible plant in the short-term renewables cost scenario and by 1–4% in the long-term cost scenario. For large-scale plants, the adoption of a flexible plant leads to a reduction of 17–23% of the hydrogen cost in the short-term scenario and of 6–22% in the long-term scenario. Operational flexibility of electrified reforming allows reducing the cost of negative-emission bio-hydrogen by 1–23%, depending on location and cost scenario. [Display omitted] • Process engineering study with off-design model. • Economic optimization of flexible process with PV, wind, BESS and gas storages. • 17.7 kWh/kg H2 of electric consumption and up to −9 kg CO2 /kg H2 negative emissions. • H 2 cost of 2.5–6.2 €/kg depending on location, REN cost scenario and plant capacity. • Flexibility reduces H 2 cost by 1–23% depending on location and REN cost scenario. [ABSTRACT FROM AUTHOR]

Recovering energy from biomass and treating organic waste can be done effectively through a biogas digester system. However, monitoring the performance and control of the system to produce biogas is possible through the online process. Therefore, this study developed a novel low-cost gas and temperature profiling system (GTPS) and data acquisition system (DAS) used in biogas digester. The GTPS is designed to monitor and record the amount of methane (CH4) and carbon dioxide (CO2), the main constituent of biogas, from 0 to 100% and to measure the slurry temperature in the digester using a K-type thermocouple. To test the developed monitoring system, the biogas yield (%) and temperature were monitored, and the result obtained agreed with that reported and obtained in the literature (50–70% and 30−40%) for CH4 and CO2, respectively, followed by the desired mesophilic temperature condition for biogas production (20–35 °C). The study employed an RS-232/RS-485 converter for data communication and a low-cost thermocouple module (isolated analog input) that was installed in the data acquisition system. Interestingly, the application of the converter equipment has never been used in any study on monitoring a biogas digester. [ABSTRACT FROM AUTHOR]

The USA has committed to cutting its emissions of methane, an extremely potent greenhouse gas, by at least 30% by 2030 (‘30 × 30’). This is part of the Global Methane Pledge, signed by 155 countries, to keep global warming within 1.5 °C and thereby to forestall the disastrous effects of ‘runaway climate change’. It will be a major challenge for the USA to reach 30 × 30 and there is no consensus on how to do so. This paper provides a concrete, data‐driven roadmap to indicate how to reach 30 × 30 feasibly, focusing on two enormous sources of methane emissions: organic waste and oil and gas production. It calculates that building approximately 4700 anaerobic digesters (ADs) to process food waste and animal manure would cost about $74.2 billion in capital expenditure (capex) and cut 13.6% of total US methane emissions per year. On average, each project would take roughly 2–6 years to build. Of the various methane mitigation measures analyzed in the oil and gas sectors, the most impactful would be full compliance with the US Environmental Protection Agency's (EPA's) revised New Source Performance Standards (NSPS) for oil and gas production by 2029. This would cut 17.5% of total US methane emissions annually, at a cumulative capex of $20.7 billion from 2024 to 2029. Together, the 13.6% cut from food waste and manure ADs and the 17.5% cut from full NSPS compliance would amount to a 31.5% reduction, exceeding the 30 × 30 goal. Greater clarity from the federal government on funding eligibility and additional incentives would accelerate the buildout of ADs. [ABSTRACT FROM AUTHOR]

This paper presents a simulation model for determining the most suitable type of microbiogas plant for small local communities on Slovenian farms, focusing on the efficient processing of organic waste. This model uses various input parameters, including different types and quantities of slurry and corn silage. Four different scenarios were developed to represent potential plant sizes, each evaluated using key economic indicators: net present value, breakthrough price, and internal rate of return. A scenario sensitivity analysis was conducted to assess the effects of changes in investment costs, fluctuations in energy prices, and the addition of corn silage to the anaerobic digestion process. The results highlight significant differences in economic viability across the scenarios, with some demonstrating positive financial outcomes and shorter payback periods and others indicating potential financial risks and longer recovery times under certain conditions. The analysis suggests that smaller micro biogas plants may struggle to achieve profitability without optimizing input ratios or reducing costs, whereas larger plants show more favorable economic indicators, provided certain conditions are met. Furthermore, the economic efficiency improves when adding maize silage to the fermentor mixture. [ABSTRACT FROM AUTHOR]

Anaerobic fermentation (AF) can effectively dispose of kitchen waste (KW) without the shortcomings of traditional methods such as incineration and sanitary landfill. However, KW has a high organic content, which easily leads to acidification and ammonia inhibition during digestion. To mitigate this issue, anaerobic co-digestion (AnCoD) with other substrates helps to adjust the carbon to nitrogen ratio (C/N) and enhance the stability of the reaction system. The hydrolysis of substrate is the rate-determining step in AF, prompting the adoption of necessary pretreatment methods to accelerate substrate hydrolysis. Among physical, chemical, and enzymatic pretreatments, the latter is more efficient. And the enzymatic pretreatment does not need additional equipment or reagents. Therefore, coupling enzyme treatment before AnCoD received more attention. In this review, we conduct a comparative analysis of the biogas production efficiency of enzymatic pretreatment against other pretreatment methods. The challenges and strategies concerning enzymatic pretreatment coupled with AnCoD system were discussed. Finally, the pilot-scale study and industrial application for KW co-digestion are also analyzed. [ABSTRACT FROM AUTHOR]

The industrial sector of Pakistan is currently facing severe load-shedding, which ultimately affects its unit production. The greater dependency on conventional energy resources (Thermal, Nuclear, etc.) results in higher production costs and environmental pollution. A sustainable, cost-effective, and environment-friendly solution can help the industrial growth of Pakistan. This article proposes an optimal hybrid energy system (HES) for the industrial sector of Pakistan to overcome the mentioned challenges. The proposed HES is developed in HOMER Pro. Three different energy cases (Case I: Existing energy system including a utility grid and diesel generator, Case II: On-grid Biogas system, and Case III: On-grid PV system with batteries) are considered for the Gourmet food Industry in the Sundar Industrial estate, Pakistan. The Load profile of the selected site was calculated through on-site visits and data provided by the designated utility grid feeder. The analysis shows that Case III is more effective than other cases, indicating reduced Net Present Cost (NPC), Cost of Energy (COE), and Operating Cost (OC) to $ 19.2 million, $0.034/kWh, and $ 573,371/year respectively. Moreover, the On-grid PV system with batteries (Case III) provides an environmentally friendly solution by reducing 63.82% by and 62.22% . Comparing the sensitivity analysis for various grid sell-back prices ($0/kWh, $0.043/kWh, $0.061/kWh, and $0.09/kWh), Case III is more cost-effective than Case II. The revenue generation in Case III is $128,499.41/yr, considering the supply of excess electricity into nearby small industrial loads at $0.065/kWh, this indicates that installing optimal HES in industries will not only help in overall cost reduction but also support in mitigating environmental pollution and load shedding. [ABSTRACT FROM AUTHOR]

Biogas is a type of biomass energy source, primarily composed of methane and carbon dioxide. It is generated through the controlled anaerobic digestion of manure or other organic residues. As a cleaner alternative to conventional fuels, fully purified biogas can produce approximately 36.68 MJ/m3 of en.ergy. As the separation of CO2/CH4 in biogas became an important part of the energy industry, we used membrane separation technique to study its separation methods. At first, 3,3′‐dihydroxy‐4,4′‐diamino‐biphenyl (HAB) and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) were polymerized by open‐loop as polyamide acid macromolecules. Then it was divided into two research routes. One was condensation to polyimide (PI) membranes directly and then thermal rearrangement (TR); the other one was ionic liquid (IL) added before condensation and thermal rearrangement. Through adjusting the thermal rearrangement temperature, different modified polyimide membranes were obtained and tested their separation performance of CO2/CH4. For the result of the test, the best one, membrane HAB‐6FDA‐IL‐TR400, could reach a good separation performance as PCO2 = 403.80 Barrer, αCO2/CH4 = 82.35. It was beyond the Robeson's 2019 upper limit and proved that the modification by IL and thermal rearrangement was benefit for the separation performance of polyimide membranes. [ABSTRACT FROM AUTHOR]

This paper presents a bibliometric review on biogas reforming for the production of sustainable aviation fuel. The central themes are catalyst stability and syngas H 2 /CO ratio. It begins with a summary of bibliometric data, literature trends, and most productive agents. Followed by citation analysis on dry reforming (DR) and steam reforming (SR), including internal reforming in fuel cells. Then, a statistical exploration of literature data on reforming in nickel catalysts, followed by the thermodynamic effects of temperature, pressure, and H 2 O/CH 4 ratio. For Sustainable Aviation Fuel (SAF) production, steam reforming appears as the best option. The biggest gaps in the biogas reforming literature are kinetic studies and pressure effect assessments, for scale-up. [Display omitted] • Steam reforming syngas is most appropriate for Sustainable Aviation Fuel production. • Dry reforming values CO 2 but still presents major challenges to industrial implementation. • Biogas reforming literature is poor in studies of the effect of pressure, and reaction kinetics. • Nickel loads have negative correlation with catalyst activity. The H 2 O concentration, with the conversion and H 2 /CO ratio. [ABSTRACT FROM AUTHOR]

Biogas offers significant benefits as a renewable energy source, contributing to decarbonization, waste management, and economic development. This comprehensive review examines the historical, technological, economic, and global aspects of biomethane production, focusing on the key players such as China, the European Union, and North America, and associated opportunities and challenges as well as future prospects from an Australia perspective. The review begins with an introduction to biogas, detailing its composition, feedstock sources, historical development, and anaerobic digestion (AD) process. Subsequently, it delves into major biomethane production technologies, including physicochemical absorption, high‐pressure water scrubbing (HPWS), amine scrubbing (AS), pressure swing adsorption (PSA), membrane permeation/separation (MP), and other technologies including organic solvent scrubbing and cryogenic separation. The study also discusses general guidelines of techno‐economic assessments (TEAs) regarding biomethane production, outlining the methodologies, inventory analysis, environmental life cycle assessment (LCA), and estimated production costs. Challenges and opportunities of biogas utilization in Australia are explored, highlighting and referencing global projections, polarization in production approaches, circularity in waste management, and specific considerations for Australia. The review concludes discussing future perspectives for biomethane, emphasizing the importance of technological advancements, policy support, and investment in realizing its full potential for sustainable energy and waste management solutions. [ABSTRACT FROM AUTHOR]

Biogas, a fuel derived from organic waste, has gained popularity as a sustainable energy source. The adaptability of biogas allows its utilization for electricity and heating. This study aims to evaluate the risk of biogas leakage using ALOHA gas dispersion modeling and Bowtie analysis to identify hazard zones and evaluate the effectiveness of preventive and mitigation measures. The research method using Gas dispersion modeling in ALOHA software can simulate the spread of leaked biogas, identify potential hazard zones, and inform emergency response planning. The results show that gas dispersion reaches up to 296 meters from the leak source in a worst-case scenario without ignition, with significant implications for safety. The ignition scenario produces high thermal radiation, further exacerbating the risk. In conclusion, these findings highlight the intolerable risk of biogas leakage, requiring comprehensive risk mitigation measures. This study recommends the implementation of a robust control system, routine maintenance, and emergency response plan to ensure the safety and sustainability of biogas facility operations. [ABSTRACT FROM AUTHOR]

This critical review examines the potential of household biogas technology in Africa, focusing on biogas production and techno‐economic feasibility studies. The review highlights the benefits of biogas technology, including renewable energy generation, waste management, and improved public health. A significant portion of Africa's rural population, approximately 60%, grapples with limited access to reliable power sources. The study analyzes various biogas production systems, including anaerobic digesters and biomass gasifiers, and evaluates their economic viability in different African contexts. The review identifies key factors influencing the adoption of household biogas technology, including policy and regulatory frameworks, financing mechanisms, and public awareness. Biogas production stands out as one of the promising renewable energy sources. However, it also discusses the challenges and limitations of implementing this technology on a continental scale. The study analyzes various biogas production systems, including anaerobic digesters and biomass gasifiers, and evaluates their economic viability in different African contexts. The review identifies key factors influencing the adoption of household biogas technology, including policy and regulatory frameworks, financing mechanisms, and public awareness. The study concludes by recommending strategies for scaling up biogas technology in Africa, including capacity building, technology transfer, and innovative financing models. The review aims to provide a comprehensive resource for researchers, policymakers, and practitioners working towards sustainable energy solutions in Africa. [ABSTRACT FROM AUTHOR]

The biomethane potential of insect frass and leachates from waste (larvae feedstock) stockpile was evaluated. Frass was derived from a black soldier fly larvae (BSFL) operation that uses a fruit and vegetable waste diet. The two waste streams were characterized and the results of their compositional, proximate, and ultimate analysis were used in estimating methane yields from these materials. The estimated biomethane potential (BMP) of the frass ranged 149–275 L/kgVS depending on the calculation method used. This result compares well with that of empirical studies for cow manure whose BMP ranges 110–275 L/kgVS. Cow manure is the most popular biogas feedstock globally. Leachates reported an estimated BMP of 150 L/kgCOD. We conclude that it may be technically feasible to produce biogas from BSFL frass and from fruit and vegetable waste leachates. However, standard BMP experiments and semicontinuous pilot studies are still necessary before commercialization of these findings. These extra tests are executed to validate these findings and ascertain the life cycle attribute and long‐term process stability and hence determine the economics of using these potential substrates for biogas production as a strategy to implementing circularity in the fruit and vegetable industry. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: During this energy transition, research is being done to develop sustainable ways to support the shift to a decarbonized energy and production system. These ways include using renewable energy sources to promote circularity in products, green technologies, and safer procedures. Anaerobic digestion of palm oil mill effluent is a beneficial process for generating biogas, while the waste can also be utilized as fertilizer. The biogas can be further refined into biomethane, a valuable resource commonly used in transportation and power generation. The objective of this study is to examine the enhancement of biogas from Palm oil mill effluent and the elimination of sludge nutrients by utilizing microalgae Chlorella vulgaris. The microalgae will be cultivated in a modified photobioreactor to enhance the capture of carbon dioxide. METHODS: The study utilized anaerobic batch reactor digesters. A modified photobioreactor, consisting of two columns separated by a membrane, was developed for the technological advancement of biogas upgrading, specifically for carbon dioxide capture and biogas upgrading. A technological gap in biogas upgrade technology innovation is filled by the improved photobioreactor. To optimize the bio-fixation of carbon dioxide from flue gas, it is essential to carefully select a suitable strain of microalgae that possesses both a strong ability to absorb carbon dioxide and a high tolerance to varying concentrations of this gas. By choosing the right strain, the efficiency of carbon dioxide removal can be significantly enhanced. Since Chlorella vulgaris microalgae have demonstrated this potential, they were chosen for this investigation. Microalgae also play a role in removing nutrients contained in the sludge. FINDINGS: Numerous chemical and biological methods have been used to upgrade biogas. Results of biological upgrading of biogas from palm oil mill effluent have been reported, with carbon dioxide removal reaching 89 percent until the methane concentration of the biogas is upgraded to 84 percent. The highest biomass of 1,835 grams per liter was achieved by culturing the microalgae Chlorella vulgaris in laboratory-scale photobioreactors. In this study, the application of 15 percent volume per volume biogas with an optical density of 0.4 was found to be optimal for the growth of the microalgae. The cultivation period lasted for 14 days. The peak biomass production was observed due to the achievement of a remarkable 98 volume per volume efficiency in carbon dioxide removal, which subsequently led to a significant rise in methane content, reaching 60 percent. The enhanced biogas achieved a peak methane content of 98 percent, indicating a significant improvement in quality. CONCLUSION: The findings of this study, conducted using a modified photobioreactor, indicate that Chlorella vulgaris demonstrated high efficacy in the removal of carbon dioxide, with a rate of up to 90 percent. Additionally, it exhibited remarkable performance in upgrading biogas derived from palm oil mill effluent, achieving a conversion rate of up to 98 percent. The optical density of microalgae at 0.4 played a crucial role in these processes. Furthermore, Chlorella vulgaris showcased its ability to effectively eliminate nutrient nitrogen, reaching a removal rate of 90 percent at an optical density of 0.2. Moreover, it demonstrated a phosphate removal rate of 80 percent at an optical density of 0.4. [ABSTRACT FROM AUTHOR]

Water hyacinth is one of the most significant sources of biomass in tropical regions that can be used to create biogas. This strategy aims to improve the sustainability, precise energy content, and ease of transport of the original biofuel feedstock, as well as to extract gases. An experimental investigation on the biomethanation of water hyacinth took place in a semi-batch digester. Temperature, stirring speed, and catalyst concentration all have an impact on the rate of biogas production. The catalyst has been discovered to primarily boost the rate of biogas production from water hyacinth (Eichhornia crassipes). As the catalyst is used here to boost up the biomethanation reaction, the effect of the catalyst on different kinetic parameters is investigated. The key conclusions of the research indicate that the maximum value of acidogenic cell mass concentration is 0.13 kg/m3d while the minimum value of methanogenic cell mass concentration is 0.014 kg/m3d at 50 ppm catalyst concentration. Moreover, the maximum specific growth rate of the entire process increases as the catalyst concentration rises, reaching a maximum level of 0.312 d−1 at a 50 ppm catalyst concentration. This is proof that using a catalyst can expedite the biomethanation process. As the catalyst concentration increases, so does the overall biomass concentration. Since it increases the precision of the parameter estimates, the simultaneous estimation of the parameters is a crucial part of the estimation process. [ABSTRACT FROM AUTHOR]

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Slaughterhouse waste (SW) poses significant environmental challenges due to its complex composition, but anaerobic digestion offers a way to recover valuable biogas from SW. This study investigated the anaerobic co-digestion of beef cattle slaughterhouse waste (BCSW) with either cattle feces (CF) or swine slurry (SS). The biomethane potential, maximum methane yield (Mmax), lag phase duration, and effective digestion time (Teff) for the individual substrates and the combinations were analyzed. BCSW alone exhibited Mmax of 578.5 Nml CH4/g VSadded with a lag phase of 11 days, while CF and SS alone exhibited Mmax of 397.2 and 289.8 Nml CH4/g VSadded, respectively. Co-digestion of BCSW and SS resulted in Mmax increase of 48–75.5%, with negligible effects on Teff compared to solitary SS digestion. Similarly, co-digestion of BCSW and CF increased Mmax by 6.2–40.4%, with no significant impact on Teff compared to solitary CF digestion. However, both co-digestions led to a reduction in Mmax (12.1–27%) when compared to BCSW digestion alone. Co-digestion with SS shortened the lag phase duration by 2.8–7.8 days and accelerated Teff by 5.8–8.3 days due to SS's high concentrations of essential micronutrients like cobalt and nickel which aid digestion. This study concluded that co-digestion of BCSW with SS is an effective strategy for enhancing methane production and digestion efficiency, offering a viable approach for proper disposal of BCSW while improving biogas output. [ABSTRACT FROM AUTHOR]

Textile waste is becoming among the most polluting waste in the world, discarded mostly in landfills. Valorizing textile waste via anaerobic digestion (AD) helps conserve resources, reduce environmental impact, and foster a circular economy. Although several reviews have discussed textile waste AD, there is a lack of detailed understanding of the challenges encountered during textile waste AD. Therefore, the goal of this review is to focus on challenges encountered and possible solutions for those challenges for biogas and fertilizer conversion via AD. Potential strategies include chemical, biological, and thermal pretreatments that significantly increase the digestion process. Co‐digestion of natural textile waste, cotton, and wool with carbon and nitrogen‐rich substrates improves AD efficiency by twofold. Moreover, separating polyester from polycotton and textile dye removal via solvent and advanced oxidation processes significantly increases methane yield compared with untreated textile waste. This review can aid in analyzing suitable methods to optimize the biogas production of textile waste via AD. [ABSTRACT FROM AUTHOR]

A promising approach for carbon dioxide (CO2) valorization and storing excess electricity is the biological methanation of hydrogen and carbon dioxide to methane. The primary challenge here is to supply sufficient quantities of dissolved hydrogen. The newly developed Inverse Membrane Reactor (IMR) allows for the spatial separation of the required reactant gases, hydrogen (H2) and carbon dioxide (CO2), and the degassing area for methane (CH4) output through commercially available ultrafiltration membranes, enabling a reactor design as a closed circuit for continuous methane production. In addition, the Inverse Membrane Reactor (IMR) facilitates the utilization of hydraulic pressure to enhance hydrogen (H2) input. One of the process's advantages is the potential to utilize both carbon dioxide (CO2) from conventional biogas and CO2-rich industrial waste gas streams. An outstanding result from investigating the IMR revealed that, employing the membrane gassing concept, methane concentrations of over 90 vol.% could be consistently achieved through flexible gas input over a one-year test series. Following startup, only three supplemental nutrient additions were required in addition to hydrogen (H2) and carbon dioxide (CO2), which served as energy and carbon sources, respectively. The maximum achieved methane formation rate specific to membrane area was 87.7 LN of methane per m2 of membrane area per day at a product gas composition of 94 vol.% methane, 2 vol.% H2, and 4 vol.% CO2. [ABSTRACT FROM AUTHOR]

Biorefineries are novel biotechnological routes designed to generate sustainable processes from renewable raw materials. The valorization of orange peel waste (OPW) provides high-value products based on their composition. The economic optimization of biorefineries through conceptual design and generation of superstructures based on the analysis of processing units is a topic of great interest. This work aimed to obtain the most profitable biorefinery through economic optimization strategies based on high-value-added products from OPW. Two stages were considered: The first stage consisted of the conceptual design of multiple OPW processing units (production of essential oil, mucic acid, phenolic compounds, biogas, among others). An OPW flow rate of 140 kg/h was selected as the base case. From the stand-alone units, a biorefinery superstructure (second stage) was designed. Finally, the units with the best mass and energy results were selected in order to maximize the net present value (NPV) and obtain an optimal biorefinery configuration. The results evidenced that the production of essential oil and biogas presented the best yields (2.61 mL and 0.028 m3 per kg OPW, respectively). This biorefinery configuration obtained an NPV of −7.7 mUSD from the base case. Through the evaluation of the different superstructure configurations, the combined production of essential oil, biogas, and mucic acid and a scale-up of over 22 times the base case generated the minimum processing scale. Under a Colombian context, the implementation of the biorefineries analyzed are promising since the minimum processing scale contemplated only 8.8% of the OPW production. Efforts to increase yields and decrease capital and operating expenses while keeping environmental impacts low should be pursued. [ABSTRACT FROM AUTHOR]

Biogas plays a significant part in replacing solid biomass and fossil fuels for cooking. However, the implementation of appropriate policies to promote the development of biogas plants is hindered by a lack of adequate assessment of the biogas potential in Nepal. Thus, we estimate the potential of biogas production at the district level of Nepal from available waste biomass, including livestock manure, agricultural residues, and organic fraction of municipal solid waste (OFMSW). Our estimates show the theoretical potential of biogas production from livestock manure of 1890 million m3 year−1, agricultural residues of 2290 million m3 year−1, and OFMSW of 234 million m3 year−1. The total biogas production is 4412 million m3 year−1, equivalent to 153 million liquefied petroleum gas (LPG) cylinders yearly. Using this biogas potential to replace LPG and solid biomass for cooking could result in avoided CO2, CO, and PM2.5 emissions of 6.3 million tons year−1, 0.4 million tons year−1, and 0.04 million tons year−1, respectively. Our findings suggest that the Terai districts of Morang, Sunsari, Saptari, and Banke, as well as the Hilly districts of Kavrepalanchok, Dhading, and Nuwakot, have a significant amount of biogas‐producing potential. Utilising this potential could also contribute to achieving several Sustainable Development Goals and a clean cooking energy transition in Nepal. For this, governments need careful planning, designing, policy support, and facilitation on bio‐resource management and utilisation at the local level. [ABSTRACT FROM AUTHOR]

Food waste (FW) biotransformation into bioenergy has garnered a lot of scientific interest as a way to address the energy crisis and trash disposal issues. FW is converted into biogas, a gaseous combination of biomethane and carbon dioxide. In order to valorize FW, anaerobic digestion (AD) with combined pretreatment (hydrothermal (HT) and ultrasonic (US)) is used as a potential method. Three digesters were investigated: the control (unpretreated), HT(121°C) + US, and HT(134°C) + US, respectively. Based on changes in the combined pretreatment conditions, the paper assessed the methane productivity. Furthermore, kinetic modeling was evaluated with six kinetic models. The results show that the HT pretreatment at 121°C combined with US improves the volatile solid (VS) removal to 73 ± 5% and the methane yield to 529.7 ± 11 NmL/gVS. Both the Transference model and the first order have the greatest fits in terms of R2, and they also have the best fits in terms of relative errors, and methane production rate, respectively. The combined pretreatment has a positive impact on increasing methane yield as well as stabilizing the anaerobic digestion process. [ABSTRACT FROM AUTHOR]

Copyright of Advances in New & Renewable Energy is the property of Editorial Office of Advances in New & Renewable Energy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)