The objective of this study was to quantitatively assess the energy recovery potential from both biogas and the incineration of dewatered sludge, aiming to meet the energy demand of a small municipal wastewater treatment plant (MWTP) with a treatment capacity below 50 L s-1. The energy potential of sludge incineration was characterized based on its gross calorific value, while energy production from biogas generated during the anaerobic digestion of municipal sludge was also evaluated. In addition, the feasibility of using the produced biogas for the thermal drying of dewatered sludge was analyzed. The results indicate that biogas utilization could generate 1462 kWh d-1, corresponding to 83.17% of the total electricity consumption of the MWTP. Furthermore, the mass reduction achieved through sludge drying resulted in an annual cost savings of US$ 27,763 related to sludge disposal. The incineration of dried sludge could generate an additional 432.52 kWh d-1. Overall, the combined energy recovery strategy could lead to a reduction of approximately 150 t CO2eq year-1 in greenhouse gas emissions due to methane avoidance at the studied MWTP. These findings suggest that such integrated approaches can encourage investments in MWTPs aimed at achieving energy self-sufficiency while enhancing environmental performance.

Hydrogen sulfide (H 2 S) removal (desulfurization) is a critical prerequisite for biogas utilization. H 2 S formation during anaerobic digestion is substrate-dependent and can fluctuate substantially, complicating subsequent desulfurization. Digestate, the nutrient-rich liquid residue after anaerobic digestion, can serve as microbial inoculum and trickling solution for biogas desulfurization in biotrickling filters (BTF). In this study, a two-stage pilot-plant was operated under real-life conditions at an agricultural biogas facility to evaluate an anoxic desulfurization strategy under transient H 2 S inlet loads (IL). In the first stage, partial nitrification (PN) of diluted digestate was performed in a 900 L batch reactor. Ammonium (NH 4 + ) naturally present in digestate was partially nitrified, achieving average (nitrite) N-NO 2 − and (nitrate) N-NO 3 − production rates of 2.1 ± 1.3 mg L −1 h −1 and 0.5 ± 0.3 mg L −1 h −1 , respectively. In the second stage, nitrified digestate containing NO 3 − and NO 2 − served as the electron acceptor for biological H 2 S oxidation in a BTF, replacing oxygen. The BTF exhibited stable performance under transient shock H 2 S loads, characterized by abrupt step increases in inlet load (e.g. from 3.3 to 83.3 gS-H 2 S m −3 BTF h −1 ), while maintaining a removal efficiency of 96.1% immediately following the shock increase. Microbial community analysis of the BTF packing revealed a diverse consortium dominated by Proteobacteria (29.7%), Campilobacterota (10.2%), Bacteroidota (14.2%), and Firmicutes (17.3%), including sulfur-oxidizing and denitrifying genera such as Paracoccus (8.1%), Sulfurimonas (7.7%), and Sulfurovum (2.5%), underscoring organisms support for anoxic BTF function. This study addresses a key literature gap by evaluating a pilot-scale system under transient H 2 S loads, integrating in situ electron acceptor generation, enhancing overall process sustainability. • During nitrification, NH 4 + and O 2 control NO 2 − - and NO 3 − production rates. • NO 2 − - and NO 3 − -rich digestate is a viable trickling liquid for biogas desulfurization. • Nitrification is the rate-limiting step in the integrated process. • The BTF maintained stable H 2 S RE under abrupt IL spikes at N-NO 2 − /N-NO 3 − > 20 mgL −1 . • Paracoccus is the most abundant genus in the BTF (8.1%).

Wastewater treatment plants increasingly rely on anaerobic digestion and biogas utilization to reduce operational costs, enhance energy self-sufficiency, and support circular-economy objectives. This study provides a comprehensive, year-round assessment of sludge production, sludge characteristics relevant to digestion, biogas generation, and energy performance at a municipal wastewater treatment plant. The plant generated on average 68.0 m3/d of thickened primary sludge and 24.0 m3/d of excessive sludge (total 92 m3/d), with low daily variability throughout the year. Biogas production remained highly stable, with an annual average of approximately 1300 m3/d and limited daily variation. Although monthly averages ranged from 1004 to 1728 m3/d, within-month variability was low to moderate, indicating that digestion processes responded consistently to changes in sludge quantity and composition. The weak correlation between sludge volume and biogas output (r = 0.29) showed that, besides sludge quantity, factors such as organic content and digester operating conditions also influence biogas yield. Energy performance indicators demonstrated strong self-sufficiency potential: the facility produced 1,095,047 kWh of electricity, covering 56.72% of its annual demand. The high coefficient of determination for self-sufficiency (R2 = 0.871) confirmed a strong linear relationship between biogas-derived energy production and reduced grid dependence. Operational correlations further highlighted system coherence, with cogenerator and boiler usage strongly inversely related (r = −0.85) and biogas production positively associated with heat output (r = 0.66). Overall, the results demonstrate a stable and efficient sludge-to-energy system and provide a detailed dataset supporting future optimization of anaerobic digestion processes.

Rural households in cold regions still rely heavily on coal for cooking and domestic hot water, while single renewable energy sources suffer from intermittency and limited system-level assessment. This study proposes a solar–biogas complementary energy supply system integrating evacuated-tube solar collectors, an above-ground anaerobic digester, thermal storage, and biogas utilization for rural residential applications in Minqin, Northwest China. A dynamic system-wide model was developed by coupling TRNSYS with nonlinear representations of anaerobic fermentation and biogas boilers, enabling hour-by-hour simulation of energy production, conversion, storage, and consumption. Field measurements were used for validation, and the root mean square deviation between simulated and measured temperatures and gas production remained below 10%. During the heating season, the solar subsystem supplied 10% of the digester heating demand and 90% of the domestic hot-water load, while the biogas subsystem contributed 9.29% and 90.71%, respectively. The system delivered 4728.96 MJ of heat against a seasonal demand of 4636.22 MJ, fully meeting user requirements. A comprehensive 3E (energy–environment–economic) assessment shows that, compared with traditional rural energy supply modes, the proposed system reduces CO2 and NOx emissions by 65.85% and 98.13%, respectively, and demonstrates favorable economics with a benefit–cost ratio of 2.41 and a discounted payback period of 3.27 years. The proposed modeling and evaluation framework provides a replicable solution for clean energy substitution and circular waste utilization in rural areas.

Cost effective utilization of renewable biogas requires that the siloxane content be maintained at low parts-per-billion (ppb v ) levels. Infrared (IR) spectrometric methods offer the potential for near-real-time siloxane quantification but are difficult to implement in the presence of certain spectral interferents such as oxygenated volatile organic compounds (VOCs). In this report, a novel two-step gas-stream modification process is implemented in the quantification of siloxanes in biogas by Fourier transform IR spectrometry. The method is demonstrated for synthetic biogas comprising a mixture of methane in nitrogen, with linear (L3) and cyclic (D4) siloxanes present at 100 ppb v levels, and ethanol, acetone, and acetic acid added as model VOCs at 100 parts-per-million (ppm v ) levels. The first step in the process involves sparging the biogas through water to significantly reduce VOC concentrations. The second step removes residual VOCs and the siloxanes by passage of the gas stream over a low temperature metal oxide catalyst. IR spectra acquired after sparging and after passage over the catalyst serve as near-real-time biogas sample and biogas blank spectra, respectively. The biogas blank spectrum and standard siloxane spectra are next used in a simple least squares reconstruction of the biogas sample spectrum for siloxane quantification. Limits of detection for L3 and D4 are determined to be 9.3 and 6.3 ppb v , respectively, while limits of quantification are 31 and 21 ppb v . This method will facilitate the development of simple, inexpensive IR-based devices for on-line and near-real-time monitoring of siloxanes in industrial biogas streams.

West Nusa Tenggara Province (Nusa Tenggara Barat/NTB) has demonstrated a strong commitment to reducing greenhouse gas (GHG) emissions through various policies and strategic documents. However, among the many contributing sectors, the livestock sector—particularly cattle farming—has not received sufficient attention, despite its substantial contribution to GHG emissions in line with the increasing cattle population, which has exceeded 1.3 million heads. Improperly managed cattle manure contributes significantly to methane (CH₄) emissions, which have a much higher global warming potential than carbon dioxide (CO₂). This study aims to analyze the potential utilization of cattle manure as a biogas feedstock, estimate the amount of energy generated, and assess its contribution to GHG emission reduction in supporting the achievement of Net Zero Emissions (NZE) in NTB Province by 2050. The research employs a mixed qualitative and quantitative descriptive approach through literature review, secondary data analysis, and limited interviews with the NTB Provincial Office of Energy and Mineral Resources and the Regional Development Planning Agency (Bappeda). The results indicate that with 6,150 constructed biogas units utilizing approximately 12,300 cattle, the potential GHG emission reduction reaches 26,658.65 tons CO₂e per year, equivalent to about 0.625% of the total emission potential from the cattle livestock waste sector in NTB. This emission reduction is derived from methane (CH₄) emission avoidance and the substitution of fossil fuels such as liquefied petroleum gas (LPG). In addition to climate mitigation benefits, biogas utilization provides economic advantages through household energy savings and supports the implementation of a circular economy by utilizing bio-slurry as organic fertilizer. Although the current level of biogas utilization remains relatively low compared to its potential, biogas technology has proven to be a strategic and sustainable solution for livestock waste management, renewable energy development, and climate change mitigation efforts in NTB Province.

The transition toward market-oriented renewable energy policies has increased the demand for flexible operation of biogas plants (BGPs), particularly under Japan’s Feed-in Premium (FIP) scheme. This study evaluates the technical performance and revenue potential of integrating hydrogen production into a dairy-manure-based BGP, focusing on steam reforming (SR) and electrolysis (EL) pathways. An energy system optimization model was developed using the Open Energy Modelling Framework (OEMOF) to simulate coordinated operation of biogas combined heat and power (CHP), hydrogen production, heat supply, and storage under electricity spot market conditions in Hokkaido, Japan. Sensitivity and scenario analyses were conducted to examine hydrogen production behavior, system-level resource allocation, and revenue performance under varying hydrogen prices and FIP levels. The results show that EL enables price-responsive switching between electricity supply and hydrogen production, resulting in dynamic hydrogen output and high sensitivity to conditions. In contrast, SR provides stable hydrogen production through continuous biogas utilization, achieving biogas throughput but limited responsiveness to price fluctuations. A System-level trade-off between conversion flexibility and direct fuel utilization efficiency was identified. These findings indicate that hydrogen pathway selection in farm-scale BGPs should be treated as a system design decision shaped by market exposure, operational objectives, and risk tolerance under the FIP framework.

Anaerobic digestion of organic waste offers renewable energy and waste-management benefits, relevant to multiple SDGs. This study evaluates a proposed 50 t/d farm-based biogas plant co-digesting poultry manure (PM) and fruit/vegetable waste (FVW) in South Africa. Five substrate blends (100% PM, 100% FVW, and three PM–FVW mixtures) and three biogas utilization routes (100% electricity via a combined heat and power (CHP) system, 50/50 CHP–biomethane, and 100% biomethane) were modelled in a combined techno-economic analysis (TEA) and life-cycle assessment (LCA) framework. Key metrics included GWP100 per ton of feedstock and the project’s internal rate of return (IRR), debt service coverage ratio (DSCR), and net present value (NPV) over a 20-year project lifespan. Under base-case assumptions, electricity-led pathways yield the highest returns; in the best case, 80% FVW + 20% PM with 100% CHP achieves a project IRR of 10% with a minimum DSCR of 2.4. The LCA shows total GWP100 ranging 118–168 kgCO2-eq/t, minimum for pure FVW, maximum for pure PM, and clearly identifies digestate handling as the dominant emission source. Overall, the CHP-only configuration emerges as the most financeable option at this scale, and emphasis on closed digestate management is recommended to minimize emissions.

Assessing biogas valorization from municipal organic waste in India: Integrated environmental-economic analysis.

Biogas upgrading to pipeline-grade methane (>95% CH4) represents a critical pathway for enhancing the utilization and value of biogas. Direct methanation of biogas is promising, but due to the performance limitations of conventional nickel-based methanation catalysts, reactant circulating or multi-stage process is required as engineering compensation. Here, through process simulation and economic analysis, we demonstrate substantial economic benefits of the single-stage methanation process over conventional routes in terms of both capital investment and operation costs. A structured inverse catalyst with CeZrOx/Ni inverse configuration grown on porous Ni-foam featuring specific surface area and water removal enhancements over powder inverse catalyst is developed and realizes scale-up. The remarkable low-temperature activity of the structured inverse catalysts achieves a near-equilibrium conversion of 97.8% CO2 in biogas, allowing the production of pipeline-grade methane through the single-stage biogas methanation process. With the innovation of catalysts and process, the price of low-carbon methane produced from biogas with industrial by-product hydrogen is competitive with natural gas.

This study investigates the role of biogas and biomethane in accelerating the decarbonization of district heating systems in Europe. A structured literature review combined with two representative case studies evaluate technological, economic, and environmental performance across different system scales. The Meppel optimization model developed for the Netherlands and the large-scale Backbone energy system modelling framework for Finland are compared to identify methodological synergies and operational insights for integrating bioenergy into heating networks. The results show that biogas-based combined heat and power systems can reduce carbon dioxide emissions by more than 70 percent compared with fossil-based alternatives and significantly improve local energy security, especially when coupled with heat pumps and thermal storage. Large-scale modelling further demonstrates that biomethane and bioenergy resources provide valuable system flexibility, facilitating sector coupling and supporting the balancing of variable renewable electricity production. This study’s main contribution is an integrated comparative assessment at two different scales (local and regional), linking operational data, modelling, and performance results to determine how biogas and biomethane can optimize the energy system in the short and long term for centralized heat supply. The findings confirm that biogas and biomethane are essential, dispatchable renewable resources capable of supporting scalable, low-carbon, and resilient district heating systems across Europe.

The use of alternative energy sources and fuels is one of the most important areas of modern energy policy, aimed both at improving the environment and saving traditional fuel and energy resources. The meaning of the process of ecological and energy optimisation isn’t the replacement of one energy source with another, but economic and industrial transformation, decarbonisation, and decentralisation. Russian aggression caused unprecedented destruction of Ukraine’s fuel and energy infrastructure, which created a threat to the reliability of providing end consumers with natural gas – the main organic energy carrier capable of fully satisfying the state’s own needs. Agricultural waste and solid waste landfills can, under certain conditions, be transformed from environmental pollution into renewable energy sources with the generation of biogas. Its main components are methane and carbon dioxide. Biogas utilisation will simultaneously solve environmental problems associated with "thermal" environmental pollution. The results of the analysis of the European Green Deal strategy and global pricing of carbon dioxide emissions show the need to increase tax obligations in Ukraine for greenhouse gas emissions into the atmosphere to achieve the goals of limiting the increase in global environmental temperature to 1.5-2 ˚C. The article substantiates the possibility of full or partial replacement of natural gas with biomethane obtained from the utilisation of agro-industrial waste, household waste, etc. to meet the needs of the housing and communal services of Ukraine. A comparison of the physicochemical parameters of traditional natural gas and biomethane with the requirements of current regulatory documents has been made. The areas of application of biomethane in gaseous and liquefied states have been determined. The design solutions of technological installations for autonomous gas supply systems have been substantiated.

West Nusa Tenggara is a region prone to natural disasters, requiring strategies to strengthen food security as part of efforts to build community resilience. One potential alternative is mushroom cultivation based on simple technology. This community service activity aims to introduce and implement a technologically advanced mushroom cultivation model to support food security and disaster resilience in Sembalun Bumbung Village, East Lombok. The method used was participatory training with a learning-by-doing approach, involving the local community in all stages of mushroom cultivation, from media preparation and sensor-based environmental control to harvesting and post-harvest. The results of the activity showed that most participants initially lacked knowledge of mushroom cultivation, but after the training, there was an increase in interest and understanding of the economic and consumption benefits of mushroom cultivation. The implementation of mushroom houses with technology to monitor temperature, humidity, lighting, and biogas utilization was deemed effective and easily adopted by the community. Technologically advanced mushroom cultivation has the potential to become an adaptive and sustainable local food source, thus supporting food security and community resilience in the face of natural disasters.

Background: Indonesia faces substantial challenges in waste management, as most organic waste remains untreated. A similar situation occurs in Kendari City, which generates approximately 253 tons of waste per day, the majority of which consists of organic materials. This condition reflects the untapped potential of renewable energy derived from organic waste, thereby necessitating the development of an effective system to address these issues comprehensively. Methods: This study employed a descriptive research method with a case study approach. The data analyzed encompassed the volume and composition of organic waste in Kendari City. The findings served as the foundation for designing a Smart Biogas system integrated with the Internet of Things (IoT). The system incorporates sensors to monitor temperature, pressure, and methane concentration in real time and is connected to an application that enables remote monitoring and control. Findings: The study revealed that the potential biogas production from organic waste in Kendari City could reach approximately 5,650 m³ per day. This volume demonstrates significant potential to meet a portion of the local energy demand. By adopting a communal-based system design, the utilization of biogas can be optimized, particularly to support energy needs at the sub-district level. Conclusion: The results indicate that the implementation of the Smart Biogas system can not only reduce the volume of organic waste but also provide a sustainable energy independence solution. Novelty/Originality of this article: The novelty of this research lies in the development of a Smart Biogas system integrated with IoT technology, specifically designed for communal-scale applications. The system enables real-time monitoring of the fermentation process through temperature, pressure, and methane sensors, with remote access facilitated by an integrated application. This approach ensures that organic waste is not only effectively managed but also converted into renewable energy, thereby supporting local energy independence.

The increasing demand for sustainable energy solutions in rural areas has prompted the utilization of biogas and bio-slurry as alternative resources. This study aims to evaluate the economic feasibility of household-level biogas systems by integrating Cost-Benefit Analysis (CBA), Net Present Value (NPV), Benefit-Cost Ratio (BCR), and Undiscounted Payback Period (UPBP), complemented with sensitivity analysis. Primary data were collected from 16 households operating biogas systems, while secondary data supported the estimation of cost and benefit components. Results show that biogas adoption provides positive economic returns, with average NPV reaching Rp 12,749,000, BCR above 1.0, and UPBP within four years, indicating financial viability. Sensitivity analysis reveals that variations in LPG prices and livestock numbers significantly affect economic outcomes, demonstrating the importance of market and production factors in ensuring project sustainability. The findings conclude that household biogas systems are economically feasible and resilient under certain conditions. Future studies are suggested to expand the scope by incorporating environmental and social benefits, as well as exploring scalability at the community level.

Abstract Separation of methane (CH 4 ) and carbon dioxide (CO 2 ) is of significant industrial interest for the utilization of biogas, landfill gas and natural gas. While the state‐of‐the‐art membranes are CO 2 ‐selective, CH 4 ‐selective membranes remain elusive, with potential applications in the recovery and purification of methane‐rich gases such as biogas and landfill gas. Herein, we report a molybdenum‐oxygen (Mo─O) functionalized MFI‐type zeolite membrane for inverse CH 4 /CO 2 gas separation. A pure‐silica MFI‐type zeolite membrane is first seeded grown on an alumina support and subsequently functionalized via facile impregnation and calcination of sodium molybdate. The as‐prepared membrane features uniform pores (0.5 nm) and ultrasmall Mo─O clusters (1.6 nm). The Mo─O/MFI membrane selectively permeates CH 4 over CO 2 , achieving an unprecedented CH 4 /CO 2 separation factor of 11.8 alongside a high CH 4 permeance of 2.1 × 10 −8 mol s −1 m −2 Pa −1 . Experimental measurements and theoretical calculations reveal that CH 4 preferentially adsorbs onto Mo─O clusters via hydrogen bond and diffuses rapidly through MFI zeolite pores. This study represents the first demonstration of porous membranes enabling inverse CH 4 /CO 2 separation and offers guidance for the design of next‐generation CH 4 ‐selective membranes.

Separation of methane (CH4) and carbon dioxide (CO2) is of significant industrial interest for the utilization of biogas, landfill gas and natural gas. While the state-of-the-art membranes are CO2-selective, CH4-selective membranes remain elusive, with potential applications in the recovery and purification of methane-rich gases such as biogas and landfill gas. Herein, we report a molybdenum-oxygen (Mo─O) functionalized MFI-type zeolite membrane for inverse CH4/CO2 gas separation. A pure-silica MFI-type zeolite membrane is first seeded grown on an alumina support and subsequently functionalized via facile impregnation and calcination of sodium molybdate. The as-prepared membrane features uniform pores (0.5nm) and ultrasmall Mo─O clusters (1.6nm). The Mo─O/MFI membrane selectively permeates CH4 over CO2, achieving an unprecedented CH4/CO2 separation factor of 11.8 alongside a high CH4 permeance of 2.1×10-8mol s-1 m-2 Pa-1. Experimental measurements and theoretical calculations reveal that CH4 preferentially adsorbs onto Mo─O clusters via hydrogen bond and diffuses rapidly through MFI zeolite pores. This study represents the first demonstration of porous membranes enabling inverse CH4/CO2 separation and offers guidance for the design of next-generation CH4-selective membranes.

From agro-waste to biofuel: a critical review on biogas production, upgrading, and utilization in internal combustion engines in the Brazilian agroindustry

Abstract Biogas, generated through the anaerobic digestion of organic matter, is an attractive renewable energy source due to its continuous production and utilisation cycle. Rising concerns about the environmental impact of fossil fuel-derived energy have sparked interest in developing sustainable energy alternatives. Consequently, considerable research efforts have been directed towards biogas valorisation, particularly its main component, methane (CH 4 ). This is achieved by converting raw or upgraded biogas into high-value products, such as Zeolite-templated carbons (ZTCs), and concurrently producing cleaner hydrogen gas. ZTCs are highly ordered porous structures that exhibit high surface areas, uniform pore size distributions, and large pore volumes, rendering them attractive for various applications. These applications include gas storage, CO 2 capture, supercapacitors and batteries. In this study, we focused on the utilisation of simulated biogas (CH 4 and CO 2 mixture) and pure CH 4 (in this case, simulated ‘biomethane’) for the synthesis of zeolite-templated carbons (ZTCS). When CH 4 was utilised on both the one-step and two-step processes, the obtained ZTCs had higher surface area and hydrogen (H 2 ) adsorption. The highest surface area obtained was 2974 m 2 /g, while the best H 2 storage capacity, at 1 bar, was 2.77 wt%. Structural (XRD) and morphological (SEM and TEM) characterisations were found to be indistinguishable from those of the samples obtained when fossil-derived ethylene was used as a carbon source. Unfortunately, ZTCs were not obtained when simulated biogas was used as a carbon source, due to the zeolite having a greater affinity towards CO 2 than CH 4 , primarily because of the large quadrupole moment of CO 2 . This study has demonstrated that a sustainable source of carbonaceous feedstock, such as biogas-derived ‘biomethane’, can be converted into value-added products (ZTCs), thereby creating additional economic opportunities for industries within the biogas sector.

Antibiotic resistance genes (ARGs) and microbial communities in pig and cow dung from rural China were systematically profiled using high-throughput quantitative PCR arrays and 16S rDNA amplicon sequencing to assess their environmental dissemination and public health risks. The abundance and diversity of ARGs were markedly higher in pig dung than in cow dung. A total of 56 ARGs were enriched in pig dung, including β-lactamase genes (blaCMY, blaCTX-M) and macrolide resistance genes (ermB, ermF), along with several genes related to aminoglycoside and macrolide-lincosamide-streptogramin B resistance. In contrast, only eight ARGs were enriched in cow dung. Microbial community analysis revealed that cow dung was dominated by UCG-005, UCG-010, Methanocorpusculum, and Fibrobacter, taxa typically associated with ruminant digestion. In pig dung, Ignatzschineria, Lactobacillus, Pseudomonas, Streptococcus, Treponema, and conditional pathogens such as Escherichia coli and Leptospira were significantly enriched, indicating higher pathogen-related risks. Functional prediction identified 26 KEGG level-2 and 136 level-3 pathways, showing stronger xenobiotic degradation and amino acid metabolism in pig dung, whereas cow dung was enriched in energy metabolism and chemotaxis pathways. Moreover, the higher abundance of mobile genetic elements (e.g., intI1 and IS613) in pig dung suggests a greater potential for horizontal ARG transfer. Integrating ARG, microbial, and pathogen data reveals that pig dung acts as a composite source of "ARG-pathogen" contamination with enhanced transmission potential. These findings provide localized, data-driven evidence for developing safer livestock waste management practices, such as composting and biogas utilization, and contribute to antibiotic resistance mitigation strategies in rural China.