Search Results (2,680)

Biogas slurry with rich nutrients could be applied as fertilizer to improve nitrogen absorption and soil structure. Arbuscular mycorrhizal fungi (AMF) are beneficial soil microorganisms that establish mutualistic relationships with the plant roots. The purpose of this study was to study the effects of AMF and biogas slurry treatment on hybrid Pennisetum growth, soil chemical properties, and soil microorganisms. The results revealed that the biomass yield of hybrid Pennisetum was significantly increased after the application of biogas slurry, and it reached the peak values when the biogas slurry dosage was 900 t/hm², which were 13,216.67 kg/hm² and 13,733.33 kg/hm² in AMF− and AMF+ treatment groups, respectively. Moreover, biogas slurry treatment has a significant promoting effect on other agronomic traits related to biomass yield. As for soil chemical indicators, the contents of total nitrogen, nitrate nitrogen, ammonia nitrogen, and available phosphorus in the soil increased with the increase in biogas slurry application, while the soil organic matter was decreased. The addition of arbuscular mycorrhizal fungi significantly increased the species diversity of soil fungi with no biogas slurry application. Furthermore, when biogas slurry was applied, it had no significant effect on soil microbial diversity and composition, no matter the AMF+ or AMF− treatment. The research results can provide a reference for the long-term utilization of biogas slurry and it also can be used in the actual production of hybrid Pennisetum. Full article

Transitioning to low-carbon energy systems is crucial for sustainable development, particularly in oil-rich developing countries (ORDCs) that face intertwined economic and environmental challenges. This review uses the PRISMA methodology to systematically assess the current state and prospects of low-carbon thermal electricity generation and utilization technologies in ORDCs. The study emphasizes clean thermal technologies such as biogas, biofuels, biomass, hydrogen, and geothermal energy, focusing on solutions that are technically feasible, economically viable, and efficient in combustion processes. These nations face significant challenges, including heavy reliance on fossil fuels, transmission losses, and financial constraints, making energy diversification urgent. The global shift towards renewable energy and the need to mitigate climate change presents an opportunity to adopt low-carbon solutions that align with Sustainable Development Goals related to energy access, economic growth, and climate action. This review aims to (1) evaluate the current state of low-carbon thermal electricity technologies, (2) analyze the technical and economic challenges related to combustion processes and energy efficiency, and (3) provide recommendations for research and policy initiatives to advance the transition toward sustainable thermal energy systems in ORDCs. The review highlights practical approaches for diversifying energy sources in these nations, focusing on overcoming existing barriers and supporting the implementation of clean thermal technologies. Full article

In this study, the effect of awareness of renewable energy sources on sustainable production in dairy farming was determined. One hundred thirty-six surveys were conducted in the research area. Multiple linear regression analysis was used to determine the effect of awareness of renewable energy resources of dairy cattle farms on sustainable production. According to the results of the analysis, the number of animals, land assets, and age of farmers were found to be statistically significant at a 5% significance level. Awareness of renewable energy sources, environmental factors, and economic factors were found to be significant at a 10% significance level. Therefore, biogas should be converted into electricity. In order to provide waste management, organization should be ensured, and animal waste collection centers should be established. Full article

Circular economy, clean technologies, and renewable energy are key to climate protection and modern environmental technology. Recovering water and valuable minerals from the liquid fraction of digestate is in line with this strategy. Digestate, a byproduct of anaerobic methane fermentation in biogas plants, is a potential source of water, minerals for fertilizers, and energy rather than waste. This study examined digestate from municipal and agricultural biogas plants and highlights the need for research on both due to their differences. The use of membrane techniques for water recovery from liquid digestate offers an innovative alternative to conventional methods. This study used standalone membrane filtration and an integrated system to produce water suitable for agricultural use. Ceramic membranes with cut-offs of 1, 5, 15, and 50 kDa and polymeric membranes of polyethersulfone and regenerated cellulose with cut-offs of 10 and 30 kDa were tested. The results showed that the membrane material significantly affects the transport and separation properties. Higher cut-off values increased permeate flux across all membranes. Ceramic membranes were more susceptible to fouling in standalone ultrafiltration, but were more effective in purifying digestate than polymeric membranes. The best results were obtained with a ceramic membrane with a 1 kDa cut-off (for example, for the integrated process and the municipal digestate, the retention rates of COD, BOD₅ and DOC were 69%, 62%, and 75%, respectively). Full article

In this entry, the possibility of the implementation of a biorefinery based on multiple raw materials (from agricultural wastes, vegetable oils, etc.) is covered, pointing out the available technology to interconnect different processes so that the atom economy of the process is as high as possible, reducing the environmental impact and improving the efficiency of the energy or products obtained. For this purpose, this model is based on previous works published in the literature. The role of biorefineries is becoming more and more important in the current environmental scenario, as there is a global concern about different environmental issues such as climate change due to GHG emissions, among others. In this sense, a biorefinery presents several advantages such as the use of natural raw materials or wastes, with high atom economy values (that is, all the products are valorized and not released to the environment). As a consequence, the concept of a biorefinery perfectly fits with the Sustainable Development Goals, contributing to the sustainable growth of different regions or countries, regardless of their stage of development. The aim of this entry is the proposal of a biorefinery based on multiple raw materials, using different technologies such as transesterification to produce both biodiesel and biolubricants, steam reforming to produce hydrogen from glycerol or biogas, hydrothermal carbonization of sewage sludge to produce hydrochar, etc. As a result, these technologies have potential for the possible implementation of this biorefinery at the industrial scale, with high conversion and efficiency for most processes included in this biorefinery. However, there are some challenges like the requirement of the further technological development of certain processes. In conclusion, the proposed biorefinery offers a wide range of possibilities to enhance the production of energy and materials (hydrogen, biodiesel, biolubricants, different biofuels, hydrochar, etc.) through green technologies, being an alternative for petrol-based refineries. Full article

Driven by environmental and economic considerations, this study explores the viability of utilizing coconut juice residues (CJRs), a byproduct from coconut milk production, as a carbon source for bacterial cellulose (BC) synthesis in the form of a versatile bio-membrane. This work investigates the use of optimization modeling as a tool to find the optimal conditions for BC cultivation in consideration of waste minimization and resource sustainability. Optimization efforts focused on three parameters, including pH (4–6), cultivation temperature (20–30 °C), and time (6–10 days) using Design Expert (DE) V.13. The maximum yield of 9.31% (g/g) was achieved when the cultivation took place at the optimal conditions (pH 6, 30 °C, and 8 days). This approach aligns with circular economy principles, contributing to sustainable resource management and environmental impact reduction. The experimental and predicted optimal conditions from DE V.13 were in good agreement, validating the study’s outcomes. The predictive model gave the correlations of the optimal conditions in response to the highest yield and maximum eco-efficiency. The use of prediction modeling resulted in a useful tool for forecasting and obtaining guidelines that can assist other researchers in calculating optimal conditions for a desired yield. Acetylation of the BC resulted in cellulose acetate (CA) membranes. The CA membrane exhibited the potential to separate CO₂ from a CH₄/CO₂ mixed gas with a CO₂ selectivity of 1.315 in a membrane separation. The promising gas separation results could be further explored to be utilized in biogas purification applications. Full article

The energy sector is essential in the transition to a more sustainable future, and renewable energies will play a key role in achieving this. It is also a sector in which the circular economy presents an opportunity for the utilisation of other resources and residual energy flows. This study examines the environmental and social performance of innovative energy technologies (which contribute to the circularity of resources) implemented in a demonstrator site in Luleå (Sweden). The demo-site collected excess heat from a data centre to cogenerate energy, combining the waste heat with fuel cells that use biogas derived from waste, meeting part of its electrical demand and supplying thermal energy to an existing district heating network. Following a cradle-to-gate approach, an environmental and a social life cycle assessment were developed to compare two scenarios: a baseline scenario reflecting current energy supply methods and the WEDISTRICT scenario, which considers the application of different renewable and circular technologies. The findings indicate that transitioning to renewable energy sources significantly reduces environmental impacts in seven of the eight assessed impact categories. Specifically, the study showed a 48% reduction in climate change impact per kWh generated. Additionally, the WEDISTRICT scenario, accounting for avoided burdens, prevented 0.21 kg CO₂ eq per kWh auto-consumed. From the social perspective, the WEDISTRICT scenario demonstrated improvement in employment conditions within the worker and local community categories, product satisfaction within the society category, and fair competition within the value chain category. Projects like WEDISTRICT demonstrate the circularity options of the energy sector, the utilisation of resources and residual energy flows, and that these lead to environmental and social improvements throughout the entire life cycle, not just during the operation phase. Full article

Wastewater treatment must be proactive and sustainable to facilitate an increase in the circularity of water. Therefore, the current approach, based on a linear cycle, must be replaced with a circular economy concept that implements strategies to address the different byproducts in the wastewater treatment sector. In recent years, Nuevo León, Mexico, has encountered high water stress levels, with its main water bodies presenting their lowest levels ever recorded. This study was focused on the wastewater treatment plant Monterrey, which treats the largest volume at the state level. Throughout its operation process, it generates different potential byproducts that are yet to be harnessed to fully. This study developed three proposals using a circular economy approach: the treatment of water for the industrial sector, the use of residual sludge as an organic fertilizer, and the cogeneration of energy from biogas. These proposals can potentially generate benefits regarding the three pillars of sustainability, yielding a closed cycle in the wastewater treatment sector at the national level. Full article

Energy policies around the world are increasingly highlighting the importance of hydrogen in the evolving energy landscape. In this regard, the use of hydrogen to produce biomethanol not only plays an essential role in the chemical industry but also holds great promise as an alternative fuel for global shipping. This study evaluates a system for generating biomethanol and biomethane based on anaerobic digestion, biogas upgrading, methanol synthesis unit, and high-temperature electrolysis. Thermal integration is implemented to enhance efficiency by linking the oxy-fuel gas turbine unit. The integrated system performance is evaluated through thermodynamic modeling, and Aspen Plus V12.1 is employed for the analysis. Our findings show that the primary power consumers are the Solid Oxide Electrolysis Cell (SOEC) and Methanol Synthesis Unit (MSU), with the SOEC system consuming 824 kW of power and the MSU consuming 129.5 kW of power, corresponding to a production scale of 23.2 kg/h of hydrogen and 269.54 kg/h of biomethanol, respectively. The overall energy efficiency is calculated at 58.09%, considering a production output of 188 kg/h of biomethane and 269 kg/h of biomethanol. The amount of carbon dioxide emitted per biofuel production is equal to 0.017, and the proposed system can be considered a low-carbon emission system. Key findings include significant enhancements in biomethanol capacity and energy efficiency with higher temperatures in the methanol reactor. Full article

The production of huge amounts of biogas slurry during livestock breeding has resulted in pressing environmental issues. Although paddy fields can be potential sinks for the disposal of biogas slurry, the impacts of biogas slurry on rice production, grain quality, and relevant environmental risks in the Yangtze Delta region remain unclear. Herein, we conducted a field trial from 2021 to 2023 which involved different gradients of biogas slurry utilization, including CK (no fertilizer), CN (100% chemical nitrogen (N) of 240 kg ha⁻¹), NBS (biogas slurry replacing 50% chemical N), BS1 (replacing 100% chemical N), BS1.5 (replacing 150% chemical N), and BS2 (replacing 200% chemical N). The results showed that there were no significant differences in average rice yields between CN, NBS, BS1.5, and BS2 over the three-year study period, with an average yield of 8283 kg ha⁻¹, and the average yields of BS1 and CK were 7815 kg ha⁻¹ and 6236 kg ha⁻¹, respectively. However, heavy utilization of biogas slurry (BS1.5 and BS2) not only significantly reduced the rice seed-setting rate, the 1000-grain weight, and the processing quality, but also significantly increased the protein, amylose, Cu, and Zn content in rice grains; additionally, higher N losses occurred via surface water and increased NH₃ volatilization was observed, finally resulting in lower nitrogen-use efficiency. Meanwhile, moderate utilization of biogas slurry (NBS and BS1) led to better rice quality and nitrogen-use efficiency, lower potential food safety risk, and N loss. Further, compared to BS1, NBS showed higher yield, harvest index, processing quality, gel consistency, palatability scores, and nitrogen-use efficiency, but lower N losses were present. Overall, the NBS treatment balanced the agronomic benefits and environmental risks in the Yangtze River Delta region. In the future, more attention should be paid to food safety and environmental risks when using biogas slurry. Full article

Wheat straw (WS) is a promising substrate for biogas production by anaerobic digestion (AD) due to its high carbohydrate content. An estimated 0.603 million t yr⁻¹ of WS are generated from wheat production systems in South Africa. This is equivalent to an energy potential of 11 PJ. Despite this, WS is still undervalued as a bioenergy resource in South Africa due to its structural complexity and low nitrogen content. WS disposal methods, such as use in livestock bedding, burning and burying into the soil, inter alia, are not sustainable and may contribute to global warming and climate change. The commercialization of the AD of WS needs to be further developed and promoted. Pre-treatment (i.e., physical, chemical, biological and hybrid methods) and anaerobic co-digestion (AcoD) are novel strategies that can support the conversion of WS into biogas and other value-added products. Current and future research should focus on optimizing pre-treatment and AcoD conditions towards industrialization of WS into valuable products. This paper focuses on the potential use of WS for biogas production in South Africa. The aim is to create information that will promote research and development, and encourage policy makers and stakeholders to participate and invest in WS biogas technology. Were WS biogas technology fully adopted, we believe that it would alleviate energy insecurity and environmental degradation, and sustain the livelihoods of citizens in South Africa. Full article

The utilization of biomass ash in sustainable agriculture and increasing its fertilizing efficiency by biological agents, potentially sequestering CO₂, have become important issues for the global economy. The aim of this paper was to investigate the effects of ash from sorghum (Sorghum bicolor L. Moench) and Jerusalem artichoke (Helianthus tuberosus L.) biomass, a biogas plant digestate, and a Spirodela polyrhiza extract, acting alone or synergistically, on soil fertility and the development, health and physiological properties of sorghum plants. The results show novel information concerning differences in the composition and impact of ash, depending on its origin, soil properties and sorghum plant development. Sorghum ash was more effective than that from Jerusalem artichoke. Ash used alone and preferably acting synergistically with the digestate and Spirodela polyrhiza extract greatly increased soil fertility and the growth, biomass yield and health of sorghum plants. These improvements were associated with an increased chlorophyll content in leaves, better gas exchange (photosynthesis, transpiration, stomatal conductance), greater enzyme activity (acid and alkaline phosphatase, RNase, and total dehydrogenase), and a higher biomass energy value. The developed treatments improved environmental conditions by replacing synthetic fertilizers, increasing the sequestration of CO₂, solving the ash storage problem, reducing the need for pesticides, and enabling a closed circulation of nutrients between plant and soil, maintaining high soil fertility. Full article

The accumulation of organic dyes and heavy metals (HMs) in sewage sludge (SS) after wastewater treatment is a significant problem due to the non-degradable nature of these pollutants. Moreover, the simultaneous removal of HMs and dyes in the complex process of SS treatment, such as anaerobic digestion (AD), has become attractive. HMs and dyes present in SS can have a detrimental effect on anaerobic digesters. These pollutants not only inhibit the production of methane, which is crucial for biogas generation, but also affect the stability of AD treatment, which can result in failure or inadequate performance of the AD process. This review highlights a novel method of removing HMs and dyes from the AD process of SS through the use of biochar modified with polyvinyl alcohol (PVA) and chitosan (CTS). The applications of conventional biochar have been limited due to poor adsorption capacity. However, modification using PVA/CTS composites enhances properties such as surface functional groups, adsorption capacity, porosity, surface area selectivity, and stability. Furthermore, this modified version can function as an additive in AD of SS treatment to boost biogas production, which is a viable source for heat generation or electricity supply. In addition, the digestates can be further processed through plasma pyrolysis for the removal of HMs and dyes bound to the modified biochar. Plasma pyrolysis generates two major products: syngas and slag. The syngas produced can then be used as a source of hydrogen, heat, and electricity, while the slag can potentially be reused as an AD additive or as a biofertilizer in the agricultural sector. Additionally, this study addresses the challenges associated with this integration and biochar modifications, and offers an outlook on understanding the interactions between the modified biochar properties, microbial dynamics, and the presence of micropollutants to ensure the economic viability and scalability of this technology. This comprehensive review provides insights into the potential of PVA/CTS-modified biochar as an effective additive in AD systems, offering a sustainable approach to SS treatment and valuable resource recovery. Full article

The agricultural production of maize (Zea mays L.) increases the risk of water erosion. Perennial crops like cup plant (Silphium perfoliatum L.) offer a sustainable alternative to produce biomass for biogas plants. The assessment of soil conservation measures requires calibrated soil erosion models that spatially identify soil erosion processes. These support decision-making by farmers and policymakers. Input parameters for the physically based soil erosion model EROSION 3D for cup plant cultivation were established in a field study. Rainfall simulation experiments were conducted to determine the model input parameter’s skinfactor and surface roughness. The results showed a reduction of soil erosion and higher infiltration rates for cup plant resulting in higher skinfactors of 11.5 in June and 0.75 post-harvest (cup plant) compared to 1.2 in June and 0.21 post-harvest (maize). With the extended parameter catalogue of EROSION 3D for cup plant cultivation model simulations were conducted for a rainfall event in June (64 mm). The sediment budget would have been reduced by 92.6% through the growth of cup plant in comparison to conventionally grown maize. Perennial cup plant can, therefore, contribute to achieving the targets outlined in the European Green Deal by reducing soil erosion and enhancing soil health. Full article

The presented research addresses a problem occurring in a biogas plant, which we know plays an important role in sustainable development. The sludge deposited on the walls of the digester’s heat exchanger impairs heat transfer to the substrate. It leads to a temperature drop inside the biogas plant and threatens its correct operation. The thickness of the sludge layer cannot be directly measured when the plant is operating. Therefore, the aim of this work was to develop and then validate a method for estimating, based on the operating parameters of the exchanger, the thickness of the sludge layer and to give theoretical foundations for designing an automatic sludge monitoring system. Two mathematical models (and methods) were developed: one- and two-dimensional. The former model was solved analytically while the latter by the Trefftz method. The numerical results from these two approaches showed very good agreement with each other and with the actual measurement taken directly after removing the substrate from the fermentation chamber. According to the calculation results, the growth of the sludge layer was linear with time, and its rate was 0.0064 mm per day. Finally, a schematic diagram of an intended sludge monitoring system was proposed. It could optimize biogas plant operation and thus become a step towards more sustainable energy production. Full article