Industrial waste streams particularly spent hydraulic oil represent an untapped opportunity to improve the environmental performance of manufacturing systems. As industries face pressure to transition toward cleaner and more circular operations, measuring the ecological impact of recovery technologies becomes essential. Literature reports that conventional disposal methods for spent oil are often energy-intensive and associated with substantial greenhouse gas emissions. This study evaluates the energy demands and environmental impacts of recovering spent hydraulic oil through a life cycle assessment (LCA) framework. The recovery process involved multi-stage regeneration, including filtration, dewatering, and vacuum treatment. It consumed 9.45 kWh of electricity and 8.06 L of diesel per batch of 11,500 L of spent hydraulic oil. Life cycle assessment results indicate a global warming potential of 293.71 kg CO2-eq, fossil resource scarcity of 96.78 kg oil-eq, and water consumption of 1.99 m3 per functional unit. Toxicity-related impacts were also observed including freshwater ecotoxicity of 13,623.79 kg 1,4-DCB-eq and human carcinogenic toxicity of 4654.89 kg 1,4-DCB-eq. Physicochemical analysis confirmed the presence of hazardous components in the waste oil, which supports the need for safe recovery pathways. Life cycle results also highlighted critical environmental burdens tied to fossil fuel use and emissions from transportation and electricity production. The findings suggest that recovery of spent hydraulic oil may offer comparatively lower environmental burdens relative to literature-reported disposal pathways, based on qualitative comparison under the stated assumptions and system boundaries. These results provide baseline reference data for evaluating process performance and informing sustainability-oriented industrial decision-making.
Biofertilizers have emerged as promising inputs for sustainable crop production because they can enhance ecosystem services while maintaining crop productivity. However, quantitative evidence on the joint effects of biofertilizers on productivity and ecosystem services remains fragmented. This study quantifies the effects of biofertilizer application on crop productivity and selected ecosystem services in Indian agriculture and examines potential synergies or trade-offs between these outcomes while also estimating the economic value of associated ecosystem services. This study conducted a meta-analysis based on 2031 paired observations from 135 peer-reviewed field studies. Effect sizes were calculated using the natural logarithm of the response ratio (lnRR), and mixed-effects models were applied to estimate overall and subgroup responses across biofertilizer types, crop categories, soil types, and agro-climatic zones; heterogeneity was assessed using the I2 statistic and Q-test (p < 0.05). Biofertilizer application increased crop yield by 14.43
This study investigates the thermal conversion of chicken manure and onion peels into biochars with tailored properties for CO2 adsorption. The process was conducted at 700, 800 and 900 °C under inert atmosphere. The resulting biochars were characterised using Fourier-Transform Infrared Spectroscopy, X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy (XPS), Raman spectroscopy, nitrogen sorption analysis, and CO2 adsorption measurements. Increasing pyrolysis temperature enhanced carbonisation, reduced heteroatom content, and promoted pore development, particularly in onion peels-derived in biochars. Nitrogen sorption analysis revealed the development of mesoporous and microporous structures, with the biochar derived from onion peels at 900 °C exhibiting the highest specific surface area (109.8 m2/g). However, the CO2 adsorption capacity showed divergent trends: it correlated with surface area development in chicken manure biochars, whereas onion-peel-derived biochars showed a non-monotonic relationship, with the 700 °C sample having the highest adsorption capacity (26.6 cm3/g at 100 kPa). In contrast, chicken manure biochars exhibited increased CO2 adsorption capacity with increasing pyrolysis temperature, which was associated with the development of micropores and the presence of calcium-rich mineral phases, identified by XRD and XRF analyses. Raman and XPS analyses indicated progressive structural ordering and deoxygenation with increasing pyrolysis temperature. The results demonstrate that CO2 adsorption in biochars derived from onion peels is mainly governed by pore-filling mechanisms, while mineral-assisted interactions significantly contribute to CO2 capture in chicken manure biochars.
Traditional grid-connected municipal water pumping stations are highly susceptible to primary grid instability and electricity price volatility, a vulnerability particularly emphasized in remote or isolated locations. This study investigates the integration of solar photovoltaic (PV) systems and battery energy storage systems (BESS) within a microgrid architecture to enhance energy efficiency and autonomy for a critical island municipal water pumping facility. Utilizing long-term simulation scenarios, a dynamic model was developed incorporating historical water demand data, solar irradiance profiles, and commercial energy storage parameters to evaluate rule-based energy management strategies aimed at load shifting and price arbitrage. The simulation results demonstrate a clear techno-economic trade-off between initial investments and long-term financial resilience. A minimal microgrid configuration (with 500 kWh BESS, 1700 m2 solar PV surface, and peak DC power output of 340 kW) achieves the fastest localized return on investment (ROI) at 7.6 years primarily due to minimized initial costs, but it remains incapable of complete load shifting. In contrast, expanding the microgrid toward a high-capacity system configuration (with 2000 kWh BESS, 4100 m2 solar PV surface area, and peak DC power output of 820 kW) results in the ROI period being extended up to 13.7 years. However, it also significantly maximizes long-term profitability, and virtually eliminates high-tariff reliance during low water demand. Long-term microgrid component aging assessment indicates systemic sustainability with the BESS maintaining state-of-health above 48
The development of innovation districts imposes significant challenges on sustainable territorial planning, particularly with respect to mobility and transportation infrastructure. This study evaluates travel demand scenarios and traffic operational performance within the International Hub for Sustainable Development (HIDS), an innovation district currently under implementation in Campinas, Brazil. The analysis focuses on the Fazenda Argentina area, owned by the University of Campinas, which corresponds to the first implementation phase of the district and currently lacks consolidated urban occupation. Travel demand was estimated based on trip generation parameters derived from the literature and applied as input data for traffic microsimulations conducted using the Aimsun Next software. Multiple traffic flow scenarios were simulated to assess roadway capacity, Level of Service, and the operational performance of the main access corridors under different through traffic and roadway operating conditions. In addition to private vehicle demand, scenarios incorporating public transportation and active mobility were analyzed to evaluate their potential to reduce traffic volumes and improve operational conditions. The results identify critical demand thresholds that may compromise the performance of the roadway infrastructure and highlight the importance of sustainable mobility strategies in maintaining adequate service levels without major infrastructure expansions. In emerging and data-scarce urban contexts, exploratory scenario-based studies may also play an important role in supporting evidence-informed planning strategies and public policy decision-making during the early stages of large-scale urban developments. Thus, the study contributes to the literature by proposing a scenario-based approach to support mobility and infrastructure planning in innovation districts embedded in emerging Knowledge-Based Urban Development (KBUD) contexts, particularly in situations with limited availability of operational data.
In recent years, hybrid and electrical cars have been gradually replaced by internal combustion (IC) engines. However, it seems certain that internal combustion engines will continue to dominate the market for the foreseeable future due to the problems with these cars’ battery and charging systems. Therefore, to improve internal combustion engine efficiency and reduce their emissions, it is imperative that they be compatible with other energy sources. This research employed a single-cylinder, four-stroke direct injection diesel engine with electronically regulated exhaust emissions. Diesel (D100), waste plastic oil (P), and hydrogen (H2) were among the fuel types used. The study was carried out with a maximum load and a fixed engine speed of 1500 rpm throughout a range of compression ratios (CR15–19). We looked at how 90
The electroplating tin industry discharges tin-containing electroplating wastewater, which is often treated by Fe/Al flocculant to generate waste sludge. For the resource recovery of the sludge, recycling Sn from the sludge without any secondary waste is of great significance. Herein, a laboratory-scale closed-loop process was developed to recycle Sn from sludge. This sequentially involves hydrochloric acid leaching, aluminum plate cementation for high-purity sponge tin extraction, and upcycling the remaining Fe/Al-rich raffinate into active wastewater flocculants. The sludge contained 8.7
The construction industry often encounters significant environmental challenges, driven by rising waste management demands and its substantial contribution to carbon emissions. Concrete waste accounts for a significant share of global construction sector waste, underscoring the urgent need for effective resource recovery methods. Concrete waste recycling (CWR) is increasingly recognized as a circular-economy strategy to reduce waste and minimize environmental impact. However, despite its perceived advantages, widespread adoption remains stifled by systemic barriers. While previous studies have broadly addressed construction waste management, comprehensive reviews focusing specifically on CWR barriers and critical success factors (CSFs) remain limited. To address this gap, this study systematically reviews the barriers and CSFs influencing CWR implementation in the built environment. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach, 65 scholarly publications were retained for analysis. The review identified 30 barriers across six domains, with the most dominant being high investment costs, poor quality and limited applications of recycled concrete products, lack of comprehensive regulations, limited advanced recycling technologies, and insufficient recycling facilities. The CSFs for CWR implementation encompass legal and regulatory, economic and market, infrastructure and technology, and knowledge and education drivers. The study integrates these findings into a conceptual framework that defines CWR's systemic drivers, barriers, and stakeholders for effective implementation. It emphasizes that overcoming CWR barriers requires implementing relevant CSFs, supported by coordinated stakeholder action across the concrete recycling value chain. The findings provide practical insights for practitioners and policymakers to enhance CWR and achieve circular economy objectives in the built environment.
The maritime sector urgently needs to meet International Maritime Organization (IMO) decarbonization targets. Amine-based onboard carbon capture (OCC) stands out as an essential transitional technology. However, existing studies have not addressed the inconsistency between fragmented performance evaluation and the demand for comprehensive solvent selection criteria for maritime applications. Specifically, existing studies lack a life cycle-coupled environmental–energy–economic (3E) assessment that integrates multidimensional environmental quantification, full-process energy accounting, and external cost internalization for amine-based OCC systems. In this study, we constructed a holistic life cycle 3E evaluation framework, and conducted a head-to-head comparison of three representative amine-based OCC systems (MEA, PZ, MDEA/PZ) for the first time. We quantified 18 environmental impact indicators using the ReCiPe midpoint approach, mapped the full life cycle energy flows including direct operational energy and indirect embodied energy, and developed a full life cycle cost model incorporating external environmental damage costs. The results demonstrate that PZ-based OCC system shows favorable performance across environmental, energy, and economic dimensions: It reduces the global warming potential to 437.83 kg CO2 eq per ton of captured CO2, cuts the total life cycle energy consumption to 7.28 GJ per ton of CO2, and achieves the minimum levelized capture cost of 131.82 per ton of CO2. By contrast, the benchmark MEA system presents inferior applicability in maritime operational scenarios owing to excessive energy consumption and prominent environmental burden, and the MDEA/PZ blend merely serves as a suboptimal an alternative solution. This study addresses the research gap of holistic life cycle 3E assessment for amine-based OCC technologies, identifies PZ as a preferred solvent for maritime decarbonization applications, and provides both fundamental data and practical guidelines for the deployment of OCC technology to facilitate the achievement of IMO decarbonization targets.
Nearly half of the global food production is lost due to inefficiencies in post-harvest handling, processing, storage, and distribution, with fruit and vegetable waste representing an environmental and economic issue. This review synthesises recent literature on the integration of artificial intelligence (AI) and the circular economy (CE) approaches for fruit and vegetable waste (FVW) management. It explores how cutting-edge technology and environmentally friendly methods can mitigate FVW across the food value chain. The synthesis shows that AI-driven techniques, including computer vision, machine learning, and deep learning, support spoilage detection, intelligent sorting, demand forecasting and supply chain optimisation, while the CE framework enables valorisation of FVW into compost, bioplastics, and bioenergy. Building on these findings, an integrated conceptual framework is proposed linking AI-enabled monitoring, prediction, and decision-making with CE-based valorisation pathways. Unlike prior reviews that examine AI and CE separately in food waste contexts, this work provides a unified synthesis specific to FVW and critically compares AI approaches by strength, scalability, and deployment challenges. Overall, it demonstrates how the synergistic application of AI and CE principles can significantly reduce food loss, enhance resource efficiency, and support the transition towards resilient, low-waste and sustainable food systems, with direct implications for food security, environmental sustainability and socio-economic resilience.
This study evaluates solar-powered electrocoagulation (S-EC), using chemical coagulation (CC) as a comparative reference, for treating real P-rich fertilizer effluent with high acidity (pH 2.0 ± 0.1) and P concentration (970 ± 35 mg L−1). Current density, electrode surface-to-volume ratio ( S/V ), initial P concentration, and electrode material were optimized. Under optimal conditions (Al electrodes, j = 55.6 mA cm−2, S/V = 3.6 m−1, 120 min), S-EC achieved 96–97
Floating photovoltaic (FPV) systems have emerged as a promising solution to expand renewable energy capacity and reduce water losses and greenhouse gas emissions. However, existing sitting approaches often rely on subjectivity and make the results highly location-specific. To overcome these limitations, this study developed a multimodel data-driven framework for selecting FPV sites in artificial reservoirs. Extreme gradient boosting (XGBoost), light gradient boosting machine (LightGBM), and random forest (RF) were trained and optimized using Bayesian hyperparameter tuning to enhance predictive robustness and minimize overfitting. Finally, the probabilistic outputs of the best-performing model, XGBoost, were reclassified into five suitability levels to produce the final FPV suitability map. As a result of these processes, nine candidates were identified. The most suitable candidate site alone could generate 2.3 times the annual electricity consumption of Kırşehir Province and almost 9.4
With sunlight as an energy source, carbon-based products can be produced from atmospheric carbon without relying on fossil resources. Thus, one electricity- and two bio-based carbon dioxide utilization options are compared exemplarily for the provision of methanol. The energy requirements of each pathway and the included sub-steps are assessed based on theoretical and state-of-the-art efficiencies to allow for a fair comparison of the overall energy balance and to assess the energetic value of biomass. The results show that the investigated power-based pathway has a higher energy efficiency under ideal conditions (i.e., 23.5 kJ kJ_CH_3OH^ - 1 . under ideal conditions and 7.1 to 11.5 kJ kJ_CH_3OH^ - 1 . under present-day conditions). This work lays the foundation for further analyses of these pathways and their multifaceted benefits and drawbacks beyond purely energetic considerations.
The global consumption of vegetable oil has increased by 71 Business model configurations of centralized UCO supply chains
Decarbonizing the steel industry is essential for achieving global net-zero emissions and fostering sustainable industrial systems. This study investigates the potential of Power-to-X (PtX) technology to convert residual CO2 from steel manufacturing into methanol (MeOH), offering a pathway to industrial carbon circularity. The proposed PtX system integrates solid oxide electrolysis, using CO2 and water (H2O) to produce syngas as feedstock for methanol synthesis. The study also compares membrane- and chemical-based methods for capturing residual CO2. By leveraging renewable energy, this approach mitigates greenhouse gas emissions and enhances sustainability in steel and chemical production. Through a comparative analysis of three Canadian regional scenarios, this study quantifies the environmental and economic impacts of PtX deployment. Results show up to a 62.3
Reusable packaging can potentially lead to lower greenhouse gas (GHG) emissions through repeated use; however, it requires additional steps like collection and washing. In food delivery, quantitatively assessing whether emissions from these steps outweigh reuse benefits is crucial. This study compared the GHG emissions of single-use (PP/PET) and reusable (SST/PP) packaging within the food delivery sector of Seoul, utilizing the most recent localized empirical statistics updated through 2023, covering production, delivery, collection, washing, and disposal stages. The target reusable packaging, made of stainless steel and polypropylene, was selected to represent the average volume of a single meal portion in Korea’s delivery market, ensuring comparability with typical single-use packaging. Based on Korean food delivery trends, delivery distances were set to 1–5 km, with 300 reuse cycles assumed considering potential breakage. Baseline comparisons and mitigation scenario analyses were conducted. The results showed that single-use packaging consistently emitted less GHG at a 1 km delivery, with no break-even point reached. However, at 3 km and for four or more portions, an environmental break-even point occurred after 70 uses. Given the rising share of single-person households in Korea, excessively broad promotion of reusable items may lead to greenwashing by increasing the net environmental burden. Therefore, this study suggests a hybrid strategy focused on the optimization of delivery logistics and packaging. These findings provide a critical benchmark for environmental trade-offs in hyper-dense urban logistics, serving as a future scenario for other growing delivery markets.
Canada has a target of reaching net-zero emissions by 2050, while Prince Edward Island (PEI) aims to achieve this by 2040, which would make it the first province to reach the net-zero target. Transportation is the most significant contributor to PEI’s greenhouse gas (GHG) emissions, making the transition to electric vehicles a critical strategy to reduce GHG emissions in PEI. This study’s objective was to develop a spatial optimization framework that determines the number of EV station locations in PEI while predicting the emission reductions to 2040 under three scenarios: the replacement of all gasoline vehicles (Gasoline to EV), all diesel vehicles (Diesel to EV), and both with EVs (Both to EV) with adoption rates of 30
Circular agriculture offers a sustainable pathway to enhance resource-use efficiency and mitigate carbon emission intensity in food systems, particularly in resource-constrained hill agro-ecosystems. The present study evaluated seven different circular, semi-circular and linear farming models integrating white button mushroom cultivation with the French bean–potato cropping sequence under the temperate conditions of the Western Ghats, India. System productivity was quantified using potato equivalent yield. The environmental performance of the farming systems was evaluated through life cycle assessment to estimate carbon footprint, emission intensity and carbon efficiency across the seasons (2022–2024). Mushroom cultivation under ambient seasonal conditions achieved a mean biological efficiency of 16.41
The transition of electricity power systems toward circular models based on renewable energy is a fundamental requirement for achieving the sustainable development goals. Quantifying the development level of circular economy strategies and identifying structural imbalances in renewable systems through robust indicators are a decisive prerequisite for proposing effective and global solutions to the energy dilemma of the circular economy. This work proposes a comprehensive quantification of the current status of ten circular economy strategies across the life-cycle stages of renewable energy systems. The methodology develops and evaluates two indicators based on a Quantitative Systematic Review method and multi-criteria weighting tools. The analysis considers ten circular economy strategies and four criteria: technological maturity, costs, regulatory framework, and real-world applications. Results quantify that ‘Recycle’ and ‘Recover’ strategies achieve the lowest scores and are near their maximum development, unlike ‘Refuse’ and ‘Rethink’, which are far from their maximum development despite having lower energy demand. The findings confirm the predominance of end-of-life strategies, while use-phase strategies are the least developed, revealing systemic weaknesses in extending the operational lifespan of renewable systems. The degree of imbalance is quantified for each criterion, identifying the regulatory framework as the area with the most critical disparities. Based on these findings, effective measures to address the energy dilemma are identified. The behavior of these indicators provides a quantitative foundation that complements existing multi-criteria empirical studies in the scientific literature, establishing them as a robust tool for measuring progress toward a macrolevel circular economy within the context of renewable systems.
