Explainable AI-based optimization of facility operations for excessive NOx emission control: A case study of a solid refuse fuel combustion facility

Palm oil mill effluent (POME) remains a major environmental challenge in the palm-oil industry due to its high organic load, nutrient content, recalcitrant compounds, and methane emissions associated with conventional treatment and disposal. This review synthesizes two decades of scientific, technological, and policy developments to assess pathways for cleaner, resource-efficient POME management. Conventional treatment systems mainly open ponding—offer low-cost stabilization but can generate high greenhouse-gas emissions. Engineered biological reactors and membrane-based polishing units can achieve high organic-matter removal (COD and BOD removal often >80% in pilot- to full-scale treatment trains), although performance depends on influent strength and operating conditions. Nature-based solutions (NBS), including microalgae, floating macrophytes, and constructed wetlands, provide low-energy alternatives with strong nutrient removal and biomass valorization potential, though performance remains sensitive to hydraulic and climatic variability. Resource-recovery routes such as biogas, struvite precipitation, biochar production, polyhydroxyalkanoate formation, and single-cell protein generation highlight opportunities for circular-bioeconomy integration at the mill scale. Comparative policy analysis across major producer regions indicates persistent disparities in discharge limits, enforcement capacity, and methane-capture requirements, which influence technology adoption and sustainability certification. By integrating treatment efficiency, resource-recovery potential, technology readiness, and governance context within a structured decision framework, this review advances a systems-level roadmap for selecting and upgrading POME treatment pathways. Key research needs include improving NBS resilience, integrating digital monitoring and AI-based optimization, expanding techno-economic and life-cycle assessments, and harmonizing regulatory frameworks. Overall, this review identifies technical, ecological, economic, and governance strategies that can transform POME from an environmental liability into a low-carbon, resource-positive stream aligned with cleaner production objectives. • POME treatment remains a major bottleneck in sustainable palm oil processing • Anaerobic digestion with biogas recovery is the most mature POME valorization route • Hybrid systems improve effluent quality, energy recovery and operational stability • Nature-based solutions enable low-energy polishing but require resilience optimization

Extraction, composition, and stabilization strategies on mangosteen pericarp bioactive compounds for sustainable natural colorants and functional foods.

Towards carbon-neutral wastewater reclamation: Long-Term performance evolution and greenhouse gas emission analysis in a mega-scale reclaimed water plant.

Hybrid manufacturing/remanufacturing systems present a promising solution to achieving sustainable production by integrating remanufacturing strategies and reducing environmental impact. However, balancing the economic and environmental trade-offs in these systems, especially under the influence of random machine failures and greenhouse gas (GHG) emissions constraints, remains a critical challenge. This study proposes a dynamic Environmental Hedging Policy (DEHPP) tailored for failure-prone hybrid production systems operating under carbon tax regulations. The policy dynamically synchronises manufacturing and remanufacturing operations, switching priority between machines based on inventory thresholds, emission levels, and machine availability. The proposed control framework is derived using stochastic optimal control theory and validated through numerical resolution. The results show that the policy effectively minimises total costs, including inventory holding, backlog, production, and emissions costs. Sensitivity analyses reveal the impact of key parameters such as costs, failure and emission rates on the optimal parameters of the policy and system performance. A comparative evaluation against two adapted benchmark policies from the literature shows that DEHPP achieves up to 40% lower discounted total cost across wide variations in costs, failure, repair and emission rates. Managerial insights are provided to help decision-makers implement the policy in real-world scenarios, optimising production strategies and adhering to environmental regulations.

The key to green shipping lies in the transition of oil-fueled vessels, which account for 98.4% of the total fleet, to renewable and clean fuel types. This shift is crucial for achieving the greenhouse gas (GHG) emission reduction targets set by the International Maritime Organization (IMO) and the European Union (EU), namely reaching climate neutrality by 2050. In the medium to long term, ammonia holds promise as a renewable and low-carbon fuel. However, during the ammonia combustion cycle, nitrogen oxide (NOx) emissions increase concurrently, which are strictly regulated by the MARPOL 73/78 Convention. Therefore, it is imperative to implement solutions that optimize the combustion cycle to reduce NOx emissions. This paper conducts a numerical study on the adjustment of diesel and ammonia injection timings for a marine medium-speed engine MAN L23/30H with intake-port premixed ammonia and in-cylinder direct-injected diesel pilot ignition under high ammonia substitution rates. In preliminary experiments, it was observed that at a 90% substitution rate, the combustion efficiency and thermal efficiency were only around 71% and 24% respectively under 100% load conditions, and approximately 35% and 13% respectively under 50% load conditions, indicating a state of near misfire. Consequently, this study focuses on adjusting combustion control parameters to analyze their influence on combustion characteristics under high substitution rates. In summary, both combustion efficiency and indicated thermal efficiency exhibited an initial increase followed by a decrease under both 100% and 50% load conditions. This suggests that appropriate heating of the intake air is beneficial for efficient combustion of ammonia/diesel dual fuel, but excessively high intake temperatures have a detrimental effect, particularly under heavy load conditions, where excessively high intake temperatures lead to a significant reduction in combustion efficiency and indicated thermal efficiency. The optimal initial temperatures for 100% and 50% load conditions were determined to be 375K and 425K, respectively. Furthermore, it was inferred that for high ammonia substitution rates, a more efficient fuel injection strategy involves controlling the pilot diesel injection timing within the range of - 10 to - 20°CA.

A review on bridging the energy-waste Academy of Scientific and Innovative Resenexus: The role of refuse-derived fuel in sustainable energy transitions in India.

Recycling end-of-life automotive traction batteries is paramount in reducing greenhouse gas emissions and mitigating supply chain dependencies associated with critical raw materials utilized in producing electric vehicle batteries. Deploying disassembly technologies represents a crucial step in the pretreatment process, enhancing the recycling process's sustainability and profitability. This study evaluates disassembly technologies based on a multi-stage expert-driven research approach. We present a systematic stakeholder identification and analysis for the disassembly process step, resulting in the 14 relevant stakeholders. 65 expert interviews were then conducted with the relevant stakeholders and yielded a corpus of 16 evaluation criteria. Each criterion underwent a delphi evaluation process with 13 experts to ascertain its relative importance. Ultimately, another delphi panel was utilized to evaluate each disassembly technology conjunction with all identified criteria. To address potential uncertainties, the fuzzy delphi method was employed, resulting in two rounds until a consensus was achieved. Laser cutting and shredding emerged as particularly promising technological approaches, recommended for consideration by industrial stakeholders in the expansion of their facilities and by policymakers in the formulation of their regulatory environment. The developed methodological approach aims to systematically evaluate early-stage emerging technologies and has been validated by the given use case.

There are environmental and financial benefits to reducing iodinated contrast media (ICM) waste. While Imaging Bulk Package (IBP) bottles have been demonstrated to reduce contrast waste in adult hospitals, lower computed tomography (CT) volumes and smaller contrast doses pose challenges for utilizing IBP in children's hospitals. Primary outcome: quantification of CT contrast waste during a 6-month period at a single children's hospital. quantification of single-use product waste and greenhouse gas emissions, identification of the 12-h periods of highest contrast use, and estimation of reductions in contrast waste, single-use product use, costs, and greenhouse gas emissions by using IBP ICM during peak hours. All contrast-enhanced CT performed from January through June 2025 were reviewed. Volume of contrast wasted was calculated. The 12-h time period with the highest contrast-enhanced CT volume was determined. Reductions in contrast waste, single-use products, cost, and greenhouse gas emissions by using IBP ICM during these peak hours were estimated. Approximately 291 contrast-enhanced CT exams were performed per month. Mean contrast waste was 37mL per study, totaling 66 L of wasted contrast over 6months. Peak hours were 9 AM to 9 PM on weekdays. The mean ICM waste per exam was 37mL using single-dose bottles versus 17mL using IBP bottles during peak hours (P<0.001). Using IBP ICM during peak hours and single-use ICM at other times could reduce contrast waste by 56%, glass bottle waste by 33%, and save $40,740 per year. Using IBP during peak hours with a syringeless contrast injector would decrease greenhouse gas emissions by 72% due to added benefits of decreased waste of single-use plastics. Implementing IBP ICM during peak hours would substantially reduce contrast waste, single-use product waste, and costs at our hospital. Other children's hospitals may evaluate their contrast utilization practices, including quantification of contrast waste and single-use products, to identify opportunities to reduce waste through use of IBP and syringeless contrast injectors.

Water-floating solar photovoltaics (FPV) add to renewable energy capacity building without additional land requirements. We quantify the environmental impacts of FPV on inland water bodies with a focus on greenhouse gas (GHG) emissions and water consumption. We harmonize and compare all existing peer-reviewed life cycle assessments on FPV and add two case studies. We consider the full life cycle of FPV, including future (prospective) material recycling options, as well as changes in water evaporation and aquatic GHG emissions at the FPV location. On average, we computed an overall GHG footprint of 36 gCO2 kWh-1, similar to ground-based PV. Biogenic aquatic GHG emissions at the FPV location are expected to contribute a relatively minor share (1%-8%) to the GHG footprint of the FPV systems. Water savings due to prevented evaporation are much higher than the FPV systems' water consumption. Collectively, our findings support the continued development and deployment of FPV technology to aid the transition toward renewable energy supply.

The carbon-nitrogen (C-N) cycle is a pivotal natural process for maintaining an ecological balance. However, excessive nitrogen pollution and greenhouse gas (GHGs) emissions have disrupted this equilibrium. The many complex reaction pathways of carbon and nitrogen, along with fragmented research into these, have hindered practical application. Electrocatalysis as a transformative approach is expected to restore this balance. This perspective proposes the innovative concept of "Modular Electrocatalysis" as a highly efficient system designed to integrate the numerous segmented electrocatalytic C-N reactions. Here the underpinning aim is to deconstruct the complex C-N conversion process into controllable, simplified reaction steps achieved through the customized module unit combination and adjustable modular routes, facilitating the transformation of carbon- and nitrogen-containing pollutants into high-value-added chemicals such as amines and amides. In this perspective, the related challenges and potential solutions for the design of feasible modular catalytic routes will be presented. The significance of catalyst tailoring and reactor customization will be explored with a goal to reduce the underlying difficulties of integration in a functional industrial implementation, providing systematic guidance for artificial C-N cycling processes.

This study analyzes how national incentive programs can play a transformative role in facilitating green hydrogen adoption across emission-intensive industrial sectors. Despite the recognized potential of green hydrogen for industry decarbonization, its widespread uptake remains constrained by elevated costs, limited supporting infrastructure, and technological limitations. By evaluating system optimization strategies, including PV-Wind, PEM electrolyser, energy storage and hydrogen tank sizing, this research demonstrates that targeted incentives applied to the redevelopment of legacy industrial zones can substantially reduce the Levelized Cost of Hydrogen (LCOH) from 7.8 USD/kg in baseline scenarios to 4.5 USD/kg with incentives considered, while simultaneously achieving notable reductions in greenhouse gas (GHG) emissions from approximately 3.2 kgCO₂eq/kgH₂ to near 1.4 kgCO₂eq/kgH₂. The novelty of this work is fourfold. It presents the first techno-economic optimization of Power-to-Hydrogen (PtH) systems that explicitly quantifies the interaction between national incentive schemes (0–70% CAPEX subsidies) and optimal sizing of PV, wind, electrolyzer, and hydrogen storage for heavy industrial applications. It demonstrates a linear relationship between total capital investment and LCOH (R² > 0.96), enabling rapid cost estimation without full simulations. It identifies a critical threshold for battery storage cost reduction (≥50%) before batteries become economically viable in PtH systems without incentives. It also provides a comparative analysis of incentive effects versus projected equipment cost reductions (2030–2050), showing that incentives alone can achieve 43–54% LCOH reductions. In addition, this formulated control strategy aims to accomplish three main objectives such as satisfying hourly hydrogen demand, maximizing renewable electricity utilization, and minimizing grid electricity withdrawal. The economic effect of these incentives closely rivals anticipated declines in equipment expenses projected for the coming decade. Furthermore, the observed linear relationship between capital investment and LCOH enables precise cost modelling and streamlines decision-making for site-specific implementations, minimizing the need for additional simulations.

Human activities amplify climate-induced greenhouse gas emissions from small water bodies (SWBs), creating critical but unquantified feedback in the global carbon cycle. Here, by training machine learning models on 470 field observations and upscaling to a global database of 3.28 million water bodies, we quantify this human amplification, which drives SWBs to emit 84.5 Tg CO2 y-1 and 11.0 Tg CH4 y-1, a disproportionate share of total inland water emissions (15% of CO2 and 28% of CH4) from only 6% of Earth's surface area. This amplification is primarily fueled by agricultural nutrient loading and land use intensity, which elevate CH4 fluxes in agricultural catchments five times higher than those in forested systems. Future projections show this synergy will increase emissions by up to 30% (CO2) and 14% (CH4) by 2100 under SSP5-8.5, whereas sustainable pathways (SSP1-2.6) could mitigate this emission acceleration through nutrient mitigation efforts, a largely neglected feedback process in current climate change assessments.

Climate neutrality and renewable energy expansion demand multifunctional materials capable of simultaneous carbon sequestration and electrochemical energy storage. Agricultural residue biochar offers dual-function potential, yet conventional pyrolysis does not systematically optimize competing objectives. This study presents a simulation-based computational framework integrating multi-output random forest surrogate modeling with differential evolution algorithms to identify Pareto-optimal process configurations balancing specific surface area, CO2 adsorption, electrochemical capacitance, and carbon stability. 800 parameter combinations were evaluated across pyrolysis temperature (400-900°C), residence time (0.5-3.0h), heating rate (5-50°C min- 1), activation chemistry (KOH, [Formula: see text], [Formula: see text], NaOH), and five feedstock classes using calibrated response surfaces. The surrogate model achieved test-set [Formula: see text] of 0.971 (RMSE = 48.06 m2 g- 1 for specific surface area and 0.942 (RMSE = 6.67F g- 1 for specific capacitance on 160 independent samples; CO2 adsorption yielded [Formula: see text] = 0.788, while carbon stability index showed moderate fidelity ([Formula: see text] = 0.497, RMSE = 0.069), consistent with challenges in modeling recalcitrance from compositional proxies. Multi-objective optimization identified configurations with specific surface area of 1094 m2 g- 1, [Formula: see text] adsorption of 5.01 mmol g- 1, and specific capacitance of 114F g-1. Pyrolysis temperature was the dominant predictor (48% feature importance); hydrogen-to-carbon ratios below 0.4 demarcate recalcitrant materials suitable for millennial-scale sequestration. Optimized processing achieved feedstock-independent carbon stability (median 0.44-0.46) across all biomass types. Spatially explicit assessment indicates that EU-scale deployment could sequester 53.9 Mt[Formula: see text]e year-1, equivalent to 1.2% of total EU greenhouse gas emissions. Experimental validation of selected configurations constitutes the primary direction for future work.

As one of the world's fastest-growing sectors in terms of CO2 emissions, the aviation industry has an urgent need to reduce carbon emissions. Sustainable aviation fuels (SAFs) can achieve reductions of 80-85% in CO2 emissions compared to conventional aviation fuels. These fuels are derived from a diverse array of feedstocks and process technologies. Currently, commercially promising routes include the hydrotreatment of esters and fatty acids (HEFA), Fischer-Tropsch synthesis (FT), alcohol-jet synthesis (AtJ), and power-to-liquid (PtL) processes. Among them, the PtL route stands out for its use of feedstocks derived from industrial or atmospheric CO2 and green hydrogen, which aligns with the sustainable development goal of reducing greenhouse gas emissions. This strategy is poised to make significantly contributions towards achieving carbon neutrality in the aviation industry. Compared with the development of HEFA, FT and AtJ technologies, PtL remains in the nascent phase of laboratory exploration and development, with a lack of systematic analyses and summaries of the reaction mechanism and key catalyst research. Therefore, in this paper, we summarize the progress in understanding of the reaction mechanism and catalyst research for PtL SAF technology. We further dissect the impact of catalyst design and modulation on catalytic performance, aiming to offer insights and inspiration for the future development of cutting-edge catalysts in this domain.

Surgical care significantly contributes to greenhouse gas emissions, with operating rooms consuming three to six times more energy than other departments relying heavily on single-use materials and anaesthetic gases. We conducted a systematic review of literature from 2023 to 2025 following PRISMA guidelines. The PubMed, Scopus and Healthcare LCA databases were searched, and eligibility criteria were applied. A total of 26 studies met inclusion criteria. Data were extracted on each study’s scope and system boundaries, reported emission values, identified carbon hotspots, and any mitigation strategies evaluated. A structured quality assessment was conducted to evaluate the reliability of the included studies and to identify potential sources of bias. The included studies demonstrated wide variability in reported carbon footprints of surgery, ranging from under 5 kgCO₂e for minor procedures to over over 400 kgCO₂e for complex single-stage operations and approximately 1,000 kgCO₂e for whole multistage patient pathways. This systematic review underscores that surgical operations could have a significant carbon footprint, with emissions hotspots concentrated in consumable materials and energy consumption. It also reveals substantial variability and methodological heterogeneity in how surgical carbon footprints are calculated, pointing to the urgent need for standardized life-cycle based frameworks in surgical settings. Establishing common standards will enable more reliable benchmarking of surgical emissions and better comparisons across studies.

Nitrate and trihalomethanes are widespread chemicals in drinking water associated with colorectal and bladder cancer, respectively. Drinking water choices determine different exposure levels and environmental impacts. We assessed and compared health impacts and carbon footprint of drinking water options in Barcelona, Spain. Drinking water habits, trihalomethane and nitrate concentrations, and estimated disability adjusted life years (DALYs) of bladder and colorectal cancer in Barcelona were obtained. We defined 5 scenarios: (S1) current drinking water habits; hypothetical situations where everyone drinks (S2) tap water, (S3) bottled water, (S4) reverse osmosis-RO filtered water, and (S5) active carbon filtered water. Bladder cancer population fraction attributable to trihalomethanes and colorectal cancer attributable to nitrate was estimated for the different scenarios using published exposure-response functions. The total set of greenhouse gas emissions (CO2-equivalent Kg) generated by materials flow, energy resources, transportation, and waste disposal were calculated. Bottled water was the most used choice (52%), and the "all bottled water" scenario led to the highest carbon footprint. The "all filtered-RO" scenario yielded the lowest DALYs and "all tap water" yielded the lowest carbon footprint. Domestic filters may offer a compromise between health and environmental awareness in drinking water behavior that warrants future research. This study highlights how a combined approach of Health Impact Assessment and Carbon Footprint can be used to evaluate risks of different chemicals found in drinking water (trihalomethanes and nitrates) through various water consumption scenarios (including current one, all tap, bottled, filtered with reverse osmosis and active carbon). By incorporating environmental and health data into an urban context (Barcelona), this methodology substantiates the need for decision-making based on robust findings on both public health impacts and sustainability trade-offs for future policies. These findings underscore the significance of the drinking water choices in the community heavily depending on bottled water.

Blue hydrogen production plays a vital role in the global energy transition by offering a low-carbon alternative to conventional fossil fuels, helping to mitigate climate change and reduce greenhouse gas emissions. This study explores an integrated approach to blue hydrogen production by combining sorption-enhanced steam methane reforming (SE-SMR) with chemical looping water splitting (CLWS). The process was analyzed using Aspen Plus (Version 12.1) to evaluate its performance and energy efficiency. Methane (CH4) is converted into high-purity hydrogen (H2) (99.8%) while maintaining thermal self-sufficiency through heat supplied by the CLWS air reactor operating at 950°C. For a feed rate of 1000 kmol/h of methane, the system requires 59MW of thermal energy and yields 2.63 moles of hydrogen per mole of methane. The integrated configuration achieves a net efficiency of 79.3%, surpassing the conventional CLC + SE-SMR method. These findings suggest that the proposed system offers a promising pathway for sustainable hydrogen production with reduced carbon emissions.

Operating rooms contribute disproportionately to healthcare-related greenhouse gas emissions and waste generation. Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA) are high-volume procedures with increasing global incidence, yet pooled data on their environmental impact are lacking. A systematic review and pooled analysis were conducted in accordance with PRISMA guidelines (PROSPERO: CRD420261297449). PubMed, Embase, and Scopus were searched through October 31, 2025, for studies reporting total waste, recyclable waste, and carbon dioxide equivalent (CO₂e) emissions associated with primary THA and TKA. Seventeen studies, including 394 procedures, were included. Data extraction covered waste quantity, recyclable proportion, and carbon footprint. Random-effects models with inverse variance weighting were used to calculate pooled mean estimates. Standard deviations were estimated from reported ranges when not provided. Heterogeneity was assessed using I2 statistics. Pooled mean total waste per arthroplasty was 12.27kg (95% CI, 10.88-13.66). Recyclable waste averaged 1.97kg per procedure (95% CI, 1.64-2.31), representing 14.5% of total waste (95% CI, 11.99-17.02), and indicating substantial unrealized recycling potential. Carbon footprint estimates varied substantially by accounting methodology. Studies measuring waste-disposal emissions alone reported a pooled mean of 13.7kg CO₂e per case (95% CI, 11.32-16.08), whereas comprehensive life-cycle assessment (LCA) studies reported a pooled mean of 135.37kg CO₂e per case (95% CI, 74.91-195.83). Considerable inter-study heterogeneity reflected differences in waste segregation, recycling infrastructure, and carbon accounting methodologies. Primary THA and TKA generate substantial waste and carbon emissions, with low recycling rates across institutions. These findings provide benchmark data to inform sustainability initiatives, optimize resource use, and guide standardized environmental assessment frameworks in arthroplasty.

The Virtual Fracture Care (VFC) method is designed to minimise follow-up visits for trauma patients seen in the emergency department (ED) with non-complex and stable injuries by adopting a risk-sharing model. Given the healthcare sector's significant carbon footprint, this study aims to assess the environmental impact of VFC-pathway direct discharge with the standard pathway with inpatient follow-up, focusing on the treatment and follow-up of torus/greenstick fractures. A comparative cradle-to-grave life-cycle assessment was conducted at a Dutch ED. Data for material use, waste, packaging, transport, energy consumption, and staff and patient travel are included. Carbon footprints were calculated using SimaPro software with the ReCiPe 2016 method. The study compared the carbon footprints of the VFC pathway and standard pathway, identified key contributors, and performed a sensitivity and uncertainty analysis. The VFC pathway resulted in a reduction of 2.8 (95% CI 2.1 to 3.9) kilograms of carbon dioxide equivalent greenhouse gas emissions (kg CO₂-eq) per treatment compared with the standard pathway, which equates to an annual decrease of 625 kg CO₂-equivalents in 230 patients seen in our hospital. Key contributors to the difference in annual emissions were travel movements (411.7 kg CO₂-eq), materials (126.5 kg CO₂-eq) and packaging (6.9 kg CO₂-eq). Sensitivity analysis revealed that eliminating follow-up visits could result in an annual reduction of 805 kg CO₂-eq, if all patients travelled by car. The VFC pathway reduces the CO₂ emission of treating torus/greenstick fractures, primarily by decreasing patient travel, while patient satisfaction and material use do not increase. Broader adoption of a risk-sharing model, that is digitally supported, may reduce environmental impact across healthcare domains.