Crude oil tank bottoms, a mix of oil, sediment, and water from crude oil collection tanks, are a significant waste stream associated with global oil production. In benchtop testing, as an intermediate evaluative step in progressive scaling toward industrial-scale treatment to recover oil from tank bottoms and to reduce waste, sonication was applied to samples from three California oilfields using only added water and mechanical mixing. The 2.2 kg sample size, over 40 times that used in most of the testing found in literature, utilized no chemicals during treatment. The tests employed a 1:4 ratio of sludge to added water in an acrylic tank with two 500-watt drop-in plate sonicators. Trial variables included sonication frequencies of 28 or 40 kilohertz, mixing speed, treatment duration, and oil collection methods. Oil recoveries up to 98.2% with mean recoveries of 27.4% were achieved using 0.2 kilowatt-hours per kilogram sample. This study indicated sonication treatment of crude oil tank bottoms with only added water and mixing was a potentially viable approach for waste oil recovery and waste minimization and warrants further investigation at even larger scale.

Processes for generating clean hydrogen from waste plastics through thermochemical methods such as pyrolysis and gasification are a promising solution for both waste management and clean energy initiatives. Then, this derived hydrogen powers the fuel cell, which produces electricity that can be directly fed to charge electric vehicles (EVs). Although this complex process has many challenges related to energy efficiency during the conversion processes—starting from the generation of hydrogen from thermochemical processes and hydrogen storage and followed by fueling the fuel cells and charging EV infrastructure—the simplistic conceptual modeling developed for this research demonstrates how an ecosystem of such processes can be made feasible commercially. Clean hydrogen generated using known techniques reported in the literature is promising for commercialization, but harnessing hydrogen from plastics offers additional benefits, such as reducing greenhouse gas (GHG) emissions. Overall, the feasibility of clean hydrogen using this methodology is not limited by potential cost inefficiencies, especially when savings from GHG emissions reduction are taken into account. EVs have become commercially viable thanks to high-energy-density Li-ion batteries. And therefore, research continues to optimize charging performance through the integration of renewable energy and battery storage systems. This study examines another potential of clean hydrogen: its use as a power source in grids, especially V-2-G (vehicle-to-grid) systems. Additionally, direct current (DC) power from a fuel cell powers an EV charger at DC input voltages for e-ambulances. In particular, this designed system operates on DC voltages throughout the power system, combining high-voltage direct current (HVDC) lines, renewable energy sources, DC-DC converters, DC EV chargers, and other supporting components. The literature review identified gaps in plastics production, waste management, and processes for converting them into useful energy. The presented model is a stepping stone towards a novel, innovative process for clean hydrogen production to power electric vehicle charging infrastructure for emergency response systems in healthcare, thereby improving public safety. The limitations of the study would be governed by the effective establishment of locations where waste management services are performed (for example, landfills) and adoption by local government authorities with deregulated power systems.

South Africa has a history of poor coordination in construction waste management, which has resulted in problems such as illegal dumping, a lack of legislation enforcement, and a lack of waste management practices. Problems linked with the management of construction waste have risen over the past decade because of increased waste production. This study explored the challenges to the enforcement of waste management practices by the Greater Tzaneen Local Municipality construction sector. A qualitative study was conducted in the construction sectors in Limpopo province. Purposive sampling technique was used to interview 24 participants. The interviews were recorded, transcribed verbatim, and analysed thematically. The findings highlight challenges such as employees’ behaviour and attitude, financial barriers, lack of knowledge and awareness, poor enforcement of the law, and inadequate resources that affects the construction waste management practices. This study draws attention to the challenges encountered when implementing effective waste management practices in the construction sector. The challenges are consistent with the broader challenges that the Sustainable Development Goals aim to solve. This study contributes to the endeavour to minimise environmental impact, promote sustainable practices, and preserve public health, while providing lessons that may inform similar contexts beyond the local municipality.

The growing global demand for clean and sustainable energy has reignited interest in nuclear power as a carbon-free alternative to fossil fuels, driving an increase in uranium mining. However, uranium extraction releases radioactive elements along with toxic and heavy metals, posing serious environmental risks. A combined narrative and systematic review was employed to evaluate remediation mechanisms, performance trends, sustainability, and emerging technological advancements. The results indicate that phytoremediation remains the most extensively studied and field-applicable technique, while phycoremediation offers rapid uptake in aqueous systems and mycoremediation demonstrates higher tolerance to extreme conditions. However, limitations such as slow remediation rates, site-specific performance, and scalability challenges restrict their widespread implementation. This study also highlights the emerging role of artificial intelligence and machine learning in optimizing remediation processes, although their application remains limited, particularly in fungal systems. Furthermore, the integration of nature-based solutions into nuclear waste management frameworks, aligned with international safety standards, presents a promising pathway for sustainable remediation. Future research should focus on developing hybrid remediation strategies, establishing performance thresholds under high contamination conditions, and advancing AI-driven, site-specific optimization models to enhance efficiency and scalability.

Despite the significant environmental impact of the healthcare sector, with Germany’s system accounting for a large proportion of national emissions, quantitative sustainability research on specific medical procedures, such as those in dentistry, is critically scarce. This study aimed to address this issue by conducting a Life Cycle Assessment to quantify and compare the Global Warming Potential of the conventional analog and the digital (intraoral scanner) impression techniques for the manufacturing of single-tooth crowns in a German dental practice. The methodology employed a cradle-to-grave approach, defining a positive dental model as the functional unit and focusing on material consumption, waste streams, and equipment usage while excluding patient travel and facility energy. The results revealed that the digital impression procedure offers significant environmental advantages, with its average carbon footprint (approx. 550 CO2-eq) being nearly threefold lower than the analog impression (approx. 1620 g CO2-eq). This difference is primarily driven by the analog impression technique’s intensive use of disposable materials and the generation of contaminated waste requiring incineration. In contrast, the digital impression’s burden shifts to the manufacturing of the intraoral scanner, highlighting the importance of high clinical utilization to achieve the ecological benefit. This work concludes that the adoption of digital impression taking is a critical step towards more sustainable dentistry by promoting material avoidance and waste reduction, provided that high equipment utilization rates can be ensured. It should be noted that these results are specific to the regional context, particularly the German energy mix and national waste management standards, and may vary in different geographical settings

This study investigates the use of the fine fraction of Brazilian residual kaolin, a material with no pozzolanic activity according to the modified Chapelle test, as a partial cement replacement in rendering mortars. The kaolin was classified into three granulometric fractions (coarse: 150–300 µm, intermediate: 75–150 µm, and fine: <75 µm) and incorporated at two filler contents (10% and 20% by weight). Mineralogical and chemical analyses revealed that the fine fractions contained higher proportions of kaolinite and accessory oxides, while medium and coarse fractions were dominated by quartz. Intensity ratios from XRD confirmed greater structural disorder in the fine fraction, which was associated with higher water demand but also improved particle packing and pore refinement. Fresh state tests showed that mortars with fine kaolin maintained higher density and exhibited moderate increases in air content, whereas medium and coarse fractions promoted greater entrainment. In the hardened state, fine kaolin reduced water absorption by immersion and capillary rise, while medium and coarse fractions led to higher porosity. Mechanical tests confirmed these trends: although compressive and flexural strengths decreased with increasing substitution, mortars containing the fine kaolin fraction consistently exhibited more moderate strength losses than those with medium or coarse fractions, reflecting their enhanced packing efficiency and pore refinement. Tensile bond strength results further highlighted the positive contribution of the kaolin additions, as the mixtures with 10% coarse kaolin and 20% fine kaolin achieved adhesion values only about 7% and 4% lower, respectively, than the control mortar after 28 days. All mixtures surpassed the performance requirements of NBR 13281, demonstrating that the incorporation of residual kaolin—even at higher substitution levels—does not compromise adhesion and remains compatible with favorable cohesive failure modes in the mortar layer. Despite the lack of pozzolanic activity, residual kaolin was used due to its filler effect and capacity to enhance particle packing and pore refinement in rendering mortars. A life cycle assessment indicated that the partial substitution of cement with residual kaolin effectively reduces the environmental impacts of mortar production, particularly the global warming potential, when the residue is modeled as a by-product with a negligible environmental burden. This highlights the critical role of methodological choices in assessing the sustainability of industrial waste utilization.

The rapid growth and seasonal availability of agricultural materials, such as straws, stalks, husks, shells, and processing wastes, present both a disposal challenge and an opportunity for renewable fuel production. Solar-assisted thermochemical conversion, such as solar-driven pyrolysis, gasification, and hydrothermal routes, provides a pathway to produce bio-oils, syngas, and upgraded chars with substantially reduced fossil energy inputs compared to conventional thermal systems. Recent experimental research and plant-level techno-economic studies suggest that integrating concentrated solar thermal (CSP) collectors, falling particle receivers, or solar microwave hybrid heating with thermochemical reactors can reduce fossil auxiliary energy demand and enhance life-cycle greenhouse gas (GHG) performance. The primary challenges are operational intermittency and the capital costs of solar collectors. Alongside, machine learning (ML) and AI tools (surrogate models, Bayesian optimization, physics-informed neural networks) are accelerating feedstock screening, process control, and multi-objective optimization, significantly reducing experimental burden and improving the predictability of yields and emissions. This review presents recent experimental, modeling, and techno-economic literature to propose a unified classification of feedstocks, solar-integration modes, and AI roles. It reveals urgent research needs for standardized AI-ready datasets, long-term field demonstrations with thermal storage (e.g., integrating PCM), hybrid physics-ML models for interpretability, and region-specific TEA/LCA frameworks, which are most strongly recommended. Data’s reporting metrics and a reproducible dataset template are provided to accelerate translation from laboratory research to farm-level deployment.

In recent years, China has made strong national commitments to waste reduction and circular economy, including the implementation of mandatory municipal solid waste separation policies and the rollout of zero-waste city initiatives. These efforts represent a strategic shift toward systemic environmental governance. However, the outbreak of the COVID-19 pandemic in early 2020—and the subsequent implementation of the country’s stringent zero-COVID policy—led to an abrupt disruption of these programs. Under this policy, strict lockdowns, quarantine of both confirmed and suspected cases, and city-wide containment became top priorities, sidelining environmental initiatives such as waste separation and sustainable waste infrastructure development. This study investigates how Chinese residents’ motivations for waste separation evolved across three key phases: pre-pandemic, during the zero-COVID enforcement period, and post-pandemic recovery. Grounded in the Theory of Planned Behavior and pro-environmental behavior theory, we developed an extended model incorporating pandemic-related social, psychological, and policy variables. Based on 526 valid questionnaire responses collected in late 2023 in Shanghai, we conducted structural equation modeling and repeated-measures analysis. Findings reveal a significant shift from externally driven compliance—reliant on governmental enforcement and service provision—to internally motivated behavior based on environmental values and personal efficacy. This transition was most evident after the pandemic, suggesting the potential for sustained pro-environmental habits despite weakened policy enforcement. Our findings underscore the importance of strengthening internal drivers in environmental governance, especially under conditions where policy continuity is vulnerable to systemic shocks such as public health emergencies.

Advanced phosphorus (P) recycling from wastewater is critical for improving nutrient circularity and reducing soil pollution associated with the direct application of sewage sludge in agriculture. However, few studies evaluate the long-term environmental and economic trade-offs between recycled P products and raw sewage sludge application. This study compares struvite, vivianite, and dicalcium phosphate (CaP) as P alternatives to sludge to mitigate heavy metal accumulation in Spanish agricultural soils. Using data from 27,835 plots, heavy metal accumulation was simulated over 50- and 100-year fertilisation scenarios. The results indicate that continuous sludge application leads to widespread exceedances of zinc, copper, and cadmium, especially in alkaline soils, whereas substitution with recycled products can substantially reduce these risks. Vivianite balances P recycling and costs, CaP offers the best environmental performance but with higher investment, and struvite suits smaller regions prioritising environmental safety. Economic analysis favours advanced recycling over sludge, especially considering externalities such as soil remediation costs. Despite limitations, our findings emphasise the importance of integrating environmental externalities into economic assessments and the value of advanced P recycling for sustainable soil management.

The utilization of Solid Waste Compost (SWC) as an organic fertilizer (OF) in agriculture has garnered significant attention in recent years due to growing concerns about worsening waste management issues. This empirical study investigates paddy farmers’ perceptions of SWC under Sri Lanka’s organic farming policy and uniquely addresses its underexploited potential as an organic fertilizer. Data were collected from 254 respondents in the Attanagalla Divisional Secretariat Division via a structured questionnaire. Nine key performance indicators were established to evaluate SWC against other organic fertilizers considered for the study. Findings revealed that meeting the ‘required quantity’ OF was the most challenging aspect (91%) for organic paddy cultivation, while only 14.2% of paddy farmers were able to utilize SWC for paddy fields due to limited availability. Farmers appreciated SWC as the most effective in balancing pest–predator interactions, even surpassing straw; however, its availability lagged compared to alternatives such as straw. Farmers expressed a higher likelihood of adopting SWC if it met government certification standards. The findings conclude that, while increasing production of SWC could enhance its role as an organic fertilizer in paddy farming, achieving its quality standards for paddy farming through government standard certification is crucial for successful implementation.