Journal of Material Cycles and Waste Management最新文献

The vast generation of silica‑rich iron ore tailings (IOT) poses major environmental and economic challenges. This study presents a hydrometallurgical route for selective silica recovery using ammonium bifluoride (NH₄HF₂) to produce high‑grade nanoscale amorphous silica. Near‑complete extraction (~ 98%) is achieved within 3 h at 80 °C with 30 wt% NH₄HF₂, and kinetic analysis indicates a mixed‑control mechanism (E_a = 16–18 kJ/mol). To model the recovery as a function of time, reagent concentration, and temperature, three machine learning (ML) techniques were compared: fully connected artificial neural network (ANN), random forest (RF), and least squares regression (LS). The ANN outperformed the others (R² = 0.995, RMSE = 0.028), providing a robust predictive tool that also enables flexible selection of conditions for 98% recovery with reduced reagent use. With the potential to recycle up to 95% of NH₄HF₂, the ANN‑optimized process enhances the economic feasibility of the industrial‑scale IOT valorization. Selective silica removal enriches the residual valuable elements and simplifies their downstream separation by circumventing silicate interference. By combining systematic experiments with ML, this work offers a data‑driven, scalable approach to transforming mining waste into a valuable resource, thereby reducing environmental burdens.

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The reuse and recycling of construction products are crucial strategies within the transition to circular economy in the construction sector. The aim of this study is to identify and analyze the main barriers influencing construction product reuse and recycling in the Berlin region and understand the connections among these barriers as a system. The system is fed with data obtained through interviews with key stakeholders active in the construction sector in the study region, which allows us to identify twelve significant barriers. Among the most prominent barriers are the high effort needed to comply with certifications and legislation and the low-level demand and low acceptance of recycled and reused construction products. Three important causal loops revealing direct and indirect connections among barriers are identified. These findings result in policy recommendations targeting regional relevant leverage points in the system, such as the implementation of end-of-waste criteria, the requirement of considering recycled and reused construction products in tenders and process digitalization.

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This study determines unit area debris (UAD) and earthquake waste amounts following the February 6, 2023, Earthquakes in Turkey. A field study was conducted in Malatya, one of the eleven cities severely affected by the earthquakes. The research involved the selection of residential reinforced concrete (RC) buildings, demolition of buildings, debris removal, and weighing debris trucks to calculate UAD values for structures categorized into three construction periods: ≤ 1999, 2000–2010, and 2011–2018. The UAD values were estimated using two field-based approaches developed to correct for debris originating from basement filling: Approach 1 determined the basement filling contribution through direct field observations, while Approach 2 quantified it via structural calculations. Approach 1 yielded average values of 0.845, 0.952, and 1.009 tons/m², while Approach 2 resulted in 0.933, 0.979, and 1.107 tons/m² for the respective periods. Based on these findings, earthquake debris generation was estimated to range from 93.9 to 159.3 million tons across the affected region, with the highest amounts occurring in Hatay, Kahramanmaraş and Malatya. These results highlight UAD’s importance for estimating waste across varying seismic codes. Further research into material properties and construction techniques will provide valuable insights for minimizing future debris generation.

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Construction waste remains a critical challenge in high-rise residential projects, particularly in rapidly urbanising regions. Despite extensive research on waste causation, there is limited empirical evidence on the effectiveness of structured operational interventions in real construction conditions. This study evaluates phase-based waste minimisation strategies using a longitudinal quasi-experimental design across twenty high-rise residential projects in Bengaluru, India. Material wastage was monitored over eight construction phases, generating a balanced panel dataset of 160 site–phase observations. Projects were categorised into intervention and non-intervention groups, with structured measures introduced from Phase 3 onwards. A two-way fixed-effects panel model was applied to control for site-specific and temporal variations. The results reveal a clear divergence in waste performance. Intervention sites achieved a 24.91% reduction in waste-related cost, whereas non-intervention sites recorded a 17.50% increase. Econometric analysis indicates a reduction of − 8.57 kg/m² in material waste intensity (p < 0.01), along with cost reductions of −₹15.61/m² and −₹9.01/m² at phase and cumulative levels, respectively. The findings demonstrate that construction waste is a controllable, process-driven outcome shaped by site-level practices. Structured interventions offer a practical and scalable pathway to improving material efficiency and cost performance in high-rise construction.

Composting is an integrated treatment system that promotes the resource recovery and harmless treatment of organic solid waste by regulating physicochemical conditions to drive microbial metabolism. As its core, the process is driven by microbial communities that degrade and transform organic matter, whose dynamic succession in turn governs elemental (e.g., C, N, P) cycling, humus formation, and the quality and stability of the end product. This paper systematically reviews the fundamental principles, technical challenges, optimization strategies, and product applications of composting. However, in practice, the process faces multiple challenges, including odor emissions, fluctuations in key operational parameters (e.g., pH, moisture, C/N ratio), and feedstock complexity. This review addresses the microbial mechanisms behind odor generation alongside with control techniques, while also summarizing strategies to enhance composting efficiency through parameter optimization and feedstock pretreatment. Establishing a multi-dimensional evaluation system is critical for scientifically assessing compost maturity and stability to ensure product quality. Once mature, the compost serves as a premium soil amendment and organic fertilizer, boosting crop growth and curbing chemical fertilizer use through improved soil structure, elevated fertility, and modulated microbial activity, thereby advancing sustainable agriculture. This review serves as a technical and theoretical guide for composting practices.

Fly ash (FA) from municipal solid waste incinerators (MSWI) poses significant environmental risks due to heavy metals in mobile states. This study presents the first field evaluation in Vietnam of MSWI FA stabilization using sodium dimethyldithiocarbamate (SDDC) at two major waste-to-energy (WtE) facilities. Sixteen samples were characterized before and after stabilization using SEM–EDX, XRF, TXRF, and XRD, combined with distilled water leaching tests. SDDC treatment induced notable morphological transformation from spherical particles to plate-like and prismatic aggregates, indicating the precipitation of metal–chelate complexes on particle surfaces. XRD analysis revealed that both raw FA and stabilized FA (SFA) share dominant crystalline phases cristobalite, coesite (SiO₂ polymorphs) and Al₂O₃, confirming that the bulk mineral matrix remained structurally stable after stabilization. However, XRF data showed significant compositional redistribution between the solid and mobile phases. Leaching tests showed that crude fly ash exceeded the limits of QCVN 07:2025/BTNMT - Vietnam’s National Technical Standard on Hazardous Waste - for Ni, Pb, and Cd by approximately 1.25–1.5 times, 9.5–11 times, and 9 times, respectively. In contrast, SFA showed progressively declining metal leachability, with dissolved concentrations below 5% from the ninth day onward, achieving full regulatory compliance.

Effective solid waste management can be achieved through systematic waste sorting and recycling. This study investigates primary school students’ willingness toward waste classification by evaluating the impacts of regional differences, demographic factors, and educational interventions. Through comprehensive analysis of area, age, gender, awareness and attitude factors, the results indicated that professional presentations played an important role in forming the correct waste classification awareness of students, while urban areas showed greater effectiveness in educational propaganda. However, broader waste type identification remains challenging, as only draft papers (DP) and discarded stationery (DS) achieved relatively high recognition accuracy rates among typical campus waste types. Correlation and logistic regression analyses further revealed that awareness and attitude significantly influenced students’ willingness to participate in waste classification. These findings highlighted the importance of early-stage environmental education and parental involvement in cultivating sustainable waste management behaviors. This study provided targeted recommendations for optimizing waste classification education in primary schools and offered useful references for environmental education policy development.

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The fashion industry heavily impacts the environment, with vast amounts of textile waste landfilled or incinerated each year. Recycling textiles offers a key path toward more sustainable practices. This review study summarizes textile sorting, as well as mechanical and chemical recycling technologies for synthetic textile waste under the closed-loop recycling model. Although mechanical recycling is the most commonly used method today for most waste textiles, for synthetic fabrics, the process can damage the fabrics and degrade the quality of the recovered fibers. In order to obtain the best recycling efficiency, chemical recycling is the recommended course of action. Polyester is the most common synthetic fiber available on the market today, so most current recycling methods focus on PET recycling. Additionally, polyester and cotton blends are also considered in recycling processes. Moreover, recycling technologies for polyamide are also gradually developing. In the meantime, this study also discusses the performance difference between recycled fabrics and virgin fabrics. Current experimental verification indicates that although the performance of recycled fabrics is not as high as virgin fabrics, the difference can be negligible. As brands increasingly adopt recycled fabrics to cut energy use, developing eco-friendly and cost-effective recycling methods for synthetic textiles is essential.

This study demonstrates a sustainable approach to converting nitrile rubber (NBR) scrap from glove production into value-added elastomers via a devulcanization process. The devulcanizing temperature, time, and devulcanization aid concentration were optimized. The optimal devulcanization condition (1.0 phr DPDS, 170 °C, 6 min) yielded recycled NBR (rNBR) with 20% reduction in cross-link density and 12.6% to 18.5% increase in sol fraction, respectively. Further focus of this study was to develop conductive rubber composites based on NBR scrap. The reinforcement and electrical conductivity of NR/rNBR blends with various multiwalled carbon nanotubes (MWCNTs) contents (0–5 phr) were studied. NR-rich blends (NR/rNBR = 75/25) exhibited reversion curing behavior, whereas rNBR-rich blends showed plateau curing curves due to improved thermal stability. Adding MWCNT nanoparticles boosted tensile strength and modulus in rNBR-rich blends. However, elongation declined because chain mobility became more restricted. Notably, electrical conductivity increased substantially with higher MWCNTs content, and the percolation threshold was lower in rNBR-rich blends (p_c = 0.35 phr). This improvement is attributed to residual crosslinked networks in rNBR that promote the formation of MWCNT networks in NR/rNBR blends. These findings highlight the potential of NR/rNBR/MWCNT composites to deliver enhanced mechanical and electrical properties while valorizing glove waste, advancing sustainable material applications.

This study investigates the use of Linz-Donawitz (LD) slag as a partial cement replacement at 0%, 5%, 10%, 15%, 20%, 25%, and 30% by mass in normal concrete (NCC) and self-compacting concrete (SCC) mixes. Fresh concrete properties, including slump flow, L-Box, and V-funnel tests were evaluated to assess workability and self-compacting behavior. Hardened properties such as compressive strength, split tensile strength, and ultrasonic pulse velocity were examined to determine the structural performance of both concrete mixes. The results indicated that LD slag exhibits cementitious characteristics that enhance the mechanical properties of concrete, with optimal performance at a 10% replacement. Beyond this level, further replacement led to a gradual decline in strength due to changes in the interfacial transition zone (ITZ) and matrix heterogeneity. Microstructural analysis revealed that SCC mixes developed a denser ITZ and greater formation of calcium silicate hydrate gels compared to NCC, contributing to a more homogeneous microstructure and higher strength. One-way ANOVA results confirmed that LD slag replacement had a statistically significant influence on the mechanical and non-destructive properties of the concrete mixes. Additionally, partial cement replacement with LD slag effectively reduced the Cradle-to-Site embodied carbon of the concrete, highlighting its potential for sustainable construction.