Journal of Material Cycles and Waste Management最新文献

To enhance the sorting efficiency of electrostatic separation for various conductive particles, a numerical model for the trajectory of conductive particles under the combined electric and gravitational fields was established. Initially, the distribution of the spatial electric field was analyzed using COMSOL Multiphysics, followed by the development of a program in MATLAB to calculate particle trajectories. The effects of particle size, voltage, angular velocity of the grounding roller, and the distance from the collection trough to the center of the grounding roller on the sorting efficiency of conductive particles (with radii larger than 1 mm) under positive high-voltage conditions were examined. Then the single-factor changing method and the response surface methodology were used to optimize the above parameters. The results showed that there was an inflection point for the angular velocity of the grounding roller; below this point, the sorting efficiency increased with the angular velocity, but beyond it, the efficiency decreased as the angular velocity continued to increase. Additionally, after the response surface methodology was used to optimize the parameters, the sorting efficiency was increased by 9 times. This study provides a theoretical foundation for the design and parameter control of new electrostatic separators.

Fly ash (FA), a byproduct of municipal solid waste incineration (MSWI), poses significant hazards to urban development, necessitating its sustainable treatment. This study proposes a systematic decision support tool to identify the most sustainable MSWI FA treatment technology among various options, considering diverse criteria. The research introduces a hybrid Multi-Criteria Decision-Making (MCDM) framework integrating the Grey Relational Coefficient (GRC) into the Analytical Network Process (ANP) for objective criterion weighting. Additionally, a Projection-based Programming (PbP) approach enhances the reliability of ranking MSWI FA treatment alternatives by reconciling disparate sequences from different MCDM techniques. This work pioneers the early application of MCDM methods in prioritizing sustainable MSWI FA treatment, offering two crucial mathematical contributions. Firstly, the GRC-ANP method objectively assigns weights by capturing statistical relationships among criteria. Secondly, the PbP approach consolidates varied MCDM outcomes to provide a reliable ranking. Testing five technologies against eight sustainability criteria validates the robustness and effectiveness of the framework, affirming its potential in aiding decision-making for sustainable MSWI FA treatment solutions.

This work focuses on analyzing the physical composition of municipal solid waste (MSW) and the physicochemical characterization of the organic fraction of municipal solid waste (OFMSW) in a city in Northeast Mexico to propose an adequate treatment and valorization system. Diverse samples were analyzed over 5 months at the city of Saltillo landfill, where the daily discarded MSW was classified into household (HW), central market waste (CMW), and public areas and parks waste (PPW). For the HW and CMW, the fraction with the highest proportion was the organic residues from food products, with 22.15 and 25.78%, followed by other organic wastes (manure, yard waste, leaves, etc.) at 12.58 and 10.24%, respectively. Furthermore, the organic fraction was segregated from the rest of the MSW and classified into four subtypes, and their physical composition and physicochemical characteristics were determined. The results contribute to laying the foundations for the proper treatment of the OFMSW not just in the studied region but also in cities with similar conditions. Moreover, the OFMSW’s feasibility in treating via bioenergy technologies is revealed, and this research proposes a biorefinery treatment pathway through dark fermentation followed by high solids anaerobic digestion generating bioenergy and diverse bioproducts.

There is growing interest in metrics for developing circular and sustainable products. Life Cycle Assessment (LCA) and the Material Circularity Indicator (MCI) are prominent for analyzing environmental performance and product circularity, respectively. This study compares these methodologies applied to a case of plastic parts made from virgin Polycarbonate + 10% Fiber Glass for smart electricity meters. Sensitivity analyses were conducted on the recycled content used and the final treatment of parts. Both methodologies are sensitive to recycled content usage. The best scenario (SA1-10) features 100% recycled content and full recycling of parts, while the worst scenario (SA2-1) uses 100% virgin content with all parts disposed of in landfills. The results highlight similarities and differences between the methodologies. MCI focuses on material source, life extension, and end-of-life treatment to measure circularity. LCA covers a broader range of impact categories, including resource use, human health, and ecosystem impacts, making it more comprehensive for environmental analysis. Both emphasize the importance of recycled content and end-of-life treatment, underscoring the benefits of recycling in reducing environmental impacts and enhancing circularity.

Despite the variety of technologies available for the valorization of biowaste, this fraction of municipal solid waste is usually disposed of in landfills and dumpsites in undeveloped and developing countries. The selection of technological strategies compatible with the reality of each location represents an essential role in the success and continuity of the operation of the facilities. The best strategy will result from combining different environmental, economic, social, and technical dimensions, confronted with the interests of the stakeholders and the legal and policy contexts. Due to the complexity of different criteria, alternatives, and interests, a Multi-criteria Decision-making (MCDM) methodology is recommended to ensure the quality of the decision-making process. This study presents a systematic review of publications that have applied multi-criteria analysis as a decision support tool for the selection of biowaste management strategies. The different stages of management are discussed separately, highlighting the change in paradigms over time. It was found that less than a hundred studies have addressed it so far, with Asia contributing to most publications. However, the timeline shows that the number of publications is increasing, with multi-criteria models representing great potential to support decisions at any individual management stage, from preventing food waste to using by-products. Integrated multi-criteria approach that combines all stages of biowaste management, however, is still scarce in the literature.

Fly ash (FA) was used to modify sludge-based biochar (SBC) to improve its phosphorus (P) adsorption capacity, which was conducted by adding FA in the dried sewage sludge before 600 °C pyrolysis. FA modification increased the surface area of SBC, decreased its average pore diameter, increased its Al and Fe contents, improved its crystallinity, and enhanced its maximal P adsorption capacity from 12.37 mg adsorbed P/g SBC (mg/g) to 14.05 mg/g. The P adsorption process was well fitted by the pseudo-second-order kinetic and Langmuir isotherm models, indicating that P adsorption onto SBC was a single molecular layer adsorption dominated by chemical adsorption. The P adsorption onto SBCs was spontaneous and endothermic. FA modification improved the reusability of SBC by increasing the retention rate from 74.9 ± 5.8% to 80.8 ± 5.4% after four adsorption and desorption cycles. FA modification changed the P adsorption mechanism of SBC from ligand exchange, electrostatic attraction, and ion exchange to surface inner-sphere complex formation, electrostatic attraction, and ion exchange.

Emerging legal requirements will likely considerably heighten demand for high-quality recycled raw materials for e.g., packaging and automotive applications; key EU legislation mandates recycling as the future end-of-life option for municipal solid plastic waste. Yet recycled plastic use remains low due to safety concerns, undesirable aesthetic, olfactory, and mechanical properties, mainly attributable to contaminants present in recyclates. Advanced treatment options for recovered polypropylene (PP) packaging and the impact of such treatments on the polymer are currently poorly documented. We investigated the effectiveness of hot/cold washing and hot air devolatilization treatments in removing volatile substances from residential post-consumer PP plastic waste to improve its scope of application and value and to assess possible side effects on mechanical and processing parameters. Cold- and hot-washed recyclates exhibited similar contaminant levels and most substances were removed within 7 h. The recycling procedure had no adverse effects on mechanical or processing parameters although reprocessing caused polymer degradation, indicated by decreasing viscosity, elongation at break, and tensile strength. Washing and hot air devolatilization treatment of plastic wastes improve their scope of application and value by enhancing mechanical properties and considerably reducing the amounts of odorous substances, but is often not suited to high-quality applications, such as packaging. The dominance of packaging waste and strict legislation on food-grade recyclate applications will make widespread recyclate use challenging since it represents the primary use of plastic. Recyclate must consequently be extensively utilized in non-food contact applications until advances in waste sorting, washing, and devolatilization yield less contaminated recyclates with improved properties.

In the drive to reduce carbon emissions, the widespread adoption of electric vehicles (EVs) has surged, with Lithium-Ion Batteries (LIBs) emerging as the preferred power source due to their environmental benefits and technical advantages. LIBs contain a significant proportion (12%—20%) of graphite, crucial for their anode's electrode active material, sourced primarily through mining and synthesis. However, concerns arise as a few countries, notably China, Turkey, and Brazil, control over 78% of the world's natural graphite reserves, highlighting potential supply chain risks. In addition to that, synthesizing graphite is expensive, and with the ever-increasing demand for EVs, the prices are expected to increase even further. Recycling graphite from waste LIBs extracted from EVs and electronic devices could potentially be a secondary source of graphite. This recycled graphite source can mitigate supply chain risk, preserve natural resources, lower prices, and decrease environmental pollution. This comprehensive review examines various pretreatment techniques and methodologies for recycling graphite from waste LIBs. It also provides a comparative discussion on the purity and recovery of graphite, its challenges, and prospects in LIB recycling technologies. This review serves as a valuable guide for researchers seeking sustainable practices and recycling methodologies in the EV industry.

This work focuses on brewer’s spent grain (BSG) slow pyrolysis and examines the influence of the pyrolysis temperatures on the BSG biochar properties. The BSG biochar suitability as an energy vector, emphasizing its potential as a biofuel, was evaluated. Moreover, the biochar effects on lentil sprout germination were assessed, having practical implications for industries involved in seed production, nursery operations, and crop cultivation. Pyrolysis tests at 673, 773, and 873 K were carried out. Bioenergy indexes were calculated, and germination tests were carried out to obtain lentil sprouts. The BSG biochar obtained at 673 K presented the best performance for use as biofuel. Regarding the germination tests, the different biochar was applied at 4 doses, and the addition of biochar strongly influenced the evaluated parameters. The biochar obtained at 773 K and added at a dose of 5% doubled the values of mean germination time, seed vigor, and time for 50% of the seeds to emerge compared to the control, constituted only with distilled water. This evaluation adds a novel aspect providing valuable insights into the optimal pyrolysis conditions for producing BSG biochar, considering its use as an energy vector and substrate to obtain lentil sprouts.

Near-infrared (NIR) spectroscopy is an efficient and non-destructive method for the identification and classification of mixed plastics. In the identification process of NIR spectroscopy, the dataset proportion of each type of plastic obtained is imbalanced due to the difficulty of obtaining or special application environments. When the backpropagation neural network (BPNN) identification model identifies samples with imbalanced proportions, it may misidentify plastic categories with small proportions, or even fail to identify them. Considering this, this study proposes an improved BPNN identification method based on Bayesian regulation optimization. To illustrate the performance of the proposed model, NIR spectroscopy data from 200 samples of plastic-containing additives were analyzed for four plastics: acrylonitrile butadiene styrene, polyamide, polypropylene, and polycarbonate/acrylonitrile butadiene styrene blend. The spectral data was preprocessed by Savitzky-Golay smoothing and multivariate scatter correction. Competitive adaptive reweighted sampling method was used to extract information from the spectral data. The identification ability of the proposed model was evaluated using accuracy, recall and precision determined through macro and micro average The experimental results show that the overall accuracy of the proposed method to identify imbalanced small proportion plastics is improved by 7.7% on average compared with the method using the BPNN identification model.