Journal of Material Cycles and Waste Management最新文献

Municipal solid waste management has a potential to increase circularity by reduction of virgin material extraction and use of secondary materials. A scenario analysis tool was developed to assess whether circular economy goals are attainable with the existing infrastructure and technologies by calculating sorting and recycling rates using waste amount and composition estimations. Three scenarios, Current Road (business as usual), Circular Road (improved sorting) and Frugal Road (waste reduction), were developed and implemented. Sorting rates targets for food waste are achieved in all scenarios. For plastic, sorting rate targets are achieved only for Circular and Frugal, while European Union recycling targets are not reached in any, showing the important role of recycling efficiency. Policy makers can use the scenario development approach of this study to evaluate if circular economy goals are attainable with the current system and assess the impact of key factors such as waste generation and sorting behavior. The scenario analysis tool can be utilized to simulate the effects of different measures in the waste amounts and composition, which is crucial for the planning of the future management system. Further, sorting and recycling rates provide quantitative information about the circularity gap and qualitative information on bottlenecks and opportunities.

The recycling of concrete waste and its utilization in new concrete production can be a great contribution to a sustainable environment. In the present study, the impact of recycled mortar powder (RMP) was accessed on fly ash (FA) based geopolymer concrete (GC). The RMP was substituted with FA in the range of 0–50%. The durability properties such as capillary suction test (CST), initial surface absorption test (ISAT) and acid attack test were accessed and strength property was also evaluated in terms of compressive strength at ambient curing. Further, the ultrasonic pulse velocity (UPV) test and electrical resistivity test were also conducted for all GC mixes. The present study outcome shows that the overall properties of GC improved with the addition of RMP up to 30%. Moreover, the addition of RMP provides the early activation of GC due to calcium (Ca) compounds present in RMP. The microstructural characteristics of GC mixes were analyzed using field emission scanning electronic microscopy (FESEM) along with Fourier transform infrared (FTIR) spectroscopy and it revealed that the presence of Ca compound in RMP form additional nucleation sites i.e., calcium/sodium alumina-silicate hydrate gel with a polymeric chain which enhance the overall properties of the GC.

Carbonization is a promising method of carbon fixation, but there has been little research on municipal solid waste (MSW) carbonization as a carbon capture, use, and storage technology. We focused on biomass- and fossil-derived carbon in samples produced at the Saikai City Carbonization Center and evaluated carbon fixation through the MSW carbonization process. We found that the total C content of carbonized fuels is approximately 50%, with fossil C accounting for 9.1–14.4%. Fossil carbon in MSW was considered to be derived mainly from polyethylene and polyamide (nylon 6–6). In terms of the carbon mass balance, negative emissions of 71,300–108,000 kg-CO₂/month can be achieved from carbonized fuels that are not burned, such as soil amendments, compared to the case wherein all carbon in MSW is released into the atmosphere. The fossil C content of carbonized fuels is affected by the composition of the input MSW, while the influences of waste quality, desalination time, and pyrolysis temperature changes of several tens of degrees Celsius are small. Landfill disposal of carbonized fuels is limited by the capacity of the final disposal sites. The consumption of this capacity can be reduced through the use of carbonized fuels as a soil amendment.

This study investigates the geotechnical performance of municipal solid waste fines (MSWF) stabilized with xanthan gum and agar gum. As urbanization escalates, the challenge of managing MSW becomes more critical, especially in India, projected to produce up to 436 million tonnes annually by 2050. Landfill mining yields material with poor engineering properties, necessitating effective stabilization techniques. This research evaluates the efficacy of xanthan and agar gums in enhancing the geotechnical properties of MSW fines. Various tests, including compaction, triaxial, and unconfined compressive strength, were conducted on samples subjected to different curing periods. The results indicate a substantial improvement in the mechanical properties of MSW fines treated with agar gum, including a maximum increase of 58% in unconfined compressive strength (UCS). Microstructural examinations confirm enhanced interparticle bonding, while leachate analysis shows a notable reduction in heavy metal release. Statistical assessments underscore the significance of curing time in determining the final properties of the treated MSW fines. Overall, agar gum emerges as a more effective biopolymer for MSW fines stabilization, with curing duration playing a vital role in achieving optimal geotechnical characteristics. These findings offer valuable insights for selecting appropriate bio-treatment methods for heterogeneous materials like MSW fines.

This study aims to design the onboard waste-to-energy process to dispose waste plastic debris floating in the ocean. Collected marine debris undergoes pretreatment such as freezing and pulverization process. The pretreated plastic waste is transformed into hydrogen through plasma gasification, separation and purification which finally produces electricity by fuel-cell system. The hydrogen separation and purification process consist of water gas shift reaction and pressure swing adsorption process. Lab-scale experiments for the separation and purification process were carried out as a preliminary study prior to designing a practical scale integrated system. For low-temperature water gas shift, Cu–Zn–Al catalyst calcined under nitrogen atmosphere outperformed typical commercial catalysts. Process simulations indicate the need of additional apparatus such as heat exchanger, dehumidifier, and compressor for practical operation of the combined waste-to-energy process. Practical operation window based on the deviation between the ideal performance obtained from simulations and the measured performance from experiments was discussed.

This study presents a novel approach to oil–water separation by repurposing coconut fibers and expanded polystyrene (EPS) into a hydrophobic sponge. Spherical sponges were fabricated and coated with a polystyrene solution to enhance hydrophobicity. Quantitative analysis revealed a high oil absorption capacity of 7.6 g/g, with sustained efficiency over ten reuse cycles. A circular economy-aligned method for separating and recovering coconut fibers and EPS was validated. This research highlights the potential of waste valorization in sustainable technology development. The developed sponge offers a promising solution for oil spill cleanup and water treatment, with implications for environmental conservation and resource efficiency.

The contamination of F inhibits the recovery of pure Li from spent Li-ion batteries (LIBs). In this study, we extracted F from a cathode material of spent Li-ion batteries by dry and wet processes and investigated the effect on Li recovery. In the dry process, F was removed by calcination at a controlled temperature in the presence of an F-fixing agent. In the wet process, F⁻ ions were removed by adding Ca(OH)₂ as a F-fixing agent to F-containing aqueous Li solution. Through sequential calcination (500 °C) and water leaching cycles, we achieved high Li- and F-leaching efficiencies of 87 and 93%, respectively. When the second calcination temperature (500 °C) was higher than the first (350 °C), a high-purity Li solution was attained from water leaching after the second calcination, in which the F⁻ concentration was approximately 1/10th that of the Li⁺ concentration. Furthermore, the wet process successfully removed 98% of F from a F-containing aqueous Li solution by adding Ca(OH)₂. Thus, pure Li was successfully extracted from spent LIBs by a carbothermal process using calcium salt and water leaching treatment. The proposed acid-free process facilitates the recovery of Li from spent LIBs, which is promising for the closed-loop recycling of Li.

The environmental and construction legislations are not modernized to control the adverse impacts of construction activities in Bangladesh. A large volume of Construction and Demolition (C&D) waste and carbon are annually released from this sector. This research was undertaken to investigate the Green Supply Chain Management (GSCM) practices and its implications during the implementation in constructions. Three construction industries and three related material manufacturers were selected for case study, and thirty industries combing both categories were investigated through questionnaire survey to unravel current GSCM practices, and its challenges and effect on constructions. Results revealed that market (76.67%) and supplier (91.03%) pressures promoted GSCM practices in construction industries, additionally internal factors played significant role (74.44%), whereas 60% regulations as external pressure. As GSCM elements, green manufacturing (90.83%), green purchasing (85.83%), internal environmental management (82.5%), investment recovery (86.66), and eco-design (93.33%) respondents agreed to improve the construction industry to reduce C&D waste and carbon emission. About 89% and 79% respondents acknowledged the environmental and economic performances, respectively improved by GSCM practices. Furthermore, 70–90% respondents opined financial/technical/human application as key barriers in GSCM practices. Finally, the GSCM practices reduced C&D waste and carbon emissions; however, it was not maintained regularly and strictly.

The world is facing a significant challenge due to substantial production of construction and demolition waste (CDW), leading to accumulation of landfills. The escalation of construction activity in urban and rural regions, driven by rapid urbanization, intensifies the challenge of increased CDW. To overcome and address the concerns about environmental sustainability, the use of recycled materials in diverse engineering infrastructure applications needs to be recommended. Recycled sand (RS) is one of the major by-products of CDW that is capable of being used in various infrastructure applications. To ensure the use of recycled sand as an alternative material to substitute natural sand (NS). Extensive laboratory tests such as micro-, macro-, and large-scale testing were carried out using large-scale direct shear test, plate load test, and a lightweight deflectometer test, to evaluate the physical and mechanical characteristics of recycled sand. In addition, the results were compared with natural sand in terms of bearing pressure (q), deformation modulus (E_PLT and E_LWD) of unreinforced, mechanically reinforced RS and NS samples, and its corresponding modulus improvement factor (MIF). The results indicate that the behavior of recycled sand was observed as similar to unreinforced and reinforced natural sand fill, and conclude that the recycled sand is a feasible material in substituting the natural sand for geotechnical engineered applications such as embankment fills, sandy subgrades, filler layers, and mechanically stabilized earth walls.

Proper management of post-consumer textile waste (PCTW) is vital to the sustainable development of circular economy. This study systematically analyze PCTW studies from 1995 to 2021 focusing on demographics, motivations, and reasons of PCTW management. A PRISMA approach is adopted for the bibliometric analysis. It is found that very few PCTW studies focused on the behavioral, physiologic, and cultural aspects. Recently, there is an increasing trend in PCTW publications, with a 73% increase in research output over the 15 years. USA stands out as the most productive country. Demographics such as income, age, and gender appeared to be the most significant role in shaping consumer behaviors, contributing to around 50% of the studies. There is a lack of studies involving participants below the age of 18, omitting one of the key stakeholders of PCTW management. We found gender bias in research participants, and many published PCTW studies focused exclusively on female consumers. Convenience and the condition of clothing items are important factors influencing consumer-disposal decisions, while environmental concerns are pivotal motivations driving recycling behaviors. More studies on gender stereotyping and cultural appropriation are recommended to better understand PCTW generation, recycling, and disposal behaviors.