Journal of Material Cycles and Waste Management最新文献

During coal mining operations, large quantities of coal gangue are generated as by-products. Improper disposal of these materials poses significant threats to ecological environments. With the evolution of China’s policy framework and research focus, the ecological management and utilization of coal gangue have garnered increasing attention. This study systematically analyzes the physicochemical properties of coal gangue samples from various regions across China, summarizing their primary chemical compositions and mineralogical types. Based on these findings, a regionally adaptive classification and utilization strategy is proposed. Results indicate that aluminous coal gangue, rich in high-aluminum minerals, is suitable for the production of aluminum-based products; sandstone coal gangue, predominantly composed of quartz, can be employed in construction materials and engineering applications; clayey coal gangue, abundant in clay minerals, is appropriate for brick manufacturing, cement production, and certain energy recovery processes; calcareous coal gangue, mainly containing dolomite, calcite, and magnesite, is suitable for power generation or fertilizer production. This research provides a scientific basis for precise classification and efficient resource utilization of coal gangue, contributing to the large-scale, green management of solid waste in mining areas under the “dual carbon” goals.

The goal of the research work is to manufacture a high performance geopolymer eco-binder, containing high amount of pure molecule (Si₂AlKO₆), from a very complex mixture of collected brick wastes using a strong KOH alkaline solution. The effect of the alkaline solution molarity and cure temperature on the geopolymerization process and the paste performance was studied. The study of the microstructure and texture of the geopolymer was carried out using many characterization techniques (FRX, XRD, FTIR, TG-DTA, SEM, EDX), highlighting the formation of the pure molecule mixed with amorphous and crystalline calcium aluminislicate phases. The correlation between them and the compressive strength was also studied. The results showed that the geopolymer formation depends on cure temperature and alkaline solution molarity, of which 60 °C and 8 M were the optimum parameters leading to obtain a high performance geopolymer rich in pure molecule. This was proved by the compressive strength, recording the high value (54 MPa) at 28 days of hardening. The synthesized geopolymer is a real alternative to ordinary Portland cement.

The prevention of environmental pollution, and waste generation in agricultural production has led to the re-evaluation, and reuse of harvest residues, and agricultural raw materials. Materials obtained by utilising these plant wastes have been shown to increase the organic matter content of the soil, and are used as growing media. This study investigates the effects of compost, cocopite (coconut fibre), and perlite on yield, and quality in pepper cultivation under soilless agriculture conditions. The study utilised 9 distinct growing media: (2:1) cocopite: perlite (Control) (C); (2:1) tomato compost: perlite (TP); (2:1) apple compost: perlite (AP); (2:1) grape compost: perlite (GP); (1:1:1) tomato compost: cocopite: perlite (TCP); (1:1:1) apple compost: cocopite: perlite (ACP); (1:1:1) grape compost: cocopite: perlite (GCP), and (1:1:1) apple: tomato: grape compost: cocopite: perlite (ATGCP); (1:1:1:1) apple: tomato: grape compost: perlite (ATGP). The highest marketable yield was recorded as 459.80 kg/da in the apple compost: cocopeat: perlite treatment. Utilisation of compost resulted in a 30.82% increase in marketable yield compared to the control. Among the other treatments, apple: perlite, and grape: cocopeat: perlite were found to be the most effective in terms of vitamin C content, and titratable acidity (TA), respectively. Conversely, pH, chlorophyll index, and water-soluble dry matter content remained unchanged. Consequently, it was determined that compost derived from tomato, and particularly apple pulp, can be effectively employed in the soilless cultivation of pepper, demonstrating enhanced efficacy compared to cocopeat, a commercial growing medium.

The increasing accumulation of electronic waste (e-waste) poses significant environmental and health hazards, necessitating innovative recycling strategies. In this study, waste cathode ray tube (CRT) panel glass powder is valorised as a sustainable filler in polymer composites, promoting a circular economy approach. The e-waste filler is prepared through ball milling of CRT panel glass and added with epoxy matrix through conventional casting method. The weight% of the CRT filler is varied as 0, 5, 10 and 15 in the epoxy matrix. The fabricated composites were subjected to accelerated weathering to assess their ability to withstand environmental conditions. The fabricated and accelerated weathered samples were systematically analysed for their mechanical and wear performance through tensile, flexural, impact, interlaminar shear strength (ILSS), Shore D hardness and two body wear tests. The tensile and flexural modulus values were found increasing with filler addition, resulting in increased stiffness and rigidity. Maximum tensile and flexural modulus of 1820.75 MPa (for 10% CRT) and 5281.27 MPa (for 15% CRT) are observed, which is 56.8% and 78.30% higher than neat epoxy. Shore D hardness and wear resistance also increased with CRT filler addition. However, incorporating CRT glass filler in epoxy shows reductions in elongation, tensile, flexural and interlaminar shear strength. Properties of weathered samples were lesser than the non-weathered one, particularly at the higher filler loadings. Despite reduced mechanical properties, the enhanced hardness and wear resistance make these composites suitable for electronic casings and wear-resistant applications while supporting sustainable material development and waste reduction.

This study explores the sustainable integration of ceramic waste into brick manufacturing, promoting efficient waste management while enhancing environmental sustainability. By diverting ceramic waste from landfills, the research demonstrates that bricks with ceramic waste exhibit superior mechanical properties. Specifically, bricks containing 40% ceramic waste powder (CWP) showed a 28% increase in compressive strength after 28 days, meeting Indian standards for porosity (10.33%) and water absorption. Beyond experimental validation, the study incorporates machine learning (ML) models—Support Vector Regression, Random Forest Regression, Gradient Boosting, XGBoost, and Multilayer Perceptron—to predict compressive strength. The Random Forest Regression model achieved the highest accuracy (R² = 0.96). A radar plot is used to compare model performance based on predictive accuracy, interpretability, and computational efficiency. This research combines experimental and computational approaches, paving the way for sustainable brick manufacturing by leveraging ceramic waste and advanced predictive modeling.

The poor stability of steel slag hinders steel slag’s large-scale utilization. Five different types of steel slag were chosen for tests, including rotary slag, thermally sprayed slag, and thermally processed slag. Citric acid was used to improve the stability of steel slag and prepare high abrasion-resistant hydraulic concrete. Stability of steel slag for use as aggregate decreased as rotary slag > hot-curing slag > hot-splash slag. Hot-spray slag exhibited non-uniform expansion due to surface-enriched free CaO (f-CaO) on large mineral particles. Immersing rotary slag in 0.034 M citric acid for 3 days transformed surface f-CaO and free magnesium oxide (f-MgO) into calcium citrate and magnesium hydroxide, reducing mortar autoclave expansion rate to 0.04%. Using this modified rotary slag as fine and coarse aggregate for hydraulic concrete significantly enhanced concrete strength under equivalent water-binder ratios by 1–2 grade. Compared to granite aggregate concrete, abrasion resistance strength of hydraulic concrete using modified rotary slag aggregate was increased by 49.2%. Citric acid treatment effectively transforms steel slag into a high-performance, eco-friendly construction material, offering a scalable solution to reduce industrial waste and replace natural aggregates in hydraulic engineering.

This study aimed to quantify food waste to facilitate reporting aligned with the Sustainable Development Goals for Thailand. The required data was gathered through interviews covering retail, out-home consumption and households. The data collection was based on statistical sampling at a 95% confidence level with a potential error of less than 10% and included direct measurements for at least 10% of the total number of samples. The results indicated that Thailand generated 12 million tons of food waste per year, which mainly came from households (77%). The food waste index of household, food services and retail were 97, 29 and 16 kg/capita/year, respectively. In addition, discarded food waste from households was mainly edible parts (46%) which were disposed through the municipality waste service (84%), followed by using as animal feed (13%), and composting (2%). The main barrier for households in food waste was unplanned cooking, discarded food items, and lacking knowledge on food waste impacts. Raising public awareness along with supporting laws and provided facilities for waste separation were the key issues for policy recommendations. This study represented the first attempt to develop the national food waste baseline that could be useful for performance tracking towards sustainable food waste management.

Solid waste materials of concrete artificial reefs include scallop shells, wheat straw and fly ash. In this study, the basic properties (compressive strength and slump) and ecological effects (leaching and carbon fixation) of these materials were investigated. The results indicate that the compressive strength could meet the construction demands when scallop shells replace 40% gravel or 80% sand, fly ash replaces 30% cement, and the addition rate of wheat straw is less than 6% of the cement mass. Leaching experiments reveal that solid waste materials promote leaching of alkaline substances and silicate from artificial reefs. To a certain extent, leaching of alkaline substances could improve the capacity of the AR ecosystem and cope with ocean acidification. Leaching of silicate could alleviate the environmental problem of silicon limitation and promote marine productivity. Preliminary statistics reveal that reusing solid waste as concrete articial reefs could extend the carbon fixation of reef itself. Therefore, the use of wheat straw, scallop shells and fly ash as AR materials has ecological and economic benefits in reducing carbon emissions and expanding waste resource reuse methods.

Swine farming produces a large amount of organic waste, which can be effectively treated using anaerobic digestion. However, swine mortality waste, particularly bones and teeth, poses additional challenges, potentially resulting in blockages, accumulation in the biodigesters, and reduced efficiency. This study investigated the degradation of these materials in covered lagoon biodigesters (CLB) in both laboratory and full-scale settings. Under laboratory conditions, bone mass decreased by approximately 35% over 180 days, while tooth mass decreased by 22%. The degradation rate decreased over time as the organic fraction was consumed. SEM revealed structural changes, such as crack formation and loss of integrity. At real-scale conditions, there was minimal mass loss, indicating particle accumulation in bone pores. The annual accumulation of fixed solids in a CLB was calculated to be 3.4% of the biodigester’s total volume. These findings emphasize the importance of effective carcass shredding and sludge management strategies for preventing sedimentation and preserving biodigesters performance.

Conventional leaching processes for recycling spent hydroprocessing catalysts (SPHCs) are highly toxic and cause serious environmental pollution. Herein, we propose the direct use of nature-derived organic acids in ‘Citrus limon’ (C. limon) as an environmentally friendly method to extract valuable nickel (Ni), molybdenum (Mo), and vanadium (V) from SPHCs. The analysis of C. limon juice using high-performance liquid chromatography (HPLC) confirmed that it contained citric acid (> 0.35 molar), and other minute organic acids (malic acid and tartaric acid). The C. limon juice reaction with decoked SPHCs (DSHPCs) led to highly efficient leaching of metals (Ni: 94.7%, Mo: 92.7%, and V: 84.6%) under optimum conditions (C. limon juice concentration: 40%, temperature: 60 °C, mixing speed: 150 rpm, and DSHPCs concentration: 25 g/L). The dissolution of the metals was explained through a mixed kinetic model (Avrami equation), which suggested that diffusion control is the dominant leaching mechanism. After leaching, the residue (LR) showed significantly lower toxicity and improved surface textural properties (specific surface area − 236.25 m²/g). The improved textural properties of LR allow its potential reuse for preparing fresh hydroprocessing catalysts. Compared to current hazardous processes, this leaching process demonstrates a green and sustainable recycling solution for SHPCs.