Journal of Material Cycles and Waste Management最新文献

Municipal organic solid waste in Palestine is causing several environmental and social problems. This paper studied management of this waste stream in the concept of urban mining and circular economy through composting and reuse the produced compost for different purposes as an indicator for the circular economy through the period extended from 2021 up to 2035. Two compost reuse scenarios are studied: use for agricultural purposes, and use as landfill cover materials. For agricultural purposes, compost can be used as an alternative fertilizer where nutrients in compost can replace the existing chemical fertilizers available in Palestine such as humic acid as a source of carbon, Ammonium Sulphate as a source of nitrogen, Triple Super Phosphate as a source of Phosphorus, and Potassium Phosphate source of Potassium. The estimated revenue from compost use in agriculture is USD 194.8 million in 2021 and USD 369.8 million in 2035. The estimated saving from using compost as landfill cover is USD 0.876 million annually, and USD 13.14 million during the 15 years’ study period. Implementation of the circular economy principles in municipal solid waste management through composting can close the materials recycling loop, generating extra income, and adding net revenue to the national economy.

The development of new methodologies and sustainable processes is a priority in the field of chemical engineering and nanotechnology. In this study, via an easy route, the nanohydrometallurgy process was applied to recover La from a real spent catalyst. The synthesis of superparamagnetic iron nanoparticles (Si@FeNPs) with different precursors was evaluated. The average particle diameter value was smaller when using sulfate precursors. La acid leaching extracted 76% and required process adjustments. The nanohydrometallurgy process separated La from the Ni present in the leach solution with 6 cycles. Therefore, two processes were proposed. The first is obtaining a product with 97% of La and Al as a contaminant. The second with 99% La purity. Nanohydrometallurgy proved to be an innovative and sustainable process, with the recyclability of Si@FeNPs, obtaining La from a secondary source. In this way, this nanohydrometallurgy process meets the concepts of circular economy and encompasses sustainable development goals (SDGs) nine and twelve of the United Nations.

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This paper advances the state-of-the-art on the suitability of using red ceramic waste in structural concrete as a green technology through an integrated approach coupling mechanical, durability, and environmental performance. Environmental impacts and embodied energy were assessed through the life cycle assessment of structural concrete (C30–C40) produced with 5–40% red ceramic waste considering compatible prescriptive mechanical properties and durability requirements for equivalent service life in a low-risk urban environment. Results show that while mechanical properties are preserved with up to 10% cement replacement, environmental impact reductions require 20–40% cement replacement, where the higher the concrete compressive strength, the higher the relative environmental benefits. For concrete mixtures produced with 40% red ceramic waste, the environmental load of C45, C40, and C35 are compatible and lower than that of plain C30. Due to the increasing amount of superplasticizer required to guarantee concrete workability, the environmental benefits of using red ceramic waste are slightly less evident for human toxicity than for other impact categories. The broad applicability of the proposed approach supports design strategies to improve the environmental suitability of reinforced concrete structures and contribute to effectively implementing sustainable practices in the construction industry.

With the implementation of the “carbon neutrality” strategy, waste resource-utilization technologies have become the focus of future research. P recovery from excess sludge (ES) is of great significance. In this paper, P recovery in excess sludge ash (ESA) of different incineration temperatures was studied. The experiment results showed that the optimal incineration temperature of ESA was 750 °C, and its total phosphorus content was 90.7 mg/g, which were three times heavier than the original sludge. As the incineration temperature increased from 650 °C to 850 °C, the more crystals appeared to be agglomerated and there was melting phenomenon on the surface of ESA. Higher temperatures were conducive to the AIP formation. The new minerals such as Ca₄(Mg.Fe)₅(PO4)₆ and (Ca.Mg)₃(PO4)₂ were produced in ESA of 800 °C and 850 °C. Under the optimal acid-leaching conditions that were leaching time of 90 min, liquid–solid ratio of 50:1 (mL/g), and sulfuric acid (H₂SO₄) concentration of 1 M, P leaching efficiencies could reach 100% in ESA of 700 °C and 750 °C, where P leaching contents were the most abundant and more suitable for P recovery. The research results provided theoretical basis and operational conditions for P recovery of excess sludge.

The basic characteristics of tungsten slag produced in the production of ammonium para tungstate (APT) and its ground tungsten slag powder were investigated. The mechanical strength characteristics and development of cement-solidified tungsten slag cementation system with raw tungsten slag mixed artificial sand as fine aggregate were discussed by cement solidification/stabilization method. The harmful metal content and leaching concentration of tungsten slag and its cement-solidified cementation system were compared. The test results show that the particle-size distribution of ground tungsten slag presents a more uniform characteristic. When the content of the ground tungsten slag is more than 30% as admixture, the strength ratio does not meet the requirements of the specification. In addition, when the raw tungsten slag be used partly as fine aggregate, the mechanical strength of cement-solidified tungsten slag cementation system is fine. Moreover, the cement solidification/stabilization technology can effectively reduce the leaching concentration of arsenic in tungsten slag. The mechanism of solidification/stabilization of arsenic by Portland cement includes adsorption and precipitate to form calcified arsenic insoluble.

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Fly ash carbonation is an effective method to achieve carbon reduction and stabilize the heavy metals. Supercritical CO₂ can facilitate the carbonation process due to its strong diffusivity, but the effect of parameters on the stabilisation characteristics under supercritical conditions is unclear. In this paper, the heavy metal leaching characteristics of carbonized fly ash under supercritical CO₂ conditions were comprehensively investigated. The experimental results showed that, increasing the pressure, applying mechanical force, increasing the rotational speed, raising the temperature, increasing the liquid-to-solid ratio, and adding calcium oxide all reduced the heavy metals leaching concentration. Compared with the original ash, Pb decreased by 38.65%, Cd by 31.66%, Hg by 47.06%, and As by 4.91% under supercritical conditions. After the fly ash carbonation, the influence of environmental factors such as the acid–base value, temperature, moisture, reaction time, and additives on the release characteristics were investigated. It was found that carbonized fly ash had good stability. At 30 °C, that leaching rate of Ni, Cr, Cd, Pb, Hg, and As after carbonation were 28.80%, 8.62%, 26.60%, 22.19%, 100.00% and 17.47%, respectively, lower than those of the original sample. The leaching rate of heavy metals increased with increasing temperature, and moisture aggravated the precipitation of heavy metals, which also increased with the reaction time. The addition of gypsum decreased the heavy metals leaching. The extraction experiments showed that after carbonation the heavy metals changed from active forms to stable residue states, except for Hg and As. Supercritical CO₂ carbonation has a good effect on the stabilization of heavy metals.

Converting food waste, such as garlic straw, into bioethanol offers a promising solution for both food waste management and meeting the increasing energy demands of a growing population. As a low-cost and renewable agro-industrial substrate, garlic straw holds significant potential for bioethanol production. To optimize the enzymatic conversion, pretreatment was performed to facilitate the enzymatic saccharification process by alkaline peroxide and sodium chlorite, resulting in a substrate consisting of 83.07% cellulose, 6.13% hemicelluloses, and 2.09% lignin. The bleached garlic straw (BGS) was hydrolyzed using a cellulolytic complex produced by the hypercellulosic mutant Penicillium occitanis Pol6, aiming to convert cellulose into glucose. The BGS was treated with various enzyme loading (10–50 FPU/g), at different BGS concentration (20–80 g/L) and tween 80 concentration (0–8 g/L) and at different reaction time (24–72 h). The hydrolysis yield from enzymatic saccharification of BGS were evaluated using a Box–Behnken Design. The optimum conditions for the hydrolysis yield were obtained based on surface and contour plots. The maximum predicted hydrolysis yield of 54.08% was obtained as follows: enzyme loading 40 FPU/g, BGS concentration 22 g/L, Tween 80 concentration 6 g/L and hydrolysis time 72 h. Fermentation of hydrolysates of bleached garlic straw (HBGS) carried out using Saccharomyces cerevisiae for 24 h showed that the sugar content decreased over time, while ethanol production increased. Besides, the highest bioethanol production (11.9 g/L) was observed in the 4% HBGS sample after 6 h of alcoholic fermentation. These findings proved the economical production of ethanol using garlic straw as a cheap waste material and also using a low-cost enzymes derivated from filamentous fungi.

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Antibiotics are extensively employed in the treatment of human and animal ailments. However, their excessive use and poor biodegradability have led to a notable accumulation of antibiotics in the environment, presenting potential health hazards to humans. In this study, tetracycline (TC) was selected as a representative antibiotic, and a recyclable material, Mn-ZIF-67, was synthesized to degrade TC through adsorption and peroxidase-like activity. Mn-ZIF-67 significantly enhances the peroxidase-like activity of ZIF-67. The removal efficiency of TC was boosted by 300% compared to ZIF-67 within a 10-min timeframe. With its high catalytic activity and stability, Mn-ZIF-67 exhibits significant promise for the swift degradation and elimination of antibiotics from the environment.

The present study assessed a mechanical biological treatment (MBT) based solid waste treatment and disposal (SWTD) facility of an Indian Municipality. The non-biodegradable and the biodegradable fractions are separated from the mixed waste by trommel screens. The biodegradable fraction is used to make compost. The nonbiodegradable fraction is recovered as a segregated combustible fraction (SCF)/solid recovered fuel (SRF), whereas the inert fraction is disposed of at the dump site. The compost produced from the biodegradable fraction had a lower percentage of total potash and organic carbon than the prescribed standards. The SCF/SRF of the trommel screen of 80 mm and 32 mm openings were found to have 4672.94 and 2728.26 kcal/Kg energy content, 60.43 and 57.69% volatile content, 3.31 and 7.80% ash content, and 6.81 and 4.38% fixed carbon content. The recovered SCF/SRF meets the fuel specification prescribed by the Indian Solid Waste Management (SWM) Rules 2016. However, the facility needs to address the issues and challenges related to the implementation and operation. The outcomes and learnings of the study are guiding sources for the researchers, waste treatment and disposal plant operators, designers, and policymakers of developing countries.

Our study presents an innovative material for application in the construction of biocomposites produced from agro-industrial by-products, constituted by the matrix of 70% raw rice bran, reinforced with 15% of rice husk fibers of different particle sizes (> 1 mm, > 500 µm, > 250 µm and < 250 µm) and 15% glycerol as a plasticizer. The materials were manually mixed and then molded by thermal compression in a hydraulic press with heating using a tray format. The molded parts were submitted to tests of biodegradability, contact angle, water absorption and impact resistance. The obtained results showed the influence of the incorporation of the rice husk fibers in the improvement of the evaluated properties when compared to the biocomposite produced only with rice bran. The different particle sizes of the rice husk fibers used in this study presented minor influence on the evaluated properties. Nevertheless, it should be noted that biocomposites with grain sizes > 250 µm and < 500 µm showed significant improvements, such as greater impact performance, higher initial contact angle and minor mass losses in composting experiments.