Journal of Material Cycles and Waste Management最新文献

This study reports a pyrometallurgical route for recycling lithium cobalt oxide (LCO) based cathode materials via direct smelting at 1450 °C using manganese-free flux systems. The results demonstrate that aluminum present in the cathode assembly effectively acts as an in-situ reducing agent, thereby eliminating the need for external reductants. Two flux compositions MnO₂-SiO₂-Al₂O₃ and SiO₂-Al₂O₃ were systematically evaluated. The SiO₂-Al₂O₃ flux system exhibited superior performance, yielding a cobalt-rich alloy containing 95.1 wt% Co and 3.2 wt% Ni, with only trace amounts of copper and iron. While MnO₂-SiO₂-Al₂O₃ flux system resulted in Mn incorporation into the recovered metal from the smelting process. Phase and compositional analyses using X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), and field-emission scanning electron microscopy (FESEM) confirmed the formation of Co-Ni alloy phases. Lithium and aluminum were preferentially partitioned into the slag phase, enabling clean metal-slag separation. The process achieved an overall metal recovery of approximately 100% and 99.65% for with and without MnO₂ containing flux, respectively. The Co recovery without pre-treatment steps such as roasting or decoking, offered a simplified and economically viable approach for LCO battery recycling. This work contributes to sustainable material cycle management by demonstrating an efficient pathway for the recovery of cobalt-rich alloys from spent lithium-ion batteries.

Composting is a waste management technique through the decomposition of organic matter into a useful product. This study evaluated the combined effects of pile composition and turning mechanism on composting dynamics using agricultural residues, livestock manure, phosphate‑solubilizing bacteria (PSB), and sugarcane mud cake. Three pile formulations (T1, T2, T3) were tested under manual and PTO‑driven mechanical turner at the Muhammad Nawaz Sharif University of Agriculture, Multan. Parameters, including temperature, C/N ratio, organic matter, pH, electrical conductivity, and nutrient concentrations (N, P, K), were monitored to evaluate the compost quality. Mechanical turning achieved thermophilic conditions (> 55 °C) more rapidly, shortened the composting period by half (7 vs. 14 weeks), and enhanced nutrient retention. Treatment T3 (straw + manure + PSB + mud cake) produced the most stable and nutrient‑rich compost (C/N < 20, OM reduction approx. 45%, N > 2200 mg kg⁻¹, P ~ 14 mg kg⁻¹, K ~ 700 mg kg⁻¹) in 7 weeks. These findings demonstrate that optimizing feedstock recipes and applying mechanized aeration can generate mature, enriched compost in reduced timeframes under local conditions The results support mechanized windrow composting as a practical strategy for sustainable agricultural waste management and nutrient recovery.

The geopolymer method, as an important treatment method for heavy metal pollution in lead-zinc smelting slag, has advantages such as being green and efficient. However, it still faces problems such as poor solidification and stabilization efficiency and insufficient long-term stability. Therefore, this thesis proposes to introduce biomass to prepare a smelting slag-biochar composite geopolymer (SBGP) to achieve the solidification and stabilization of heavy metals in lead-zinc smelting slag. Through factor optimization, it is determined that the optimal process conditions for the solidification and stabilization of SBGP are: 60% lead-zinc smelting slag (LZSS), 40% copper slag (CS), 1% biochar (BC), 5% alkali activator (NaOH), and a curing time of 28 days. The maximum compressive strength of the smelting slag-biochar composite geopolymer reaches 18.11 MPa, and the heavy metal stabilization rates of Pb²⁺ and Zn²⁺ after 28 days are 96.58% and 93.83% respectively. Mechanism analysis reveals that the geopolymer physically encapsulates heavy metal ions, and the functional groups provided by biochar complex with heavy metal ions. The purpose of solidifying and stabilizing heavy metal ions is achieved through the synergy of “physical encapsulation-chemical adsorption”.

Leachate from landfills is an important environmental reservoir of microplastics (MPs). This study integrated research results from both domestic and international sources to clarify the sources, occurrence characteristics, detection methods, and removal strategies of MPs in leachate, and discussed the complex pollutants on the surface of MPs. The research results show that 30% hydrogen peroxide has the best digestion effect in the pretreatment process of MPs. Fourier transform infrared spectroscopy is the preferred characterization method for MPs due to its cost-effectiveness and high efficiency; in addition, emerging technologies such as laser direct infrared spectroscopy can rapidly quantify MPs smaller than 20 micrometers. The removal of MPs is mainly achieved through physical separation processes, particularly membrane filtration. MPs have a large specific surface area, which can accumulate antibiotic-resistant bacteria and subsequently form biofilms. Aging further enhances surface roughness, increases the number of oxygen-containing functional groups, and enhances the carrier capacity of MPs for various environmental pollutants. Biofilms can promote the spread of pollutants through selective enrichment. Current research efforts face several limitations, including the lack of standardized detection methods, the scarcity of long-term monitoring studies, and the focus on single pollutants. It is necessary to establish standardized analytical methods, conduct in-depth research on the combined effects of multiple pollutants, and explore innovative strategies to utilize the unique properties of MPs to target the removal of environmental pollutants, such as through the engineering modification of biofilm microorganisms to turn waste into wealth in future.

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Biodegradable polymers often fail to fully degrade due to structural and environmental factors. With increasing global use of biodegradable packaging, developing sustainable recycling methods such as pyrolysis has become a key priority. In this study, analytical pyrolysis hyphenated with gas chromatograph/mass spectrometry (Py-GC/MS) is used to assess the resource recovery potential of two biodegradable plastics, polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT)-PLA blend. These packaging materials were characterized for their elemental composition, thermal stability and structure using different techniques. The efficacy of HZSM-5 in the selective recovery of specific chemicals from the plastics was studied at 400 °C, 500 °C and 600 °C. Acetaldehyde, 1,4-dioxane-2,5-dione, and 3,6-dimethyl- (D-, L-lactide-) were identified as major products from non-catalytic pyrolysis of PLA. At 500 °C acetaldehyde was enhanced compared to 400 °C and 600 °C, whereas ester compounds were the dominant products at 400 °C. The primary products from non-catalytic pyrolysis of PBAT-PLA blend included 1,3-butadiene, 3-butenyl adipate, bis-(butenyl) adipate esters and cyclopentanone. This showed that C – C bond fission and further free radical reactions play key roles in PBAT pyrolysis. In situ catalytic pyrolysis using HZSM-5 predominantly promoted the formation of monocyclic and bicyclic aromatic compounds across all investigated temperatures, while a more diverse product distribution was observed at 600 °C. Notably, catalytic pyrolysis of the PBAT/PLA blend produced mainly C₆–C₁₂ gasoline-range hydrocarbons, due to the shape selective activity of HZSM-5.

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Global plastic waste demands innovative solutions like recycled plastics in asphalt pavements. This state of the art review systematically assesses health and ecosystem risks from volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) emitted by plastic-modified asphalt (PMA). Employing a comprehensive literature search strategy spanning 1997–2024, we reveal a critical research disparity: while extensive studies document PMA’s mechanical benefits, dedicated investigation of its emission characteristics remains nascent and fragmented. We detail VOC sampling and analysis methodologies across wet, dry, and mixed plastic incorporation methods, critically evaluating their suitability for PMA’s complex emission profiles. Our synthesis identifies contradictory findings in the limited literature, with studies reporting emission reduction, increased toxicity or irritants, and negligible or compound-specific changes; inconsistencies largely attributable to methodological variabilities. Certain polymers (particularly polyolefins like PE and PP) are well-studied, while more hazardous but common waste plastics (PVC, ABS, PS) are conspicuously underrepresented. PMA construction may generate elevated hazardous fumes with potential novel toxicants from polymer decomposition, yet comprehensive occupational exposure data and field validation remain absent. Critical knowledge gaps include systematic emission inventories by plastic type and method, field monitoring studies, long-term emission behavior, and standardized testing protocols. Though landfill reduction and enhanced durability are acknowledged advantages, resolving these emission-related uncertainties is imperative. This review argues that balanced research parallelizing mechanical optimization with environmental validation is crucial for legitimizing PMA as a credible component of circular waste management strategies, enabling truly sustainable, low-emission road paving.

Open dumping remains the most prevalent practice in India, leads to generation of leachate containing highly toxic metals that can impact surface and groundwater sources and surrounding ecosystems. The current study aims to examine the physicochemical and heavy metal characteristics of leachate collected from the dumpyard of Anantapur, India, and evaluate its effects on adjacent soil and groundwater. Further, it employs the Leachate Pollution Index (LPI), Enrichment Factor (EF), and Contamination Factors (Cf) to assess the intensity of pollution and trace contamination origins. The analysis revealed significantly hazardous leachate characteristics, including a Chemical Oxygen Demand (COD) of 19,200 mg/L, Chlorides at 6455 mg/L, and Total Dissolved Solids (TDS) of 9700 mg/L, all exceeding the acceptable national standards. Elevated concentrations of Pb (1.1 mg/L) and Cr (1.39 mg/L) suggest the presence of hazardous waste materials. The soil sample collected near to dump site revealed moderate to severe contamination with Cf (2.11–11.2) and EF of 2.8, highlighting significant anthropogenic sources of pollution, especially for Pb and Cu. The overall degree of contamination of 33.68 classifies the site as very highly contaminated. Groundwater samples from nearby locations to the dumpsite also showed elevated EC and Mn levels, confirming possible leachate infiltration.

Climate change driven by increasing greenhouse gas emissions has intensified the demand for technologies that can reduce and utilize these gases. Biological methane reduction and utilization technologies are gaining attention due to their environmental sustainability. In this study, we describe the methane-based biosynthesis of D-pantothenic acid (vitamin B5) using a newly isolated Type II methanotroph, Methylosinus sporium UOS2. Genome analysis of the UOS2 strain, isolated from wastewater, revealed a complete D-pantothenic acid biosynthetic pathway. Cultivation with methane as the sole carbon source confirmed its ability to produce D-pantothenic acid. Optimization of culture conditions resulted in a 55.3% increase in biomass and a 37.8% increase in D-pantothenic acid production (0.37 mg/L) compared to cultivation in ammonium-based medium. Furthermore, overexpression of panE, encoding ketopantoate reductase, led to a 3.5-fold increase in D-pantothenic acid production (1.29 mg/L) within 96 h. These findings demonstrate the feasibility of direct methane-to-vitamin conversion using M. sporium UOS2 and highlight that medium optimization combined with targeted gene overexpression is effective strategies to enhance production, laying the groundwork for future methane-based biorefineries.

The growth of electric vehicles leads to an increase in end-of-life battery systems, requiring scalable and safe disassembly processes for sustainable recycling. While prior research has advanced perception, planning, and robotic execution, experimentally validated integrated systems capable of handling real-world uncertainty remain limited. This study applies Design Science to develop and evaluate an AI-assisted semi-automated disassembly system combining optical perception, adaptive robotics, and modular process knowledge. The proposed system integrates 2D segmentation and 3D point cloud analysis to identify components and estimate their 6D pose, achieving Dice scores of up to 95.5% and a mean average precision of 63.4% for rotation estimation. Experimental validation demonstrates successful robotic unscrewing rates of up to 98.8% and reliable execution of integrated disassembly sequences in most test cases. However, results also show that fully autonomous operation remains limited under real-world uncertainty, particularly due to perception variability and environmental influences. Findings indicate that robust disassembly requires hybrid human–AI system architectures, positioning human–robot interaction as a structural design principle rather than a fallback solution. This extends research by conceptualizing AI-assisted disassembly as a human–AI socio-technical system for managing uncertainty. It demonstrates potential for improved safety, increased flexibility, and scalable battery recycling operations in practice.

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The rapid growth of waste electrical and electronic equipment, particularly discarded mobile phones, has raised significant environmental and economic concerns. Printed circuit boards (PCBs), as one of the main components of mobile phones, are rich secondary sources of valuable metals, especially gold, with concentrations several times higher than primary ores. In this study, micellar-enhanced ultrafiltration (MEUF) was investigated as a novel, green, and selective method for gold recovery from waste mobile phone PCBs. Different cationic and non-ionic surfactants were tested, and the non-ionic surfactant TX-100 exhibited superior performance in minimizing gold leakage and maximizing recovery efficiency. Optimization of operational parameters, including surfactant concentration, membrane pressure, and pH, resulted in a gold recovery efficiency of up to 96%. Furthermore, MEUF demonstrated high selectivity toward gold over other metals in both synthetic and real leachate samples. The findings highlight MEUF as an environmentally friendly, cost-effective, and highly efficient approach for sustainable management of e-waste and reducing dependence on conventional mining.