Landfill leachate is an important secondary source of plasticizers; however, field-based evidence on their occurrence and full-scale treatment performance remains limited, particularly across different regions and treatment systems. In this study, raw leachate, disc-tube reverse osmosis (DTRO) permeate, and resin-polished effluent were collected from 11 landfill sites in 11 Chinese cities to investigate 10 target plasticizers, including bisphenol A (BPA), alkylphenols (APs), and phthalate esters (PAEs). PAEs dominated the concentration burden in raw leachate, ranging from 1.37 to 714.55 μg/L, whereas BPA and APs occurred at lower but widely detectable levels (0.56-3.43 μg/L). Pronounced spatial heterogeneity was observed among cities, suggesting that plasticizer profiles may be influenced by differences in waste-stream characteristics and leachate matrices. Across most sites, DTRO served as the primary removal barrier, achieving > 95 % removal of phenolic compounds, whereas ester removal efficiencies varied considerably (21.97-99.90 %). Meanwhile, the downstream resin unit further reduced membrane-permeable residuals, resulting in lower low-concentration levels across compounds and a more uniform residual distribution in the final effluent. Screening-level ecological risk assessment showed that raw leachate generally exhibited low to high ecological risk, with several PAE species reaching high-risk levels, whereas post-DTRO risk levels declined markedly but residual ecological risks persisted for certain compounds, particularly diisononyl phthalate (DINP) at multiple sites. Overall, this study provides multi-city field evidence on the occurrence patterns, compositional heterogeneity, stage-specific removal behavior, and residual ecological risks of plasticizers in landfill leachate, and highlights the complementary roles of DTRO and resin in full-scale treatment systems.
Landfill tipping fees influence the affordability and sustainability of municipal solid waste (MSW) management across the U.S. Past studies have often focused on single years or specific regions, leaving a limited understanding of long-term spatial and temporal disparities. This study analyzed consumer price index-adjusted tipping fees (2024 USD) for all 50 states from 2016 to 2024. Using the Jenks natural breaks method, states were grouped into Low (<$51/ton), Medium ($51-$70/ton), and High (>$70/ton) categories. These groups showed clear geographic patterns, with High-fee states concentrated in the Northeast, Medium-fee states more dispersed, and Low-fee states largely in the South. Average fees were $45.2/ton (Low), $57.3/ton (Medium), and $93.1/ton (High). The Northeast recorded the highest nominal fee growth (38.6%), compared to 17.6% in the South. Temporal analysis also revealed widening disparities, with High-fee states displaying greater variability and negatively skewed distributions, indicating underlying structural pressures driving cost extremes. A global Moran's I statistic of 0.37 and p = 0.013 confirmed significant spatial clustering. Regression analysis showed a strong income-fee relationship in the Medium group (R2 = 0.733) but weak associations in the Low (R2 = 0.155) and High (R2 = 0.063) groups. These findings offer data-driven insights to support more equitable and sustainable landfill pricing policies.
Recovering precious metals from spent automotive catalysts and realizing their high-value reuse is critical to ease resource shortages and advance sustainable industrial development. Conventional pyrometallurgical recovery consumes massive energy and generates secondary pollution; most existing techniques only extract Pd without exploring its subsequent high-value application. In this study, we developed an effective and green vacuum vaporization-deposition approach for the in-situ recovery and high-value utilization of palladium (Pd) from spent automotive catalysts. Under 1573 K and < 0.01 Pa, Pd was successfully transferred from spent automotive catalysts onto activated carbon (AC), enabling the preparation of a high-value Pd supported on activated carbon (Pd/AC) catalysts with a Pd loading of 61.42 mg/kg. During the process, no hazardous sulfur oxides such as SO2 were detected, and sulfur was predominantly released in the form of low-toxicity organosulfur compounds, effectively avoiding secondary environmental pollution caused by toxic sulfur oxide emissions. Based on theoretical adsorption simulations, the loading mechanism of Pd on AC is verified: Pd vaporized under the experimental conditions, was readily adsorbed by the defect sites of AC, and ultimately deposited on the AC surface following a vacancy defect adsorption pathway. The prepared Pd/AC exhibited uniformly dispersed Pd particles and demonstrated significantly enhanced hydrogen desorption ability and reduction performance. This work provides a novel approach for in-situ metal recovery and high-value reutilization of solid waste containing precious metals.
Despite the recognized importance of aeration in composting, the systematic optimization of aeration intensity across different stages, as well as the underlying mechanisms governing humification pathways and nitrogen transformation, remain poorly understood. This study addressed this gap by systematically comparing stage-specific aeration intensification during either the thermophilic (TAI) versus cooling (CAI) stage within an intermittent aeration framework, using temperature as a simple and reliable indicator for stage identification. Compared with moderate aeration (MA), TAI significantly enhanced compost maturity, increasing the degree of polymerization (DP) by 24.44 % and total nitrogen (TN) retention by 17.01 %. In contrast, CAI was less effective than MA in promoting humification,resulting in a 14.44 %lower DP;nevertheless, it still outperformed low aeration (LA) and achieved satisfactory maturity, while also improving nitrogen retention by 11.15 % relative to MA. Mechanistic evidence suggests that TAI promoted lignin degradation, generating aromatic skeletons that may couple with bioavailable organic nitrogen (BON) potentially through lignin-related humification processes, thereby contributing to the transformation of BON into stable humus. Furthermore, TAI optimized the microbial community, enriching thermophilic genera (e.g.,Thermobacillus,Ureibacillus), enhanced the electron transfer capacity of dissolved organic matter, and reinforced nitrification and ammonia assimilation while suppressing denitrification. These synergistic effects under TAI produced a highly humified and nitrogen-rich compost. This work provides an efficient and easily implementable aeration strategy that simultaneously advances humification and nitrogen conservation, leveraging widely available temperature sensors already standard in composting facilities, with significant promises for improving the quality and agronomic value of kitchen waste compost.
The recovery of critical metals from spent Ni-Co-Mn (NCM) cathodes commonly requires concentrated acids, auxiliary reductants, or energy-intensive treatment. Here, pressurized CO2-ascorbic acid leaching was integrated with leachate-based NCM811 regeneration. Under the optimized condition, 0.30 mol/L ascorbic acid, 7 MPa CO2, a solid-to-liquid ratio of 20 g/L, and 25 °C, Li was completely extracted within 80 min, while the extraction efficiencies of Ni, Co, and Mn reached 98.3 %, 97.1 %, and 97.2 %, respectively, without a separately added reducing agent. Control experiments confirmed that the increase in metal extraction arose from the coupled action of pressurized CO2 and ascorbic acid rather than from physical pressurization or CO2 alone. Equilibrium analysis further indicated that ascorbic acid provided the principal acidity and reducing capacity, while the dissolved CO2/H2CO3/HCO3- equilibrium can maintain protons availability during lattice dissolution. Kinetic fitting showed that the leaching behavior was best described by the product-layer diffusion model. SEM-EDS, XRD, and XPS revealed particle fragmentation, progressive disruption of layered structural order, and changes in surface valence states. The Li/Ni/Co/Mn-rich leachate was further converted into regenerated NCM811, which delivered discharge capacity of 180 mAh/g initially, retained 150 mAh/g after 200 cycles, and maintained 55-60 mAh/g at 5C. This approach achieves high metal extraction at room temperature using a relatively low organic-acid concentration without separately added reducing agent, while returning the recovered metals to functional cathode production.
This study investigates the correlation between environmental effectiveness and cost-efficiency in municipal solid waste (MSW) management within the European Union policy framework. Data from 5,516 Italian municipalities is utilized. MSW service effectiveness is evaluated using a composite indicator that aligns with the waste hierarchy. Quantile regression is applied to examine how disaggregated cost components are associated with service effectiveness across its distribution. Results show that effectiveness and cost-efficiency are complementary rather than conflicting objectives. Higher effectiveness is systematically associated with lower total costs per capita, with total costs decreasing by approximately 34% between the lowest- and highest-performing municipalities. This pattern is driven by a structural shift in expenditure from residual waste management to separate collection systems, reflecting changes in waste flows rather than reductions in service provision. The analysis also reveals significant differences across municipalities. Cost factors play a more significant role in low-performing municipalities, where improvements are mainly linked to service restructuring and cost reallocation. In contrast, their impact decreases in municipalities with higher effectiveness levels, where organizational and governance factors become important. These findings highlight the importance of tailored policy approaches. Operational restructuring is crucial for low-performing municipalities, while high-performing municipalities benefit more from improvements in governance, coordination, and citizen engagement.
Targeted analytical methods are widely used to quantify per- and polyfluoroalkyl substances (PFAS) in combustion flue-gas. However, interpretation of PFAS emission data is challenged by high shares of non-detects (NDs), heterogeneous limits of quantification (LoQs), and extensive target analyte lists. This study evaluates the influence of ND-treatment, target-list composition and LoQ distributions on PFAS-derived fluorine metrics using two pilot-scale incineration datasets.Both datasets exhibit high ND-shares and analyte-specific LoQs spanning several orders of magnitude. Current analytical target lists appear highly sensitive to the ND-substitution approach. However, sensitivity analyses demonstrated that this apparent sensitivity was governed by a small number of analytes exhibiting elevated LoQs. Excluding these analytes reduced variability among ND-substitution approaches by approximately 95 % in one dataset and by more than 99.9 % in the other, largely independent of the selected descriptive statistical parameter.Target-list reduction also decreased variability but provided little additional improvement. Consequently, the apparent influence of target-list composition was found to be largely attributable to the inclusion of a small number of analytes with exceptionally high LoQs.The findings indicate that apparent sensitivities to ND-treatment are governed primarily by analyte-specific LoQ distributions, and, to a lesser extent, by target-list composition. Robust assessment of PFAS-derived metrics therefore primarily requires critical evaluation of analytes exhibiting elevated LoQs, transparent handling of NDs and the application of lower- and upper-bound estimates. Future method development should prioritize harmonized LoQs, refinement of target lists, and inclusion of volatile PFAS and non-target analysis to improve PFAS emission assessment.
Although composting is widely regarded as a more environmentally sustainable alternative to landfilling, it remains a source of greenhouse gas emissions. Methane (CH4) and nitrous oxide (N2O) emissions from a full-scale Danish central garden waste composting facility were quantified during four measurement campaigns using flux chambers and the tracer gas dispersion method (TDM). Surface fluxes, pore gas composition, and temperature were measured in all on-site material piles, including active composting windrows and storage piles of mature compost and biofuel (the coarse fraction of shredded garden waste destined for energy recovery through incineration). The highest CH4 surface fluxes (2.1 g CH4 h-1 m-2) and pore gas CH4 concentrations (18 % v/v) were observed in composting windrows containing shredded and sorted material. The highest N2O fluxes (0.045 g N2O h-1 m-2) were measured in windrows composed of shredded but unsorted material. Although emissions from storage piles of shredded garden waste, biofuel, and mature compost were lower, they were not negligible. Pore gas CH4 concentrations increased with windrow age as oxygen availability declined. However, CH4 surface fluxes remained relatively constant, suggesting enhanced CH4 oxidation in the windrow surface layer. Average facility-scale emissions measured by TDM were 8.3 kg CH4 h-1 (range: 4.6-13 kg h-1) and 0.037 kg N2O h-1 (range: 0.019-0.054 kg h-1). These results demonstrate that both composting windrows and storage piles contribute to overall facility emissions. Comprehensive, sub-facility-scale measurements are therefore needed to identify key emission sources, support mitigation efforts, and optimize composting operations.
Material Recovery Facilities (MRFs) are essential to municipal recycling infrastructure, but face difficulties in sorting due to the growing complexity of recyclable material streams and contamination in their inputs. The limitations of traditional sorting technologies and reliance on manual sorters at MRFs have driven interest in integrating robotic systems that combine artificial intelligence (AI) detection with robotic actuation. This paper presents a review of AI and robotic sorting at MRFs, based on insights from recent literature and expert consultations. The literature review uncovered advances in AI algorithms and datasets, application of new sensors and multi-modal sensing systems, and novel robotic gripping and grasping strategies. Expert consultations identified a shift toward deploying AI systems as standalone detection tools, particularly for quality control and facility monitoring, and a movement away from robotic integration due to limitations in speed, reliability, and gripper effectiveness. The analysis reveals three key challenge areas: (1) practical deployment and economic viability of robotic sorting systems, (2) limitations in AI performance and data availability, and (3) robot-specific challenges related to gripping and grasping. The paper outlines future research directions to address these challenges and advance the field.
Because of its high dependence on imported phosphorus, Japan is striving to increase the reuse of phosphorus-rich sewage sludge (via direct application or composting) in agriculture rather than using incineration. However, the occurrence and behavior of pollutants in sewage sludge may pose environmental risks and have received limited attention until now. In this study, sewage sludge collected across Japan during a single sampling campaign was analyzed for heavy metals, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), per- and polyfluoroalkyl substances (PFASs), extractable organic fluorine, brominated flame retardants (BFRs), pharmaceuticals and personal care products (PPCPs), and endocrine-disrupting compounds (EDCs). One sludge sample exceeded the Japanese Cd limit more than elevenfold, while five of twelve samples exceeded the German regulatory limit for the sum of PFOA and PFOS. However, regulatory limits in Japan are currently available only for selected heavy metals among the analyzed pollutants. Therefore, the use of sewage sludge and sludge compost without comprehensive knowledge of their composition and appropriate regulatory limits on heavy metals and various organic pollutants, including emerging contaminants, could result in the uncontrolled release of these pollutants into agricultural soils and broader ecosystems.
Per- and polyfluoroalkyl substances (PFAS) in agricultural soils can migrate into crops and may alter soil greenhouse gas emissions, yet remediation strategies rarely address these risks simultaneously. This study evaluated tea waste biochar (TWB) produced at 400, 500, and 600 °C and applied at 5-20 g per pot by whole-soil mixing or surface-layer placement in a simulated PFAS-contaminated soil-leachate-plant system. Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) distributions, nitrous oxide (N2O) and methane (CH4) fluxes, and microbial responses were examined. TWB produced at 500 °C showed the most favorable combination of pore accessibility, surface hydrophobicity, and interfacial charge, with material-associated PFOS and PFOA enrichments of 0.12 and 0.57 μg/g, respectively. Whole-soil mixing with TWB-500 lowered soil and leachate PFAS levels and reduced PFAS concentrations in plant shoots by approximately 36% relative to the contaminated control. TWB treatments also reduced cumulative N2O emissions and enhanced net CH4 uptake. Metagenomic analysis showed lower relative abundances of genes associated with nitrogen fixation, ammonia oxidation, and several N2O-producing pathways, whereas CH4-cycling genes responded differently to the two application methods. Organic fluorine transformation genes were not enriched, indicating that PFAS control mainly resulted from physicochemical retention rather than enhanced microbial defluorination. Overall, TWB-500 can integrate PFAS stabilization with greenhouse gas management, but the optimal placement depends on the remediation objective: whole-soil mixing favors PFAS immobilization, whereas surface-layer application provides greater greenhouse gas mitigation.
The aim of the study was to assess the effectiveness of using peat (P) and lime (L) to immobilise metals and reduce salinity in contaminated harbour sediments (BS), in order to aid remediation. The contaminated BS1 and the uncontaminated BS2 were mixed with P and L in the following proportions: 60% BS and 40% P; 60% BS, 20% P and 20% L; 60% BS and 40% L. Greater effectiveness was found for lime than for peat. In mixtures with lime, the proportion of metals in the residual fraction increased more frequently. Both additives were effective in reducing the mobile fraction (F1) of metals. Only the addition of peat increased the F1 Cd due to a significant decrease in pH in the peat-containing mixtures. Salinity decreased significantly (by 14-61%) when additives were applied. Adding lime and peat to the sediments altered the composition of the functional groups and structures, which could be potentially responsible for interactions with metals. In particular, the addition of peat increased the pool of o-carboxyl groups, whereas the incorporation of lime, peat, or their mixture elevated the population of moderately and weakly acidic functional groups, including simple carboxylic and phenolic moieties. In lime-derived treatments, an increase in carbonate content was also observed. Peat reduced the fractal dimension of the surface, indicating a simplification of the structure and a reduction in surface roughness. Lime increased the hydrophilicity of BS, potentially influencing interactions between dissolved metal species and internal sorption sites. The most sensitive organisms were the plants (BS1, BS2), and Alivibrio fischeri (except BS2 + P + L).
Frequent landslides in construction solid waste (CSW) landfills pose significant safety risks. To address this, an integrated and practical two-tier framework is proposed for landslide risk assessment of CSW landfills, consisting of qualitative and quantitative assessments. In Tier 1, a multi-scale hazard and vulnerability assessment index system incorporating mitigation measures is established. This enables the rapid screening of multiple landfills to identify sites requiring prioritized attention, while also allowing for a comparative evaluation of risk levels both before and after the implementation of such measures. In Tier 2, a refined quantitative risk assessment is performed for the higher risk landfills identified in Tier 1, focusing on the spatial variability of CSW strength parameters. The application of F-N curves to quantify risk acceptability provides a quantitative basis for proposing targeted risk mitigation measures. Guangxi, China, with significant CSW disposal pressure, was chosen as the case study. Empirical findings include: (1) Among 131 CSW landfills, 12 sites were identified at a higher risk level through the initial screening, primarily located in Lingshan County; (2) Quantitative risk assessment of the high-risk Landfill No. 34 revealed that its societal risk fell within the unacceptable region under saturated conditions; (3) To address the unacceptable risk, comprehensive risk mitigation measures were proposed, with their effectiveness validated through comparative analysis. Overall, this two-tier framework optimizes the balance between regional screening efficiency and site-specific assessment accuracy, providing a reference for landslide risk management in CSW landfills.
Forest residues generated by tropical timber industries represent an abundant yet underutilized biowaste resource whose uncontrolled disposal contributes to greenhouse gas emissions and environmental degradation. This research assesses the potential of four major Cameroonian timber residues, Iroko (Milicia excelsa), Sapelli (Entandrophragma cylindricum), Movingui (Distemonanthus benthamianus), and Bilinga (Nauclea diderrichii), for sustainable biomethane production through hydrothermal-alkaline pretreatment followed by thermophilic anaerobic digestion. The objective was to improve the biodegradability of highly recalcitrant lignocellulosic biomass while assessing its contribution to renewable energy generation and GHG mitigation. Comprehensive physicochemical and structural characterizations of raw and pretreated substrates were performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) to elucidate modifications in crystallinity, surface chemistry, and biomass morphology induced by pretreatment. Methane yields increased from 29.10 ± 2.11 to 230.34 ± 2.32 NmL gVS⁻1 for Iroko, from 96.93 ± 3.24 to 220.21 ± 3.64 NmL gVS⁻1 for Sapelli, from 17.11 ± 3.43 to 150.64 ± 3.24 NmL gVS⁻1 for Movingui, and from 10.53 ± 4.52 to 120.43 ± 4.43 NmL gVS⁻1 for Bilinga. Kinetic analysis confirmed enhanced methane production rates and improved substrate conversion under thermophilic conditions following pretreatment. Among the investigated species, Sapelli exhibited the highest valorization potential, with an estimated biomethane production capacity of 8.35 million m3, equivalent to 91,868 MWh yr-1. Overall, the combined residues from the four timber species could generate approximately 189,076 MWh yr-1, highlighting a substantial opportunity for decentralized renewable energy production in rural and forest-dependent regions of Cameroon. Based on the experimentally determined biomethane potential, the theoretical utilization of the recovered biomethane corresponds to a greenhouse gas emission equivalent of approximately 33.83 × 106 kg CO2-eq yr⁻1, providing a quantitative indicator for evaluating its potential contribution to renewable energy systems. This study supports the integration of forest-residue biomethanation into sustainable waste management practices and low-carbon energy transition strategies in tropical forest regions.
Microplastics (MPs) are pervasive in landfill leachate and tend to be retained in membrane bioreactors (MBRs). However, the long-term effects on treatment performance of MBRs remain insufficiently understood. Herein, this study presents a 210-day laboratory experiment comparing a control MBR with two MPs-added MBRs continuously dosed with polystyrene (PS) or phenolic formaldehyde (PF) particles (150-250 µm). Results showed that MPs tended to accumulate in the sludge and settle at the reactor bottom in MBRs, with a small portion incorporated into the membrane cake layer. The final concentrations of MPs in the sludge were 63.1 ± 3.2 mg/L, and 46.4 ± 3.6 mg/L in the PS MPs, and PF MPs groups, respectively. The presence of MPs reduced the removal efficiencies of chemical oxygen demand in the landfill leachate, and intensified membrane fouling. Continuous exposure to MPs stimulated oxidative stress in sludge microorganisms and likely promoted elevated production of extracellular polymeric substances (EPS), thereby forming denser, smoother biofilms with higher organic content on the ultrafiltration membrane surface. By the end of operation, the transmembrane pressure of PS MPs and PF MPs groups were 23.34 kPa, and 33.85 kPa, respectively, which were significantly higher than the Control group (13.17 kPa). Metabolomics analysis further revealed enhancement of pyruvate, citrate cycle metabolism and increased levels of metabolites such as palmitic acid, trehalose and proline. These findings demonstrate that MPs drive metabolic shifts in microbial communities and enhance EPS secretion, leading to persistent membrane fouling in MBRs for landfill leachate treatment.
In the context of climate change, identifying alternative material sources has become essential, notably through the revalorization of waste materials. The construction industry is among the largest waste-generating sectors worldwide. A significant portion of this waste consists of formwork wood, which can account for up to one-third of construction-site waste. Due to demanding on-site conditions, formwork wood has a limited service life and is typically reused only one to four times before surface degradation compromises concrete quality. While the wood surface may no longer meet formwork requirements, it still retains structural integrity and significant reuse potential. This research investigates the remaining mechanical and structural properties of waste formwork wood to evaluate its suitability for structural reuse. Timber elements were collected from several construction sites across Belgium and assessed through visual grading as well as non-destructive and destructive testing methods. The experiments include ultrasonic pulse velocity measurements, compression tests, and four-point bending tests. Reusing reclaimed timber poses specific challenges, as each element differs in dimensions, material properties, and degree of deterioration, requiring adapted design and assessment strategies. This study explores the feasibility of employing short-length waste formwork wood in new structural applications by correlating non-destructive evaluation techniques with destructive test results, thereby contributing to more sustainable and resource-efficient construction practices.
Municipal solid waste (MSW) generation in university campuses across sub-Saharan Africa presents a critical management challenge and an underutilised energy recovery opportunity, compounded by structural information gaps including population undercounting and inadequate compositional data. This study applies an integrated machine learning (ML) framework to predict daily MSW generation, net calorific value (NCV), and electrical energy potential from primary empirical data collected at the University of Jos hostel complex, Nigeria. Four supervised regression algorithms - linear regression, random forests, gradient boosting, and a multi-layer perceptron neural network were trained and cross-validated on a 200-sample dataset constructed from 12-day empirical characterisation data (July 2021). Physical characterisation of 99.73 kg of hostel MSW identified food residue (35.50%) and polythene (32.44%) as the dominant fractions. The actual hostel population was field-estimated at 8,090 students 72.7% above official records yielding a per capita generation rate of 0.275 kg/cap/day and a total daily waste generation of 2.23 tons/day. Bomb calorimetry yielded a composite NCV of 15.23 MJ/kg, substantially exceeding the 7-8 MJ/kg viability threshold for thermal energy recovery. Linear regression achieved the highest MSW generation prediction accuracy (R2 = 0.9361, RMSE = 52.95 kg/day, CV = 0.9224 ± 0.0083). A weighted ensemble model combining three algorithms achieved the best energy potential prediction (R2 = 0.8286, RMSE = 133.80 kWh/day). The estimated monthly electrical potential of 2,776 kWh is sufficient to supply 2-4 individual campus facilities. Student population and food fraction were identified as the primary predictive features. The framework supports scenario-based planning under variable occupancy and enrollment conditions, and is directly transferable to other resource-constrained campuses across sub-Saharan Africa.
Municipal solid waste incineration fly ash (MSWI FA) poses great resource utilization challenges due to contained high concentration of heavy metals (HMs) and chlorine (Cl). In this study, lightweight aggregates (LWAs) were produced using FA and waste cathode ray tubes (CRT). The influences of sintering temperature and phosphates addition on HMs and Cl volatilization, pore structure and mineral phase evolution were investigated. When the mass ratio of FA to CRT was 7:3 and sintering temperature ranged from 1150 to 1200 °C, the removal efficiencies of lead (Pb), zinc (Zn) and cadmium (Cd) all exceeded 90%, whereas that of copper (Cu) surpassed 65%. The secondary fly ash (SFA) is rich in Cl and HMs, endowing it with promising potential for resource recovery. Phosphates had a negligible effect on the volatilization of HMs at high temperatures; however, they suppressed chlorine release via the formation of chlorapatite. As Ca3(PO4)2 dosage increased from 0 to 10%, Cl removal rates decreased from 95.86% to 85.28%, but the water-soluble Cl content in sintered products remained lower than 2%. The incorporation of CRT facilitated sintering at reduced temperatures. With SiN employed as a foaming agent, the total porosity rose markedly as the sintering temperature elevated, reaching at the maximum value of 68.67% under the FA:CRT mass ratio of 7:3 at 1200 °C. Environmental risk assessment verified that the sintered LWAs present low ecological risk.
Landfills serve as the primary disposal method for solid waste. However, due to variations in landfill construction and management standards, localized stress concentrations adjacent to the liner may occur, compounded by the heterogeneity of the subsurface structure. This leads to a particularly prominent problem of uncontrolled leachate leakage, posing a severe threat to the surrounding environment and groundwater safety. Geophysical methods are effective for detecting leachate in landfills. However, most of these methods have significant limitations, including signal attenuation by the waste medium, practical challenges related to field operations, uncertainties in data interpretation, and even potential damage to the liner that further elevates leakage risk. To address these limitations, this study develops a novel low-cost direct current (DC) electrical detection method for accurate localization of liner leakage points. Benefiting from the intrinsic properties of DC electrical detection, this method delivers favorable anti-interference performance and is relatively less susceptible to the heterogeneity of landfill waste. We first conduct systematic numerical simulations using COMSOL Multiphysics to quantify how leakage points alter the surface electric field distribution. On this basis, we establish a detection framework that identifies leakage occurrence and locates the defect position by analyzing the spatial characteristics of the electric field. Field experimental results confirm that the proposed method can reliably reflect the spatial distribution of leakage points, and enables fast, minimally invasive, and precise localization of liner defects. This method provides an efficient, low-impact technical alternative for routine landfill liner monitoring and leakage risk management.
The spatiotemporal greenhouse gas emissions (GHGs) and pathways to carbon neutrality for China's municipal solid waste (MSW) management remain underexplored. This study finds that China's MSW sector generated 2.5 × 108 tonnes of MSW in 2021, with a 51.69 % increase than 2011. Meanwhile, GHGs increased by 55.11 from 2011 to 2021. This increase was primarily driven by changes in MSW composition and treatment technologies, which increased direct emissions despite the growing benefits from energy and resource recovery. In 2021, GHG intensity was lowest in the Central and highest in the Northeast, showing substantial room for inland regions to improve resource recovery techniques. Scenario analysis suggests that, under the assumptions adopted in this study, net-zero emissions from MSW may be achievable as early as 2035 through food-waste composting, organic fertilizer production, and resource recovery from MSW incineration. By fully recovering the resources in MSW, projections showed that China can avoid 93.37 Mt CO2-eq GHGs and earn 87.73 billion USD by 2050. These findings provide insights for low-carbon MSW management and sustainable urban development in China and other countries.
