Search Results (1,339)

The environmental challenges posed by heavy metal contamination in sludge leachate are becoming increasingly severe, necessitating the development of highly efficient remediation technologies. Among various treatment approaches, magnetic adsorbents have garnered significant attention as a promising solution due to their outstanding adsorption performance, convenient magnetic separation characteristics, and potential for regeneration. This paper systematically reviews the latest research progress on magnetic adsorbents designed for the complex system of sludge leachate, covering synthesis methods, surface functionalization, adsorption mechanisms, and performance evaluation. Key synthesis strategies are analyzed, including magnetic core preparation, inorganic coating, carbon composites, organic polymer grafting, functional molecule impregnation, and metal–organic framework (MOF) composites. The mechanisms by which these strategies influence material adsorption capacity, selectivity, and stability are elucidated. Despite significant achievements in laboratory studies, practical applications still face challenges such as large-scale synthesis, regeneration efficiency, cyclic stability, and adaptability to complex water bodies. Future research should focus on green synthetic pathways to advance the industrial application of structurally functional magnetic composite materials, providing systematic solutions from material design to process optimization for the sustainable remediation of heavy metal contamination in sludge leachate. Full article

Per- and polyfluoroalkyl substances (PFASs) include thousands of fluorinated organic compounds of anthropogenic origin. Their extensive use, combined with their high stability, has led to the widespread contamination of water and soil resources. Here, single-step foam fractionation enhanced soil washing was carried out for the remediation of PFAS-contaminated soil. Concentrations of target Perfluoroalkyl Carboxylic Acids (PFCAs) and Perfluoroalkane Sulfonic Acids (PFSAs) were monitored in foam and leachate along the duration of the treatment. Among PFCAs, only long-chain compounds peaked in foam at the beginning of the treatment. This was consistent with the increase in the sorption affinity to the air–water interface with chain length. The same behavior was observed also in PFSAs by comparing PFHXs, PFHpS and PFOS. The fraction of PFCAs still in the leachate after 40 min of treatment was found to decrease with chain length, with PFSAs showing a similar trend. PFAS removal significantly increased with soil particle size, ranging from 48.2 ± 3.2% (fraction < 0.063 µm) to 64.1 ± 1.9% (fraction > 2 mm). Final mass balance analyses detail PFAS distribution among soil, leachate, and foam, providing valuable information for the additional treatment required to destroy the PFAS load extracted from the contaminated soil. Full article

Landfills are complex repositories where macroplastics degrade into MPs. This review examines mechanical, chemical, and biological pathways of plastic fragmentation, as well as the occurrence, characteristics, and removal efficiency of MPs in landfill leachate. We also explore the landfill plastisphere from the perspective of this complex matrix, considering how plastic surfaces and microbial life may potentially converge to form a key biogeochemical interface that could influence carbon and nitrogen transformations The plastisphere’s complex surface structure drives microbial differentiation. Given its established links to GHG production in soil and water, we propose it likely represents a key contributor to GHG emissions in the more complex landfill environment. To bridge this conceptual gap, we review a mathematical scaffolding encompassing biofilm growth, polymer degradation kinetics, and gas flux, which can as a theoretical baseline requiring future in situ parameterization to evaluate plastisphere-driven biogeochemical interactions. Building on recent advances in monitoring and remote sensing technologies, including IOT networks, UAV imagery, and AI analysis, we outline a low-carbon landfill framework designed to optimize operational controls. This framework is described to simultaneously mitigate MP release and reduce GHG emissions, lowering carbon footprints. Amid surging plastic pollutants, this review underscores the necessity of holistic, integrated mitigation strategies. Full article

The rising global demand for lithium has led to substantial accumulation of lithium slag, a by-product of lithium carbonate production and a potential environmental contaminant. Leachates from this material contain various metal elements and may pose risks to ecosystems and organismal health. However, research on its neurotoxicity and underlying mechanisms remains limited. In this study, zebrafish embryos at 6 h post-fertilisation were exposed to varying concentrations of lithium slag leachate for 7 days. The leachate contained multiple metal ions (Li, Fe, Mn, Ni, Zn, As, Cr, Cu, Hg, Cd, Pb, etc.). Following exposure, significant metal accumulation was observed in larvae, accompanied by developmental malformations (yolk sac oedema, cardiac haemorrhage, and uninflated swim bladders). Behavioural assessment revealed reduced swimming distance and velocity, along with disrupted circadian rhythms. Biochemical analyses showed elevated Reactive oxygen species (ROS), Superoxide dismutase (SOD), Catalase (CAT), and Malondialdehyde (MDA), alongside decreased Glutathione (GSH), indicating oxidative stress. Transcriptomic analysis confirmed downregulation of core circadian genes. Neurotransmitter assays revealed decreased acetylcholine (Ach), noradrenaline (NE), and dopamine (DA), with increased gamma-aminobutyric acid (GABA) and serotonin (5-HT). These findings demonstrate that lithium slag leachate induces oxidative stress, circadian disruption, and neurobehavioural toxicity in zebrafish, providing important evidence for environmental risk assessment. Full article

Food waste filtrate (FW) and landfill leachate (LL) are high-strength organic wastewaters with complex compositions that pose significant challenges for conventional biological treatment. Anaerobic co-digestion is considered an effective strategy to improve process stability and methane recovery through substrate complementarity. In this study, an internal circulation (IC) anaerobic reactor was used to evaluate the co-digestion performance of FW and LL at different volumetric mixing ratios (3:7, 5:5, and 7:3). Methane production, COD removal, pH, volatile fatty acids (VFA), alkalinity, extracellular polymeric substances (EPS), enzyme activities, sludge morphology, and sludge structural and spectroscopic characteristics were analyzed to evaluate process performance and explore stability-related responses under different mixing ratios. The results showed that the 5:5 mixing ratio achieved the best overall performance. Under this condition, methane content remained at 78.79–81.60%, the volumetric methane production rate reached 893.38–1080.43 L CH₄/(m³·d), and methane yield was 0.219–0.265 L CH₄/g COD. COD removal efficiency was maintained at 86.93–88.35%. Meanwhile, the reactor operated within a relatively stable window, with pH of 6.98–7.80, VFA of 485.6–521.6 mg/L, alkalinity of 2000–3100 mg CaCO₃/L, and a VFA/TA ratio of 0.167–0.261. Compared with the other ratios, the 5:5 condition was associated with higher EPS levels, more favorable enzyme activity patterns, and a more compact sludge structure. Overall, FW-LL co-digestion exhibited clear ratio dependence, and the 5:5 mixing ratio provided the best balance between methane production, organic matter removal, and process stability. These findings offer quantitative support for substrate-ratio optimization and stable operation of anaerobic treatment systems for high-strength organic wastewaters. Full article

Municipal solid waste disposed of in open dumpsites and unlined landfills contaminates groundwater, soils, and air across urban areas of low- and middle-income countries. Nevertheless, impacts across all three environmental media have not been systematically assessed together. We conducted a PRISMA 2020-compliant systematic review of 286 peer-reviewed studies from PubMed, Dimensions, and OpenAlex, applying structured eligibility screening and quality appraisal using an adapted JBI checklist. Heavy metals—lead, cadmium, chromium, and zinc—were the most frequently detected contaminants in leachate and groundwater, commonly exceeding WHO drinking water guidelines by one to three orders of magnitude. Soil contamination by potentially toxic elements was documented at virtually all open dumpsites studied, persisting for decades after site closure. Particulate matter at South Asian MSW sites reached up to 41 times the WHO 2021 annual guideline. Microplastics acting as heavy metal carriers and dumpsite leachate as a source of antimicrobial resistance genes were identified as emerging risks outside standard monitoring frameworks. Non-carcinogenic hazard indices exceeded acceptable thresholds in the majority of health risk studies reviewed. Engineered containment was the strongest predictor of contamination severity across all sites. Phytoremediation, constructed wetlands, and biofiltration showed promise as mitigation approaches. Critical evidence gaps remain for Central Asia, harmonized reporting standards, and longitudinal monitoring data. Full article

Landfill leachate membrane concentrate (LLMC) is a high-salinity and high-organic wastewater stream that poses significant treatment challenges to conventional evaporation technologies. This study investigated the treatment performance and operating costs of a low-temperature atmospheric evaporation (LTAE) system for LLMC treatment under mild operating conditions. The effects of key operational parameters—including evaporation temperature (60–95 °C), pH (5–11), air–liquid mass ratio (A/L = 0.5–10), and concentration factor (CF = 5–20)—were systematically evaluated based on condensate quality parameters (UV₂₅₄, COD_Cr, and NH₃–N). Results demonstrated that the LTAE system achieved a higher concentration ratio (CF = 20) compared to the on-site mechanical vapor compression (MVC) system (CF ≈ 10). The optimal operating conditions for meeting effluent discharge standards were determined to be 70 °C, pH: 5, A/L = 5 and CF = 20. Under these conditions, the condensate contained ~5.6 mg/L NH₃–N and ~91.6 mg/L COD_Cr, while the concentrate reached ~4200 mg/L NH₃–N and ~38,000 mg/L COD_Cr, indicating that some organic matter and ammonia nitrogen escaped from the system and a gas scrubbing unit is recommended to minimize secondary pollution. Within the experimental range, the system achieved the highest K_cA = 22,871.25 kW/(m³·°C) and the highest K_dA reached 6.52 kg/m³·s. Economic analysis revealed a specific energy consumption of 110.5 kWh/t of freshwater produced. Despite the relatively high energy consumption, the LTAE system demonstrates considerable potential for the advanced treatment of high-organic wastewater, offering enhanced freshwater recovery under mild thermal conditions. This study provides theoretical and data support for the application of LTAE technology in LLMC treatment and similar challenging organic wastewater. Full article

Soil and water contamination with high nutrient concentrations from swine farms poses a risk to human and animal health. This study investigated the effects of biochar derived from young aromatic coconut husk (CH), coconut shell (CS), and their mixture (CHCS) on nutrient retention in biochar-amended soil columns for variable synthetic swine wastewater (SW) loading based on water use for piglets and fattening stalls. A 0.9 L leaching test column contained 3 g of each biochar type mixed with 300 g of soil. It was loaded daily with synthetic SW for 42 days at loading rates of 30 mL/day (piglet SW) and 60 mL/day (fattening SW). CH-amended soil was then selected to investigate the effect of rainfall rates at 0 (R0), 25 (R25), 70 (R70) and 140 (R140) mL/4 days on soil nutrient retention. Leachate was collected every 7 days to analyze nitrogen and phosphorus concentrations. The results showed that CH-amended soil had the highest retention of total nitrogen (TN) and phosphate among all treatments. For piglet SW, TN retention in CH-amended soil was 1.4–1.6 times higher than with CS and CHCS treatments, probably due to enhanced ammonium retention on exchangeable sites associated with the high cation exchange capacity of CH. High phosphate retention in CH-amended soil was linked to Ca²⁺ release from CH, facilitating phosphate precipitation. Moreover, CH-amended soil at R25 showed the highest ammonium retention but inhibited seed germination. Overall, CH-amended soil effectively retained nutrients and was suitable as a seedling growth medium, except under the R25 rainfall condition. Full article

Latin America faces growing challenges in the management of municipal solid waste (MSW). This is particularly evident in medium-sized and metropolitan cities where rapid urbanization, limited infrastructure, and high proportions of organic waste (40–70%) converge. This review synthesizes the most recent advances in organic waste management, valorization strategies, environmental performance, and policy frameworks in Mexico and Latin America. To provide a comprehensive overview, evidence from studies on informal recycling systems, route optimization, sustainable landfill siting, food waste valorization, life cycle assessments (LCAs), and biogas production is integrated. Techno-economic analyses of energy recovery from organic fractions are specifically reviewed. This review highlights that valorization of organic waste through composting, anaerobic digestion, food supplementation, and bioproduct generation can reduce greenhouse gas emissions by 40–70% compared to landfilling, with AD–composting hybrids achieving the highest reductions of 60–70%. Community composting achieved moderate reductions, 30–50%, but at significantly lower cost and with greater social co-benefits. These alternatives for valorizing the organic fraction extend the lifespan of both confined and open landfills. It also contributes to mitigating the public health impacts related to open dumping, disease vectors, and contaminated leachate. In short, this review also highlights shortcomings in policy coherence, financial mechanisms, source separation, and technology adoption. A strategic framework is proposed that prioritizes decentralized treatment systems, the integration of informal recyclers, tax incentives, community-based waste separation, and planning based on Life Cycle Assessment (LCA). The findings point to a viable strategy for transitioning from landfill dependency to circular waste management systems that improve the quality of life for the population of Latin America and the Caribbean. Full article

The cultivation of asparagus (Asparagus officinalis L.) is plagued by two serious issues: “asparagus decline” and “asparagus replant problem”. The average lifespan of an asparagus plant is 15 to 20 years. However, its productivity decreases after a few years (asparagus decline). Even when these asparagus plants are replaced with new ones, the new plants remain unproductive (asparagus replant problem). The main causes of these problems are a Fusarium infection and asparagus autotoxicity. Several reviews have been conducted on Fusarium. Despite the accumulation of evidence on asparagus autotoxicity in the literature over the past four decades, no review has focused specifically on asparagus autotoxicity. It has been reported that asparagus growth is inhibited by asparagus root residues, leachates, root exudates, and rhizosphere soils. Several phenylpropanoids, including trans-cinnamic acid, p-coumaric acid, caffeic acid, and ferulic acid, have been identified as asparagus autotoxic substances in these root residues, root exudates, rhizosphere soils, growth media, and/or plant tissues. Tryptophan, 3,4-methylenedioxycinnamic acid, and iso-agatharesinol were also identified as asparagus autotoxic substances. These substances may cause autotoxicity by disrupting phytohormone levels, cellular metabolism, impairing membrane function, and by inducing oxidative stress. Although cinnamic, p-coumaric, caffeic, and ferulic acids have been reported to act as antibiotics, these compounds have also been shown to weaken the defense mechanisms of asparagus against pathogen infection, and enhance the Fusarium pathogenicity. The presence of these autotoxic substances, coupled with a Fusarium infection, may create a vicious cycle that worsens “asparagus decline” and “asparagus replant problem”. This is the first review to focus on the asparagus autotoxicity. Full article

In this work, iron–phosphorus-based composite biochar (FPBC) was prepared by modification with the leachate of spent LiFePO₄ batteries. The effects of solution pH, dosage, adsorption time, initial concentration, and temperature on the adsorption performance of FPBC were investigated by batch adsorption experiments with Pb(II) and Sb(III) as the target pollutants, and the adsorption mechanism was explored using SEM, BET, XPS, FTIR and XRD characterization. The results indicated that as the initial pH of the solution increased, the removal efficiency of FPBC for Pb(II) gradually increased, while the removal efficiency for Sb(III) remained largely unchanged. The removal of Pb(II) and Sb(III) by FPBC fitted the pseudo-second-order kinetic model and the three-step intraparticle diffusion model, indicating that their removal was primarily controlled by chemical adsorption. Isothermal adsorption studies revealed that FPBC adsorption of Pb(II) better fitted the Langmuir and D-R models, suggesting a monolayer-dominated adsorption process. In contrast, adsorption of Sb(III) fitted the Langmuir, Freundlich, and Temkin models, suggesting a combination of monolayer and multilayer adsorption characteristics. The maximum adsorption capacities of FPBC for Pb(II) and Sb(III) were 312.54 mg·g⁻¹ and 219.20 mg·g⁻¹ at 30 °C, which were approximately 12.85 and 3.37 times those of commercial corn stalk biochar (BC). Thermodynamic analysis confirmed that the removal of Pb(II) and Sb(III) by FPBC was a spontaneous and endothermic process. In addition, FPBC demonstrated strong selective adsorption of Pb(II) in the binary co-adsorption system of Pb(II) and Sb(III). Mechanism studies indicated that Pb(II) removal primarily occurred through co-precipitation, complexation, ion exchange, and electrostatic adsorption, while Sb(III) was mainly adsorbed by FPBC via redox reactions and complexation. Therefore, this work not only provides a low-cost, high-performance adsorbent for the remediation of water contaminated with Pb(II) and Sb(III), but also opens up new avenues for the resource recovery of the leachate of spent LiFePO₄ batteries. Full article

Using perfluorooctanoic acid (PFOA) as a representative highly mobile solute to isolate hydrological controls, we investigated how slope influences the partitioning of vertical and lateral transport pathways. While vertical percolation has been widely examined using conventional column leaching tests, lateral transport driven by topographic gradients remain insufficiently quantified under controlled conditions. Here, laboratory-scale inclined leaching experiments were conducted to resolve the distribution of solute transport among vertical leachate, lateral runoff, and solid-phase retention under systematically varied slope angles (0°, 4°, 9°, and 20°), flow regimes, and leaching volumes. Results show that solute migration shifted from vertical-dominated transport under flat conditions (91% at 0°) to lateral-dominated export at moderate slopes, with lateral pathways accounting for up to 75% of the recovered mass at 9°. This pathway shift was well described by an exponential partitioning model, f₁(α) = f_max (1 − e^−kα), where f_max = 0.80 and k = 0.34°⁻¹ (R² = 0.97), indicating a critical crossover threshold at approximately 4° slope. Flow regime interacted with slope angle to modulate lateral transport efficiency: slower flow enhanced lateral export at moderate slopes, whereas faster flow promoted peak lateral transport under steeper conditions. In contrast, solid-phase retention remained consistently low (5–9%) across all treatments, indicating that the observed redistribution patterns were primarily governed by hydrological pathway partitioning rather than sorption processes. These results demonstrate that even modest topographic gradients can fundamentally alter solute transport pathways in sloped soils. The slope-dependent pathway partitioning framework developed here provides a process-based basis for incorporating lateral transport into hillslope hydrological models and for improving assessments of contaminant redistribution in both managed and natural landscapes. Full article

The long-term accumulation of phosphogypsum (PG) stacks has caused combined pollution of total phosphorus (TP), fluoride (F⁻), metals and metalloids (MMs), posing a severe threat to regional ecological security. To clarify the migration characteristics of pollutants in PG stacks, water leaching experiments and environmental risk assessment were conducted in 21 typical PG stacks in Southwest China. The spatial differentiation and vertical migration characteristics of pollutants under various coverage measures (high-density polyethylene (HDPE) film covering, soil covering, a composite of film–soil covering, and open-air storage) at different pH conditions were systematically analyzed. Results indicated that under open-air stockpiling conditions, the surface accumulation of TP and F⁻ was the most significant among all covering measures, corresponding to the highest environmental risk. In contrast, the membrane–soil composite covering exhibited the optimal inhibitory effect on the surface diffusion of TP and F⁻, but was less effective for metal and metalloid enrichment. Under acidic conditions (pH < 6), the vertical migration capacity of TP, F⁻, and MMs (Cu, Cd, Cr, Pb, and Zn) increased, leading to enrichment in the deep layers of the stack. With the increase in pH, the calcium-mediated precipitation–adsorption effect created a “geochemical barrier”, facilitating the solid-phase fixation of pollutants. A significant positive correlation among pollutants indicates synergistic release and fixation behaviors. In addition, a pH-controlled P-F-MM source-to-sink conceptual model was established, outlining the dissolution, precipitation, adsorption, fixation and re-enrichment pathway from fresh stock to leachate. This work provides insights for optimizing cover designs and pollution control strategies. Full article

Nanoparticles have been extensively studied due to their rapid development and increasing application in agriculture; however, the potential of magnetic fields to mitigate the toxic effects of ZnO nanoparticles (ZnO-NPs) remains unexplored. Magneto-priming can enhance seed performance without chemical inputs, contributing to green engineering, resource efficiency, and environmental sustainability. This study assesses the effectiveness of magneto-priming in enhancing triticale tolerance to ZnO-NP stress under both direct seed exposure and soil leachate treatments. Germination performance, seedling growth, root system development, and seedling vigor were assessed to characterize both phytotoxic effects and the mitigating role of magneto-priming. Direct seed exposure to ZnO-NPs reduced germination and slightly promoted root elongation at low doses, reflecting localized phytotoxicity. Magneto-priming increased shoot length by 28%, root length by 13–15%, roots per seed by 13%, and the Seedling Vigor Index (SVI) by 29% under direct exposure, promoting more balanced early seedling development. However, in soil-leachate assays, where nanoparticle mobility and bioavailability were limited, magneto-priming reduced germination, SVI, and shoot length while enhancing root traits, indicating a system-dependent trade-off. Overall, these results highlight that the benefits of magneto-priming in mitigating ZnO-NP stress are context-specific, with clear positive effects under direct exposure but mixed responses under leachate conditions, emphasizing the importance of the exposure pathway in early seedling establishment strategies. Full article

Landfill leachate is considered one of the most recalcitrant wastewaters due to its high organic strength, elevated ammonia concentrations, and complex chemical composition. This study evaluates integrated technologies for treating highly loaded landfill leachate from the Wadi Al-Asla landfill, Jeddah Saudi Arabia, using GPS-X^TM modeling combined with regulatory compliance and techno-economic assessment (TEA). The characterized mature leachate exhibited extremely high average concentrations of COD (17,050 mg L⁻¹), BOD₅ (10,058 mg L⁻¹), ammonia-N (989 mg L⁻¹), and total nitrogen (1223 mg L⁻¹), indicating severe pollution levels requiring integrated treatment technologies. Five (5) different scenarios involving integrated biological, physicochemical, and membrane-based processes were modelled, simulated and evaluated against local discharge standards complaince. Conventional and municipality-proposed upgrade configurations achieved ~80–83% COD removal, producing effluent COD > 2900 mg L⁻¹ and 1790–1801 mg L⁻¹ BOD₅, indicating persistent non-compliance for organic pollutants. Nitrogen removal improved substantially (93.7–95.7% ammonia-N and 91–93% total nitrogen removal), yet residual ammonia-N (44–63 mg L⁻¹) and total nitrogen (92–108 mg L⁻¹) remained above regulatory limits. Advanced hybrid systems achieved complete TSS removal and strong phosphorus control (TP ≤ 0.42 mg L⁻¹), while three(3) compartmental aerobic–anoxic membrane bioreactor coupled with reverse osmosis (MBR + RO) achieved near-complete nitrogen removal and reduced 90% COD removal. The lifecyle economic assessment indicated OPEX ranging from USD 1.1 to 5.6 m⁻³ of treated leachate with the aerobic–anoxic MBR + RO configuration yieding footprint advantage, lower CAPEX and moderate OPEX By combining process modeling, regulatory compliance evaluation, and economic assessment, this study provides a practical screening framework for selecting sustainable treatment strategies for high-strength landfill leachate and wastewater matices. Full article