Characteristics and pollution potential of leachate from municipal solid waste landfills: Practical examples from Poland and the Czech Republic and a comprehensive evaluation in a global context

Assessing the impacts and contamination potentials of landfill leachate on adjacent groundwater systems

Landfilling is a globally prevalent method for managing municipal solid waste disposal. Nonetheless, the potential for serious contamination and the significant regional disparities in the leachate produced pose varying degrees of risks to groundwater quality. Previous studies have focused on a single landfill or the same geo-climatic conditions, with a limited number of samples having resulted in a narrow distribution of landfill age and scale, which prevents the description of the pattern of change in landfill age and scale. As well as the effect of this change on the contaminants in the landfill leachate and surrounding groundwater is still unclear. Therefore, we sampled and analyzed leachate and surrounding groundwater from 62 landfills with different landfill ages, scales, and operating conditions in a region with dense and varied topography and climate. Aim to explore the effects of different landfill ages, scales, and operating conditions on contaminants in leachate and surrounding groundwater. Findings indicate that pollutant profiles in different media are influenced by the age, scale, and operational status of the landfill, and the impact of leachate on pollutant types and concentrations in groundwater is limited. A significant correlation exists between the concentration of contaminants in the groundwater affected by leaching from the impermeable layer and the age and scale of the landfill when compared to the leachate. The contamination potentials posed by different pollutants vary across environmental media. Total dissolved solids and NH4+-N in leachate presented high contamination potentials, whereas elemental metalloids (Mn, Al, Ba, and Fe) in the surrounding groundwater posed high environmental concerns. These insights furnish new avenues for monitoring, identification, and safeguarding against pollutants in landfills and proximate groundwater, which is imperative for the sustainable management of municipal waste.

Landfill leachate a potential challenge towards sustainable environmental management

The increasing amount of waste globally has led to a rise in the use of landfills, causing more pollutants to be released through landfill leachate. This leachate is a harmful mix formed from various types of waste at a specific site, and careful disposal is crucial to prevent harm to the environment. Understanding the physical and chemical properties, age differences, and types of landfills is essential to grasp how landfill leachate behaves in the environment. The use of Sustainable Development Goals (SDGs) in managing leachate is noticeable, as applying these goals directly is crucial in reducing the negative effects of landfill leachate. This detailed review explores the origin of landfill leachate, its characteristics, global classification by age, composition analysis, consequences of mismanagement, and the important role of SDGs in achieving sustainable landfill leachate management. The aim is to provide a perspective on the various aspects of landfill leachate, covering its origin, key features, global distribution, environmental impacts from poor management, and importance of SDGs which can guide for sustainable mitigation within a concise framework.

Potentially toxic elements (PTEs) and ecological risk at waste disposal sites: An analysis of sanitary landfills

This study presents an analysis of soil contamination caused by Ni, Zn, Cd, Cu, and Pb at municipal solid waste (MSW) landfills, with a focus on ecological risk assessment. The approach aims to assess how different landfill practices and environmental conditions affect soil contamination with potentially toxic elements (PTEs) and associated environmental risks. Soil samples were collected from MSW landfills in Poland and the Czech Republic. The research included a comprehensive assessment of PTEs in soils in the context of global environmental regulations. The degree of soil contamination by PTEs was assessed using indices: Geoaccumulation Index (Igeo), Single Pollution Index (Pi), Nemerow Pollution Index (PN), and Load Capacity of a Pollutant (PLI). The ecological risk was determined using the Risk of PTEs (ERi) and Sum of Individual Potential Risk Factors (ERI). The maximum values of the indicators observed for the Radiowo landfill were as follows: Igeo = 4.04 for Cd, Pi = 24.80 for Cd, PN = 18.22 for Cd, PLI = 2.66, ERi = 744 for Cd, ERI = 771.80. The maximum values of the indicators observed for the Zdounky landfill were as follows: Igeo = 1.04 for Cu, Pi = 3.10 for Cu, PN = 2.52 for Cu, PLI = 0.27, ERi = 25 for Cd, ERI = 41.86. The soils of the tested landfills were considered to be non-saline, with electrical conductivity (EC) values less than 2,000 μS/cm. Varying levels of PTEs were observed, and geostatistical analysis highlighted hotspots indicating pollution sources. Elevated concentrations of Cd in the soil indicated potential ecological risks. Concentrations of Cu and lead Pb were well below the thresholds set by the environmental legislation in several countries. In addition, Ni concentrations in the soils of both landfills indicated that the average levels were within acceptable limits. Principal Component Analysis (PCA) revealed common sources of PTEs. The identification of specific risk points at the Radiowo and Zdounky sites contributes to a better understanding of potential hazards in landfill environments. By establishing buffer zones and implementing regular maintenance programs, emerging environmental problems can be addressed in a timely manner.

Global perspective of municipal solid waste and landfill leachate: generation, composition, eco-toxicity, and sustainable management strategies

Globally, more than 2 billion tonnes of municipal solid waste (MSW) are generated each year, with that amount anticipated to reach around 3.5 billion tonnes by 2050. On a worldwide scale, food and green waste contribute the major proportion of MSW, which accounts for 44% of global waste, followed by recycling waste (38%), which includes plastic, glass, cardboard, and paper, and 18% of other materials. Population growth, urbanization, and industrial expansion are the principal drivers of the ever-increasing production of MSW across the world. Among the different practices employed for the management of waste, landfill disposal has been the most popular and easiest method across the world. Waste management practices differ significantly depending on the income level. In high-income nations, only 2% of waste is dumped, whereas in low-income nations, approximately 93% of waste is burned or dumped. However, the unscientific disposal of waste in landfills causes the generation of gases, heat, and leachate and results in a variety of ecotoxicological problems, including global warming, water pollution, fire hazards, and health effects that are hazardous to both the environment and public health. Therefore, sustainable management of MSW and landfill leachate is critical, necessitating the use of more advanced techniques to lessen waste production and maximize recycling to assure environmental sustainability. The present review provides an updated overview of the global perspective of municipal waste generation, composition, landfill heat and leachate formation, and ecotoxicological effects, and also discusses integrated-waste management approaches for the sustainable management of municipal waste and landfill leachate.

Landfill leachate from Municipal Solid Waste: Multi-technique approach for its fine characterization and determination of the thermodynamic and sequestering properties towards some toxic metals

Landfill leachate is a multicomponent aqueous matrix generated by the percolation of rainwater into the body of a landfill. Considering its content of natural and xenobiotic components, it must be considered as a waste, whose composition depends on type of waste, biodegradation processes, rainwater, composition and compaction of waste and their age; these factors influence the transport, absorption, toxicity, bioaccumulation of the contaminants. Leachates sampled from landfill and downhill piezometers, in periods characterized by different rainfall, were studied by ATR-FTIR and SEM-EDX techniques; analyses were carried out on dried and calcinated residues obtained at T = 383 and 923 K, respectively. The chemical-physical characterization of all the leachates was carried out by using the official methods of analysis, obtaining for many metals and some organic contaminants exceedance of the concentrations with respect to the limits established by the Italian Legislative Decree 152/2006. From potentiometric titrations carried out at T = 298.15 K in NaCl(aq) and applying the Polyprotic Like model, each leachate resulted to have a different composition in terms of COOH and OH groups and various acid-base properties. The interacting ability of leachates with metal cations (Cd2+, Zn2+, Cu2+) was studied by potentiometric and voltammetric (only for Pb2+) techniques in NaCl (NaNO3 for Pb2+) aqueous solutions, at I = 0.15 mol dm-3 and T = 298.15 K, obtaining diverse speciation models and complexes of very different stability. The leachates sequestering ability towards the metal cations was quantified at various pH values using the pL0.5 parameter, proving that each leachate has a different strength of interaction towards the metals, that tends to increase with the pH and confirming that they behave as carriers of contaminants through the soil and towards groundwater, with the consequent problems of contamination and/or environmental disaster and risks for the human health.

Simultaneous ammonia and organics degradation from municipal landfill leachate by electrochemical oxidation

The two primary issues for wide implementation of the electrochemical oxidation of wastewater are the significant cost of electrode and high energy consumption. On the other side, conventional biological processes and membrane technology have several drawbacks for recalcitrant landfill leachate (LL) treatment. To address these issues, graphite/PbO2 anode was used to treat medium to mature age (biodegradability index, 5-day biochemical oxygen demand/chemical oxygen demand: 0.25) LL. To reduce the cost of the oxidation process and maximize the efficiency, operating conditions were optimized. The optimum parameter values were obtained as 24.7 mA cm-2, 180 ± 3 rpm, and 1.9 cm of current density, stirring rate, and electrode gap, respectively. Dissolved organic carbon (DOC), chemical oxygen demand (COD), and ammonia-N removal efficiencies of 55 ± 1.4%, 81 ± 1.9%, and 56 ± 3% were obtained after 8 h of degradation at optimum conditions. The decrease in aromatic substances and ultraviolet (UV) quenching materials were evaluated by UV-Visible spectroscopy and Specific UV absorbance. The conversion of aromatic compounds into simpler molecule compounds was also verified by Fourier-transform infrared spectroscopy analysis. The lab-scale anode synthesis cost was evaluated as 0.42 USD.

A review of existing methods for predicting leachate production from municipal solid waste landfills

Landfilling is one of the predominant methods of municipal solid waste (MSW) disposal worldwide, while the generation of leachate, a kind of toxic wastewater, is among the primary factors behind landfill instability and environmental contamination problems. Precise prediction of leachate production is crucial to landfill safety evaluation and design. This paper presents a comprehensive review of methods for predicting leachate production from MSW landfills. Firstly, compositional characteristics of MSW and leachate generation mechanism are analysed. Factors influencing leachate production are summarised based on the generation mechanism, including the components of MSW, climatic conditions, landfill structure, and environmental factors. Then, we classified the existing methods for predicting leachate production into four categories: water balance formula, water balance model, empirical formula, and artificial intelligence model methods. Advantages, disadvantages, and applicability of different leachate production prediction methods are compared and analysed. Furthermore, limitations in the existing leachate production prediction methods for MSW landfills and scope for future research are discussed.

A comprehensive investigation of geoenvironmental pollution and health effects from municipal solid waste landfills

This study investigates human health risks associated with heavy metals (HMs) occurrence in municipal solid waste (MSW) landfills. For testing of selected MSW landfills steps were involved, including site characterization, soil sampling and chemical testing, statistical analysis, as well as health risk assessment, carcinogenic and non-carcinogenic effects. For the Polish landfill (Radiowo) the average HMs concentrations were found in the following order: Zn (52.74 mg/kg DM) > Pb (28.32 mg/kg DM) > Cu (12.14 mg/kg DM) > Ni (4.50 mg/kg DM) > Cd (3.49 mg/kg DM), while for the Czech landfill (Zdounky): Zn (32.05 mg/kg DM) > Cu (14.73 mg/kg DM) > Ni (4.73 mg/kg DM) > Pb (0.10 mg/kg DM) = Cd (0.10 mg/kg DM). Strong positive correlations between selected HMs demonstrated identical origins. Principal component analysis (PCA) performed for the Radiowo landfill transferred the soil parameters into three principal components (PCs), accounting for 87.12% of the total variance. The results of the PCA analysis for the Zdounky landfill revealed three PCs responsible for 95.16% of the total variance. The exposure pathways of HMs for landfills were in the following order: ingestion > dermal absorption > inhalation. For both landfills, the values of hazard quotient were lower than 1, indicating no potential negative health effects. In terms of the hazard index (HI), for both landfills, no adverse human health effects occur (HI < 1). The incremental lifetime cancer risk (ILCR) values indicated negligible or acceptable carcinogenic risk of HMs (average ILCR in the range from 5.01E-10 to 5.19E-06).

Exorbitant signatures of pesticides and pharmaceuticals in municipal solid wastes (MSWs): Novel insights through risk analysis, dissolution dynamics, and model-based source identification

Studies on the occurrence and fates of emerging organic micropollutants (EOMPs) like pharmaceuticals and pesticides in MSWs are scarce in the literature. Therefore, MSWs were sampled from 20 Indian landfills and characterized for five widely consumed EOMPs (chlorpyrifos, cypermethrin, carbofuran, carbamazepine, and sodium diclofenac), physicochemical, and biological properties. The pesticide (median: 0.17-0.44 mg kg-1) and pharmaceutical (median: 0.20-0.26 mg kg-1) concentrations significantly fluctuated based on landfill localities. Eventually, principal component and multi-factor (MFA) models demonstrated close interactions of EOMPs with biological (microbial biomass and humification rates) and chemical (N, P, K, Ca, S, etc.) properties of MSWs. At the same time, the MFA resolved that EOMPs' fates in MSWs significantly differ from bigger cosmopolitan cities to smaller rural townships. Correspondingly, the concentration-driven ecological risks were high in 15 MSWs with EOMP-toxicity ranks of diclofenac > carbofuran = chlorpyrifos > cypermethrin > carbamazepine. The EOMPs' dissolution dynamics and source apportionments were evaluated using the positive matrix factorization (PMF) model for the first time on experimental data, extracting four anthropogenic sources (households, heterogeneous business centers, agricultural, and open drains). The most significant contribution of EOMPs to MSWs was due to heterogeneous business activity. Notably, the aging of soluble chemical fractions seems to influence the source characteristics of EOMPs strongly.

Health risk cause of water around landfill in hilly area and prevention and control countermeasures

Evaluating the health risks of the groundwater and surface water in landfill areas is of great significance to the health and safety of local residents. The current practice of health risk assessment is based only on the analysis results of groundwater and surface water samples, which reflect the current situation of water security in landfill areas. However, due to the neglect of risk causes analysis, thus a health risk assessment is insufficient to provide rigorous scientific countermeasures for risk prevention and control. The health risks caused by groundwater and surface water is mainly controlled by the water quality, which is comprehensively controlled by the conditions of its formation and evolution. When a landfill site is located in a hilly area, the environmental characteristics, causes, main controlling factors, and evolution processes of the surface water and groundwater in different parts of the catchment are significantly different. This study used a municipal solid waste landfill area in a hilly area as an example and defined the causes and main controlling factors of regional health risks caused by water based on an analysis of the characteristics of natural and anthropogenic factors affecting the groundwater and surface water. Then, prevention and control countermeasures were proposed for health risks caused by water in different parts of the landfill area. This study provides a method for the causes analysis and prevention and control countermeasures of health risks caused by water in municipal solid waste landfills in hilly areas.

Simultaneous production of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from recovered volatile fatty acid with treatment of leachate by Pilot-Scale Mechanical Vapor Recompression

Serious global problems faced due to many petroleum-based materials in the last century, which is called the plastic age, constitute the main motivation of this research. Considering wastewater treatment from this perspective, both the recovery of organic acids from wastewater and their conversion into bioplastics are extremely important in terms of reducing petroleum dependency. In this study, while the treatment of landfill leachate was provided with biological process integrated into Mechanical Vapor Recompression (MVR), simultaneously PHBV production was carried out with 84.9% recovered VFA as carbon source. The effects of C/N/P ratio and feeding regime on PHBV storage were investigated by Cupriavidus necator. PHBV storage of 96% (g PHBV/g DCW) was maximized by 2-stage feeding and nitrogen restriction. The ratio of 3HV to 3HB of PHBV was 45%. In addition, extracted PHBV was compared with standard PHA in terms of thermal and chemical properties with FTIR, XRD, TGA and DSC analyses.

Heavy metal contamination in soils of a decommissioned landfill southern Brazil: Ecological and health risk assessment

The incorrect disposal of waste negatively influences the population's quality of life and harms the environment. In Brazil, waste disposal in the open air is still a reality, which generates concerns about the contamination of the areas surrounding these dumpsites. The present work evaluated the possible environmental risks of a deactivated dumpsite in southern Brazil. The soil was characterized by physical and chemical tests, emphasizing the analysis of heavy metals Al, Fe, Cu, Mn, and Zn. Using geostatistical tools, it was possible to determine the distribution of these heavy metals in the influence of the landfill, since the metals Mn, Fe, and Zn showed a significant difference about the reference soil, indicating that they came from leaching from the landfill. The dispersion of the metals along the slope showed a tendency towards mobility since the highest concentrations were at elevations below the landfill. The area was considered contaminated due to the high scores of the evaluated indexes pollution, as the Improved Nemerow Pollution Index, which considers pollutant concentration, toxicity, and environmental impact to provide a measure of contamination, and was equivalent to 6.44, indicating that the area is contaminated. However, it presented low ecological risks, with a potential ecological risk of 18.55. As well as low risks to human health, with hazard index below the limit considered critical to health (HI < 1). Thus, the results of this study showed that the metals are released around the deactivated deposit, which compromises the environmental safety of the site, mainly due to its proximity to bodies of water that supply the region. Thus, the permanent control and monitoring of the areas of deactivated dumpsites are essential to avoid further pollution and should be included in the management plans for deactivating these deposits throughout the country.

Pollution characteristics and microbial community succession of a rural informal landfill in an arid climate

Informal landfills pose potential threats to the environment and human health due to the lack of anti-seepage measures. However, little research has been conducted on the distribution of pollutants in informal landfill sites situated in arid climates, as well as the underlying interaction mechanisms between environmental factors and microbial structure. In this study, we sought to investigate the pollution characteristics and microbial community succession of the landfill in northern China. The results revealed that heavy metals in the landfill showed poor mobility and migration. The lower layers of the garbage samples had higher water-soluble contents of heavy metals compared to the upper layers. The landfill-derived dissolved organic matter (DOM) was found to originate from microbial production, and four fluorescent components were identified, including fulvic acid-like substances, humus-like substances, and protein-like components. Fluorescence intensity and humification degree increased with increasing depth. The microbial diversity and richness decreased with sampling depth. The most abundant phyla in the samples were Proteobacteria, unidentified_Bacteria, Bacteroidota, Firmicutes, Myxococcota, Gemmatimonadota, Actinobacteria, and Deinococcota. As the sampling depth increased, Proteobacteria decreased, while Bacteroidota and Firmicutes showed a remarkable increase, with little variation observed in the other phyla. The partial least-squares path model (PLS-PM) results indicated that pH had the most significant effect on microbial abundance and diversity (direct effect value = -5.560), while DOM and heavy metals had the opposite effect, with direct effects of 1.838 and 3.231, respectively. DOM was identified as the driving factor for the variation in other environmental factors. The redundancy analysis (RDA) showed that the dominant genera were greatly influenced by Cu, humic-like substances, and protein-like substances. Among them, Bacillus, Alcanivorax, Devosia, and Chryseolinea may play important roles in the remediation of landfills. Our study not only gains a deeper understanding of the pollution risk of informal landfills in arid climates, but also provides a scientific basis for the future treatment and restoration of contaminated sites associated with landfills.