Potential toxicity of leachate from the municipal landfill in view of the possibility of their migration to the environment through infiltration into groundwater

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.

The influence of combined treatment of municipal wastewater and landfill leachate on the spread of antibiotic resistance in the environment - A preliminary case study

Environmentally-friendly management of landfill leachate (LL) poses a challenge, and LL is usually co-treated with municipal wastewater in wastewater treatment plants (WWTPs). The extent to which the co-treatment of LL and municipal wastewater influences the spread of antibiotic resistance (AR) in the environment has not been examined to date. Two WWTPs with similar wastewater composition and technology were studied. Landfill leachate was co-treated with wastewater in one of the studied WWTPs. Landfill leachate, untreated and treated wastewater from both WWTPs, and river water sampled upstream and downstream from the wastewater discharge point were analyzed. Physicochemical parameters, microbial diversity, and antibiotic resistance genes (ARGs) abundance were investigated to determine the impact of LL co-treatment on chemical and microbiological contamination in the environment. Landfill leachate increased pollutant concentrations in untreated wastewater and river water. Cotreatment of LL and wastewater could affect the abundance and diversity of microbial communities and the interactions between microbial species. Co-treatment also decreased the stability of microbial co-occurrence networks in the examined samples. The mexF gene was identified as a potential marker of environmental pollution with LL. This is the first study to explore the impact of LL on the occurrence of AR determinants in wastewater and rivers receiving effluents.

Concentration of heavy metals in leachate, soil, and plants in Tehran's landfill: Investigation of the effect of landfill age on the intensity of pollution

Heavy metals are one of the important pollutants in landfill leachate. Plants and soil near the landfill may be contaminated by leachate. In this study, by evaluating the heavy metals in the leachate of two landfills and the soil and plants near them, the amount of pollution caused by the leachate in the environment around the landfills in Tehran was investigated. This study was conducted in three stations, soil and plant samples were prepared according to a specific protocol. Also, three indexes including PI, PI_Nemerow, and BF were used to interpret the results. The results showed that the concentration of total metals in the old landfill leachate and new landfill leachate was only 12% different and was 24.13 mg/L on average. In the new landfill leachate, iron had the highest concentration among metals, which was 22.94 and 17.01 mg/L in two samples. In the old landfill leachate, the concentration of manganese was 15.71 mg/L, which was the highest among the studied metals. The concentration of heavy metals in the soil of the old landfill was 24.6% lower than the concentration of metals in the soil of the new landfill. In all samples, the highest metal concentration in the soil was related to manganese, which was 33.65-34.14 mg/L. Cadmium had the lowest concentration in soil compared to other metals. The concentration of total metals in the studied plants was 29-60 ppm. The PInemerow for studied stations was 0.1711, 0.1708, and 0.1463. The highest PI in the case of lead was observed at the second station equal to 0.54. The highest BF in case of Atriplex Undulata was more than 6 and related to cadmium, while the highest BF in case of Atriplex Cinearea was more than 3.5 related to cadmium. This study showed that the soil and plants of the landfill were contaminated with heavy metals under the influence of leachate, and the ability of plants to uptake and accumulate metals can be used to manage soil pollution near the landfill.

Modeling leachate generation: practical scenarios for municipal solid waste landfills in Poland

The idea of water balance calculations within the landfill is to determine the distribution of water input and output, and finally the volume of leachate generated. The scope of this data is essential for rational planning of water and wastewater management, and designing leachate drainage network and leachate treatment systems. The aim of this study was to assess the possible amounts of leachate generation regarding ten different scenarios of landfill sealing systems. The calculations were performed using the Hydrologic Evaluation of Landfill Performance (HELP) model. It was revealed that the greatest share among the components of water balance in the landfill has precipitation (on average 509 mm in the 5-year period of simulation), together with evapotranspiration (on average 391 mm in the 5-year period of simulation). The study shows that the minimum amount of leachate (797-803 m³/year) occurs when the best placement quality (=5) is regarded for the geomembrane installed in the bottom of the landfill. The maximum leachate generation (830 m³/year) was found for those scenarios in which only three layers of bottom sealing systems were adopted, with the worst placement quality (=1) assigned to geomembranes. The results of this study confirm that the application of multilayer sealing systems has visible impact on the reduction of leachate generation of around 33 m³/year.

Identification of Groundwater Pollution Characteristics and Health Risk Assessment of a Landfill in a Low Permeability Area

The shallow weathering fissure groundwater in the red-bed area of Southwest China is usually the only drinking water source for most rural residents. In this study, a typical landfill with surrounding residents drinking unpurified groundwater in red-bed area was selected and water quality detection, groundwater numerical simulation and human health risk assessment were used to identify and assess groundwater pollution in the region. The chemical type evolved from HCO₃-SO₄-Ca-Mg and HCO₃-SO₄-Ca to Na-Ca-Cl-HCO₃ contaminated by the landfill. Na⁺ and Cl⁻ were selected as factors for rapid identification of groundwater pollution. Subsequent analyses using these factors showed that the leachate pollution plume boundary was 190 m downstream of the landfill. Analysis of the redox conditions revealed that the area from the landfill to 5 m downstream was the reduction zone, while the area beyond 5 m was the oxidation zone. The migration and attenuation patterns of inorganic salts (such as SO₄²⁻) and heavy metals (such as Fe and Mn) in the oxidation and reduction zones differed obviously. Meanwhile, the organic pollutants in the leachate were reduced and decomposed into organic acids, which caused the groundwater 80 m downstream of the landfill to become weakly acidic (pH ranged from 6.51 to 6.83), and promoted re-entry of adsorbed heavy metals (such as Pb) into the groundwater. The groundwater risk assessment based on human health revealed that lead, manganese, chlorobenzene, dichloroethane and chloroform constituted a major health threat to the residents. The rank of non-carcinogenic risk was lead >manganese, and the maximum area of non-carcinogenic risk was 15,485 m². The total carcinogenic risk caused by organic pollutants was 7.9 × 10⁻⁶, and the area of the carcinogenic risk zone was 11,414 m². Overall, the results of this study provide a scientific basis for management of drinking water and groundwater remediation in the red-bed area with low permeability.