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Los leachate And the environmental problems these pose are a consequence of our societal model, in which waste generation is increasing year after year worldwide. According to a United Nations reportIt is expected that only the urban solid waste increase from 2.300 billion tons in 2023 to 3.800 billion in 2050. This increase in waste will lead to higher spending on its management and on hidden costs such as pollution, unsanitary conditions and climate change caused by its generation and accumulation. In addition, it will increase concerns about leachate as its generation increases.
Although the collection and storage of waste is usually carried out in controlled landfills that comply with current regulations, generate localized pollution that can be dangerous for nearby ecosystems. One of the consequences of this localized accumulation of waste is the generation of leachate. Leachate is liquid substances generated by landfill waste and circulating through it. Its appearance is unpleasant, appearing as a dense liquid of black or yellow color, sometimes with foam, and with a bad odor.
How do these substances form? What is leaching?
These liquid substances can form through the leaching of rainwater, residual liquids present in the waste, or liquids derived from decomposition. These liquids end up circulating among the garbage, carrying both biological and chemical materials, mixing with solvent residues, and promoting the oxidation of certain metallic materials. As the water passes through and leaches the mixture of materials present in the landfill, its The composition ends up being highly variable.because it depends on the waste present, the composition of the soil, and the amount of rainfall.
Why are leachates so dangerous?
The danger of leachate stems from the components that can generate it, as these are considered hazardous and highly polluting wasteTherefore, mismanagement can lead to serious penalties. Leachate can contaminate soils, causing degradation and endangering biodiversity, as well as water sources when it reaches rivers, lakes, seas, or seeps into groundwater. This water can be the source of drinking water for many populations and living beings, so contact with leachate poses a threat to their health.
How to minimize the impact of leachate?
One way to minimize its impact is by limiting its proliferation through correct waste management (Separating waste so that it can be properly recycled). This reduces the amount of waste going to landfills, as well as the pre-treatment of polluting liquids before they are dischargedThis type of action causes the leachate from a developed country and a developing country to be different, since the former have a better management system.
Once generated, Leachate is considered a complex effluentBecause its treatment is complicated due to the high concentration of pollutants, landfills must have equipment for collecting, storing, and treating leachate. On the one hand, to protect the soil, different layers can be used to limit infiltration and impact, such as vegetation and natural soil, or even synthetic materials to create an impermeable layer.
Once the leachate has been collected, if it is a hazardous waste (HW) landfill, the leachate is placed in impermeable ponds before treatment, and if it is a non-hazardous waste (NW) landfill, a concrete pond is sufficient. Once collected, treatment is initiatedA process where the following alternatives stand out:
- EvaporationThermal treatment using energy to evaporate the leachate; the remaining solid (sludge) is returned to the landfill.
- Biological: Through anaerobic treatment (microorganisms that digest organic matter in the absence of oxygen), or aerobic treatment (microorganisms that need oxygen to be able to carry out digestion), the organic matter present in the leachate is eliminated.
- Membranes: Used to separate the different compounds that make up the leachate through ultrafiltration, microfiltration, nanofiltration and osmosis.
- Physicochemical treatment: Use coagulants and flocculants to remove certain compounds from the leachate through sedimentation.
