The increase in the generation of waste is a reality and the landfills do not stop filling up, producing in them a mixture of different waste such as, for example, decomposing organic matter, leftover detergents, other liquids and oxidized metals, among others. This mixture causes a by-product to be generated in the form of a liquid, called leachate, which is found circulating through the rest of the waste. These leachates have serious consequences, mainly because they cause contamination of streams and groundwater . That is why it is so necessary to reduce and recycle waste, in short, to do a good management of it to avoid the increase of leachate. In addition, it is also important to have methods to treat them.
If you want to know more about leachates and about the treatments used to control them, continue reading this interesting AgroCorrn article in which we talk about the definition of leachates, examples and their treatment .
- What are leachates and leaching – definition
- Leachate: examples
- Leachate treatment
What are leachates and leaching – definition
Leachates are the liquids that circulate among the waste found in landfills. The leaching process occurs during the fermentation and decomposition of organic matter, as a consequence of the filtration of water from the rains that seep through the waste and carry chemical compounds and biological materials. They are very polluting and a danger to the environment and the health of living beings, that is why they must be treated correctly.
The quality of these in a landfill depends on the time it is in them and the type and quantity of waste that is had. For example, the quality of leachate from a developed country is not the same as one that is still under development, since, in developed countries, there is waste management (recycling) that prevents more volume of waste from reaching landfills. However, most developing countries do not have good waste management.
Did you know that worms produce a nutrient-rich leachate, also called worm castings , while breaking down organic matter? Well yes, also thanks to its concentration in nutrients it is used as a fertilizer for cultivation. Although it is 100% natural and non-toxic, it is composed of a large amount of minerals and nutrients, so it is important to dilute it before use, since its high concentration could be harmful to plants.
Therefore, mainly, as examples of leachates, we can distinguish between two types:
- Landfill leachates: liquids that circulate between landfill wastes and are given by the leaching process when decomposition and fermentation of these occurs.
- The leachate of worms: liquids produced in a totally natural way by these animals in the earth and the subsoil when they feed on organic matter and decompose it.
All polluting liquids in landfills must be treated before being dumped onto a surface. In the treatment process, the characteristics of the leachate must be taken into account, as well as the location of the landfill. Well, leachates from a new landfill do not receive the same treatment as those from a landfill that has been exploited for a long time, or from a RNP landfill or hazardous waste . To carry out the treatment to avoid contamination by leachates , its characteristics must be taken into account, as well as the location of the landfill.
As we have mentioned before, the leachates are stored in ponds before their final treatment, these differ depending on the type of landfill. The hazardous waste sites (RP) are deposited on rafts which must be waterproofed with polyethylene to prevent leakage, leachate from landfills nonhazardous waste (RNP) are collected in concrete rafts.
The technology to treat leachates are as follows:
Heat treatment (evaporation)
In this, the energy of the biogas generated in the landfill is used to evaporate the leachate. This technology controls leachate emissions and, finally, a sludge remains that is deposited back into the landfill. Here you can learn more about what evaporation is .
Aerobic or anaerobic treatments can be chosen, depending on the characteristics of the leachate. Aerobic biological treatments consist of using microorganisms in the presence of oxygen and agitation, to purify the organic compounds present in the leachate. On the other hand, the anaerobic process has the same principle, although the microorganisms are in conditions characterized by a lack of oxygen.
The technology using membranes is used more and more frequently, and is being included for the treatment of leachate. The applications that occur are the following: ultrafiltration, reverse osmosis, microfiltration, nanofiltration and direct osmosis.
This treatment removes coagulant particles, that is, metal salts and polyelectrolytes. Coagulation, flocculation and sedimentation processes are involved. Treatments are classified into chemical precipitation, reverse osmosis, NH3 stripping, chemical oxidation, and activated carbon absorption.
Some systems that can function naturally, such as lagoons or wetlands, are proposed for the management of leachates, as an alternative to the other treatments, and placing them where it is necessary artificially so that they then function naturally. However, with these systems a large amount of territory is required for the processes.
Learn more about leachate and its contamination with this other AgroCorrn article in which we talk about Garbage Pollution: causes and consequences .
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