What is Leachate?
Leachate is a highly polluted liquid generated from water percolating through a solid waste disposal site, accumulating contaminants, and moving into subsurface areas. Another source of leachate could be the high moisture content of certain disposed wastes.
How is Leachate Formed?
Leachate is an amalgamation of water filtering downwards through a landfill, extracting soluble or suspended materials from the putrefying waste.
Where does Leachate go in a Landfill?
The leachate from landfills may infiltrate groundwater aquifers due to rainfalls, converge towards the nearby river system by groundwater flow, and pollute the surrounding environment.
Why is Leachate Harmful to Soil and Water?
Leachate coming out from sanitary landfills is one of the important groundwater pollutants. The liquid contains toxic contents, organic or inorganic chemicals, and pathogens; it can pollute the groundwater and therefore represents a health risk. The excess quantity of heavy metals in the leachate may cause significant damage to the land and human health due to its mobility, solubility, and ability to mix with water or absorbed by plants.
Treatment of Leachate
Leachate treatment is divided into biological treatment, physicochemical treatment, or a combination of both.
Biological treatment is performed using sequencing batch bioreactors, membrane bioreactors, aerated lagoons, and up-flow anaerobic sludge blanket reactors. Whereas, physicochemical treatment involves the use of flocculation-coagulation, adsorption by activated carbon, chemical precipitation, ion exchange, and chemical oxidation.
Treatment using the combination of both is an efficient and more suitable way as the procedure considers the leachate age, season, climatic conditions, regulation criteria, and pollutants concentration.