Technologies for Treatment of Landfill Leachate: A Brief Review

Abstract: Landfill leachate contains organic compounds like amines, ketones, carboxylic acid, alcohols, aldehydes, phenols, phosphates and inorganic pollutants such as ammonia, phosphorous, sulphate, emerging contaminants like per-and polyfluoroalkyl substances (PFAS) and also the toxic heavy metals like Mn, Cd, Pb, Fe, Ni, Zn and As. In young landfill leachate, the concentration of volatile acid and simply degraded organic matter is high while pH is low. However, in mature landfills, there is more leachate production with high pH. The age of landfill and determination of parameters like BOD, COD, COD/BOD ratio are important to know the appropriate treatment methods. Physicochemical, biological and combined methods are the most reported landfill leachate treatment methods. Advanced oxidation process, adsorption, coagulation-flocculation, bioremediation, phytoremediation, bioreactor, membrane process and air striping are some of the common categories of effective treatment of landfill leachate. For better apprehension, it has been reviewed that treatment efficiencies of different kinds of leachate depend on their composition and method adopted. Studies related to the removal of organic matter and heavy metals are predominant which reported excellent removal efficiency ranging from 80-100%. In addition, physical parameters like color and turbidity can also be removed effectively using appropriate treatment methods. The present article deals with a concise review of existing literature on sustainable landfill leachate treatment technologies which include physical, chemical, biological and combined techniques.