Abstract
AbstractLandfill leachate is characterised by high chemical and biological oxygen demand and generally consists of undesirable substances such as organic and inorganic contaminants. Landfill leachate may differ depending on the content and age of landfill contents, the degradation procedure, climate and hydrological conditions. We aimed to explain the characteristics of landfill leachate and define the practicality of using different techniques for treating landfill leachate. Different treatments comprising biological methods (e.g. bioreactors, bioremediation and phytoremediation) and physicochemical approaches (e.g. advanced oxidation processes, adsorption, coagulation/flocculation and membrane filtration) were investigated in this study. Membrane bioreactors and integrated biological techniques, including integrated anaerobic ammonium oxidation and nitrification/denitrification processes, have demonstrated high performance in ammonia and nitrogen elimination, with a removal effectiveness of more than 90%. Moreover, improved elimination efficiency for suspended solids and turbidity has been achieved by coagulation/flocculation techniques. In addition, improved elimination of metals can be attained by combining different treatment techniques, with a removal effectiveness of 40–100%. Furthermore, combined treatment techniques for treating landfill leachate, owing to its high chemical oxygen demand and concentrations of ammonia and low biodegradability, have been reported with good performance. However, further study is necessary to enhance treatment methods to achieve maximum removal efficiency.
Highlights
Urban solid waste landfills are commonly used for household, industrial nonhazardous and commercial solid wastes as well as nonhazardous sludge (Mojiri et al a)
Landfill leachate is characterised by high chemical and biological oxygen demand (COD, BOD) and often consists of high concentrations of organic contaminants, heavy metals, toxic materials, ammonia and inorganic materials as well as refractory compounds, such as humic substances (Chávez et al ) as well as contaminants of emerging concern (Eggen et al )
Alimoradi et al ( ) removed more than 90% of Al by integrated coagulation-membrane bioreactor. 99.2% of COD, 100% of suspended solids and 97.3% of total organic carbon were removed by combined coagulation and membrane (Boluarte et al ). 100% of 4-chlorophenol, 78–100% of oxidation intermediates from wastewater by integrated catalytic oxidation and adsorption (Arsene et al )
Summary
Urban solid waste landfills are commonly used for household, industrial nonhazardous and commercial solid wastes as well as nonhazardous sludge (Mojiri et al a). Sanitary landfilling continues to be employed in waste management plans despite its potentially hazardous effect on the environment (Mojiri et al ). Waste may undergo a series of biological and physicochemical transformations after being landfilled, thereby producing extremely polluted wastewater called leachate. Such wastewater may pollute nearby ground and surface water as well as soil (Zamri et al ). Ecological pollution and health issues are commonly connected to the insufficient treatment of landfill leachate (Mojiri et al a)
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