Sequential treatment for stabilized landfill leachate by ozonation–adsorption and adsorption–ozonation methods

Abstract

This paper investigates the potential use of sequential treatment using ozonation–adsorption and adsorption–ozonation processes for stabilized landfill leachate treatment. Zeolite was used as adsorbent due to its novel composition of naturally hydrated aluminosilicate minerals. Preliminary tests were conducted to determine the optimum conditions of ozone and zeolite. Results demonstrated that the usage of ozonation as a post-treatment for adsorption could effectively remove 92%, 82%, and 75% of colour, COD, and NH4–N, respectively. In addition, the application of ozonation as a pre-treatment showed a good removal for colour, COD, and NH4–N with a removal efficiency of 93%, 80%, and 71%, respectively. Also, an improvement in biodegradability of the leachate was achieved after ozonation/adsorption and adsorption/ozonation which increases the BOD5/COD ratio from 0.016 to 0.195 and 0.194, respectively, where the maximum BOD5/COD in the raw leachate was 0.02. This is attributed to the oxidation of high molecular weight organics in the sample. A combined treatment leads to a removal of inorganic and small non-biodegradable organic molecules, which decreases the COD and further improve the BOD5/COD ratio. This study demonstrates that the application of ozonation as a pre- and post-treatment with zeolite is an effective treatment method that can improve the treatment of stabilized landfill leachate .