Removal of ammonia and COD from leachate by MAP precipitation method and contribution of natural materials

The objective of this study was to examine the preliminary treatment of landfill leachate by magnesium ammonium phosphate (MAP) precipitation. For this purpose, the optimum conditions for ammonia and chemical oxygen demand (COD) removal have been investigated. In MAP precipitation, experiments, various stoichiometric ratios were tried to provide the best ammonia removal efficiency. The maximum ammonia removal was found to be 80% at pH 9.5 and Mg:NH4:PO4 molar ratio of 1:1:2.5. As a result of the study, the feasibility of the MAP process was evaluated and the application principles of the process were defined. Then, the contribution of natural materials to the MAP precipitation was examined. For this purpose, zeolite, sepiolite and diatomite were added to the system at a dose of 2 g/L. Ammonia and COD removal was increased by about 10%, while no significant difference was observed between natural materials. Experimental data were also evaluated by statistical methods and the regression equations of ammonia and COD removal were obtained using Minitab 16 statistical software.