Experimental study on MAP recycling in landfill leachate

The landfill leachate was treated by magnesium ammonium phosphate (MAP) precipitation method. A series of single factor influence tests were conducted and the influence of these factors to MAP precipitation was analysed in this paper. The results showed that the optimum condition of MAP recycling were as follow: the best reagent was MgCl₂·6H₂O, the best pH value was 10, the best proportion of reagents was n(Mg) :n(N) :n(P)=1.2:1:1.2. The removal rate of NH₃-N could reach up to 96.65% under the optimum condition. In the precipitate, the content of As, Cr, Hg, Pb, Cd didn´t exceed the maximum concentration of national standard of organic-inorganic compound fertilizer, the MAP could be used as slow release fertilizer directly.