Study on novel type struvite precipitate for ammonium removal from landfill leachate

One significant feature of landfill leachate is the high concentration of ammonia nitrogen (NH₃-N), which led to the difficulty of subsequent biological treatment. In this experiment, chemical crystallization was applied and bittern was used as a source of magnesium. The single factor experiment was taken by changing pH, molar ratio of Mg²⁺: NH₄⁺ and PO₄^3- : NH₄⁺. Under the optimum conditions, egg shell powder and lignite were introduced into this reaction system as crystallization seed. It can be found that the crystal has a distinct precipitation orthorhombic feature through scanning electron microscopy (SEM) testing and the ammonia nitrogen removal rate has been increased to some extent after the addition of seeds. It was shown that high concentrated ammonia nitrogen in landfill leachate can be effectively removed by chemical precipitation, which made possible for subsequent biological treatment.