Remoção de nitrogênio amoniacal de lixiviado de aterro de resíduos sólidos por precipitação química com formação de estruvita / Ammonium-nitrogen removal from leachate of solid waste landfill by chemical precipitation with struvite formation




Municipal solid waste landfilling is the best final disposal method due to its low operating cost and minimizing environmental impacts. As a result of degradation of the solid waste, leachate is generated and it is characterized by high concentrations of organic matter, ammonia nitrogen and inorganic salts which has high pollution potential. In this context, the present research aimed to evaluate the physical-chemical treatment by chemical precipitation for the removal of ammonia nitrogen in the form of struvite. The bench scale experiments were conducted using Jar Test equipment. The methodology was to investigate the factors that interfere in the reaction conditions for chemical precipitation of struvite, as the sequence of addition of reagents, the optimal molar ratio and the influence of order of addition of reagents and pH adjustment. After these steps to evaluate the chemical precipitation in trials with raw leachate. According to the results the best ammonia nitrogen removal was 85.6%, when MgCl2.6H2O and Na2HPO4.12H2O combination was used, with an excess of 1.5 times the molar concentration of magnesium ion. The feeding sequence followed phosphorus and magnesium reagent, and finally pH adjustment to the value of 9 with 6N NaOH. Following the same conditions, but using MgO + 85% H3PO4 combination, the removal was quite low but equal to 76.3%. The experiment proved that chemical precipitation is a pre-treatment viable for the raw leachate studied.


residuos solidos, domesticos e industriais struvite estruvita precipitação química resíduos sólidos solid waste raw leachate chemical precipitation lixiviado bruto

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