The Treatment Of Landfill Leachate By Flocculants And MAP Methods

The reaction time of the coagulation-MAP method is short, The method didn't need to control special conditions. The process is simple, the equipments investment are cheap, power consumption is small and operation is convenient. The method also has a good effect on removing the ammonia, and the coagulation producing sediment is uesd widely. So the coagulation-MAP method receives people's wide attention in the aspect of landfill leachate pretreatment. The study adoped the coagulation-MAP method to treat the landfill leachate. The experiment studied the method treating landfill leachate mechanism and its process conditions systematically. It also investigated the removal rules of COD, SS and ammonium in the water samples. The study provided a technical support for the method treating the landfill leachate.The main research contents included:â‘ T he choice of flocculation medicament with treatment of landfill leachate by flocculation method;â‘¡The research of single factor influence and orthogonal experiment with treatment of landfill leachate by flocculation method;â‘¢The choice of medicament combination with treatment of the water(landfill leachate by flocculation method) by MAP method;â‘£The research of single factor influence and orthogonal experiment with treatment of landfill leachate by flocculation and MAP method.⑤analyzed the experiments product and feasibility of the settling uses in the fertilizer.The paper used PAC, PFS and PAFC as the flocculation medicament with treatment of landfill leachate by flocculation method and then comparing the experiment result, with adding PAFC least in the landfill leachate, COD and SS was removed effectively; with comparing the experiment result, PAFC response production's cotton wool body is dense and quicker the settling rate, is more advantageous of the landfill leachate spate separation.The influence of dosage of PAFC, dosage of PAM, reaction time, pH value and precipitation time on the treatment effect of landfill leachate was discussed during single factor and orthogonal experiment and then through the orthogonal experiment to determine the optimal reaction conditions were that under the room temperature condition, first stirs 1min by the 150r/min mixing speed, then responds 25min by the 50r/min mixing speed, PAFC dosage was 1300mg/L, PAM dosage was 5mg/L and pH was 5.5, precipitation time was 35min.When Na₂HPO₄·12H₂O and MgCl₂·6H₂O combination was used to treat the landfill leachate which was coagulated and precipitated, the removal rates of ammonia nitrogen was 85.13%; Aslo, when Na₂HPO₄·12H₂O and MgSO₄·7H₂Ocombination, H₃PO₄ and MgO combination was used to treat the same landfill leachate, the removal rates of ammonia nitrogen were respectively 83.01% and 83.27%. Therefore, Na₂HPO₄·12H₂O and MgCl₂·6H₂O combination was determined to the best reagent combination. The study was investigated the influence factors on the landfill leachate treatment effect by single factor experiment, such as the reagent moore dosing ratio, pH, reaction temperature, reaction time and precipitation time. The best experiment conditions of coagulation-MAP method was determined by the orthogonal experiment. Under the room temperature conditions: The pH was 8.5, the reagent moore dosing ratio of Mg²⁺: NH⁴⁺: PO₄^3- was 0.9: 1: 1.2, the stirring speed was 100r/min, reaction time was 25min, and the precipitation time was 35min.The components of the sediment were analysed, the contents of P₂O₅(29.6%), N(5.6%) and MgO(17.8%) in the sediment was closed to the percentage of nutrient factorof the theoretical MAP. The X-ray diffraction showed the sediment spectrogram was very closed to the standard spectrogram. The sediment had good crystal morphology by scanning electrometry microscopy, and the microscopy was similar to the theoretical microscopy (diamond, inclined square). The observation results show ed that most of sediment were the MAP deposition.Through further intensify the MAP of recycling and used to strengthen the development of controlled-release fertilizers in practical engineering, can have wide application and promotion.The coagulation-MAP method treating the landfill leachate has a significant effect, simple operation, and higher effects on COD, ammonia and SS. The method has laid a good foundation for follow-up biological treatment. Through further intensifying recycle the MAP, the method could realize to be widely application and promotion in the practical engineering.