| The landfill leachate is hazardous and difficult to be treated. The present methods are mainly: physical-chemical process, biological process and land treatment. All of these methods can not remove pollutions thoroughly and effectively. Cavitating water jets has the merit of strong cavitating ability. Some scholars have applied it to the purification of wastewater, but no research has been carried out on waste leachate with cavitation technology up to now.Based on present research and the drawbacks of previous waste leachate treatment methods, the paper applied the cavitating water jets to puritify landfill leachate. We take landfill leachate from a sanitary landfill in Chongqing as research object, and we has researched the mechanism of treatment respectively by cavitating water jets, coagulation, coagulate-adsorption and chemical precipitation method. This thesis studied the chang law of COD and NH3-N impacted by some factors (pumping pressure, confining pressure, cavitation time and pH) and some influencing factors (coagulation method, coagulate-adsorption method and chemical precipitation method), and studied some chnological parameters of subsequent treatment. Through the research above, following six conclusions are drawn:(1)Cavitating process of cavitating water jets is effective to landfill leachate puritification. The complex macro-moleculeorganic organic matter of landfill leachate can be degraded to the small molecular organic matter after the cavitation.(2)After cavitating treatment, the water quality condition of landfill leachate can be coagulated easier. Compared with landfill leachate which is not be treated, coagulation effect of landfill leachate treated with cavitation is better under the same condition of coagulation.(3)The optimal cavitation condition is obtained: investigated pH 9.0, confining pressure 0.6MPa, cavitation time 15times, pumping pressure 10Mpa, under this optimal cavitation condition, COD can increase to 124.8%, BOD5/COD and SS are improve by 52.44% and 191.5% respectively, and the removal rate of NH3-N is 57.32%.(4)Coagulation treatment is carried out after cavitating treatment. The optimal coagulation condition is obtained following: PFS dosage 1100mg/L, pH 5.5, PAM dosage 2.5mg/L, under this condition, the removal rate of COD, SS, and NH3-N can reach 85.13%, 9.024% and 89.04% respectively. (5) Coagulate-adsorption treatment is after coagulate treatment. The optimal coagulate-adsorption treatment condition is obtained: the dosage of PFS, PAM and activated carbon is 450mg/L, 1.2mg/L and 5.0g/L respectively, pH 7.5, the additional time of activated carbon is 60 seconds after quick-stir, and the slow-stir time is 40 mins after adding activated carbon, under this condition, the removal rate of COD, SS, and NH3-N can reach 68.63%, 20.55% and 91.54% respectively.(6)The last stage is chemical precipitation treatment. MgO and H3PO4 are used as precipitation reagent. The optimal condition of chemical precipitation treatment is obtained: Mg2+:PO43-: NH4+=1.3:1.15:1, pH 9.0, reaction time 20min, precipitation time 30min, under this condition, the removal rate of COD, NH3-N and SS is 19.34%, 92.41 and 89.29% respectively. After the chemical precipitation treatment, COD, SS, and NH3-N is 292mg/L, 3mg/L and 22mg/L respectively. The result of treatment can meet the second emission standard for wastewater discharge.The innovation of this paper is applying cavitating water jets to treat landfill leachate. By researching, the paper introduces a new landfill leachate treatment method, and this method has great theoretical and practical guide value to organic wastage which is difficult to been treated.
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