Study On Physicochemical And Biochemical Intensified Pretreatment Of Landfill Leachate

Urban waste disposal problem has become increasingly prominent, with the accelerated process of urbanization and rapid economic development. As sanitary landfill as a waste of key technology in our country, leachate generated damaging to the environment is increasing. Because leachate is the water that quality changes largely, high CODCr and ammonia concentration, poor biodegradability, higher concentration of toxic and hazardous substances in the characteristics of landfill leachate, its treatment is internationally recognized as difficult. With the " Pollution control standard of living solid waste landfill " (GB16889-2008) promulgated and puts into practice, so that our handling of the leachate with higher demands. Study on landfill leachate treatment process and improve the performance of leachate treatment to meet new emissions standards, become a difficult subject that must be faced and solved.This paper has summarized the leachate treatment technology research results and lessons learned that, in the treatment of landfill leachate was first to remove high concentrations of nitrogen components, and then remove organic matter. In this experiment, used Chang Sheng Qiao landfill leachate as research object, used MAP chemical precipitation and hydrolytic process of ASBR to pretreat landfill leachate. MAP chemical precipitation can remove most of the ammonia landfill leachate, removal of part of the organic compounds, and adjust carbon and nitrogen ratio of leachate, reduce the load on the follow-up process; then improve the biodegradability of effluent through hydrolysis and acidification process.In MAP chemical precipitation stage, compared the effect of different agents on ammonia nitrogen removal in landfill leachate, investigated solution pH, reaction time, molar ratio of reactants factors, and by orthogonal regression analysis the impact of various factors to the experimental results, guides reaction and determine the optimal experimental conditions. Finally, use MgO and NaH2PO4 as MAP chemical precipitation precipitation agent. Optimal experimental conditions: pH = 9.5, reaction time 60min, n (Mg): n (N): n (P) = 2.5:1.0:1.2, then the removal rate of ammonia nitrogen was 91.92%, residual phosphorus content of 25.0mg/L, removal rate of CODCr was 10%; by regression orthogonal experiment: Regression equation of ammonia nitrogen removal rate: Y1=87.57-1.46X1-1.22X2-1.07X3+0.55X1X2-0.16X1X3+0.21X2X3; Regression equation of residual phosphorus: Y2= 221.43+35.401X1+191.19X2-2.10X3+33.04X1X2-3.36X1X3-1.60X2X3;By scanning electron microscopy and X diffraction characterization experiments showed that the main component of precipitate obtained is struvite, when under the optimal process parameters.Researched the hydraulic retention time (HRT), influent pH, volume loading etc. parameters at hydrolysis and acidification phase. The results show that:â‘ water in the reactor increased with HRT, CODCr removal rate is also improved accordingly, but with the extension of HRT, the concentration of NH3-N in waste water have shown a trend of increase, and negative growth at an increasing rate. Therefore, the HRT of hydrolysis and acidification can not be too long, in order to avoid NH3-N concentration increases too much, and impact follow-up aerobic biological treatment. Combined to consider the water BOD5/CODCr of effluent, the best HRT of hydrolysis and acidification is 48h, and the BOD5/CODCr increased by 11%.â‘¡Adjust water pH value of 6.0 ~ 7.5, the system pH values stabilized at 7.36 ~ 8.38, CODCr removal rate remained at between 23.56% ~ 13.15%. In which the influent pH value adjusted to 6.0, CODCr average removal rate of up to 23.56%, and the BOD5/CODCr increased by 13%.â‘¢water volume loading in the 2.05 ~ 12.67kgCOD/(m3?d) when, CODCr removal rate remained at between 34.13% ~ 13.53%, indicating that hydrolysis and acidification process has strong resistance to impact load.In this study, used MAP chemical precipitation + hydrolysis and acidification process of ASBR to pretreat landfill leachate, effluent NH3-N concentration <200mg/L, CODCr removal efficiency>25%, and BOD5/CODCr of effluent has more than 10% increased compared with the influent, research shows that the pretreatment process on the landfill leachate has good treatment effect.