Research On The Combined Technology Of "tertiary Garbage Packed Bed + Ozone Method + SBR Method" For Leachate From Domestic Waste Landfills

There are some high concentration pollutants in the landfill leachate. And water quality and quantity are changed frequently. It will cause serious pollution to the surrounding environment if it is not treated properly. Moreover, the landfill leachate easily appears the aged characteristics:refractory organics is more than before, and the biodegradability is very poor (BOD/COD=0.1). It is difficult that this kind of wastewater is efficiently treated with the traditional landfill leachate treatment technology.In this study, Landfill leachate from Kunming Donjiao landfill leachate is experimented by the " three-phase refuse filler bed+ozone oxidation method and activated sludge treatment" process; During the experiment, the treatment effect and the influence factors ofthe each process unit are not only studied, but also the treatment effect and main the influence factors of the combination process are studied.The main results are as follows:There are the aged characteristics(landfill time is more than10years) in the leachate from Shanghai Laogang landfill. The water quality indicators are as follows:COD:5000-110000mg/L, BOD:440-830mg/L, NH3-N:900-1200mg/L, pH:7.4-8.6. The optimum operation parameters and the best effect are studied in the process of the refuse filler bed, ozone oxidation and biological methodand the joint process.(1) The removal rate of COD、BOD5、NH3-N, and E. coli were83.9%、99.9%、97%and91.6%. When the landfill leachate was treated by three level refused filling bed. Through three-phase garbage packed bed, high concentration of refractory organics was greatly reduced; wastewater in the entrance is dark brown, and the effluent are light yellow in color; BOD5/COD is close to zero, which indicates that the packed garbage bed can efficiently remove pollutants; but it is very difficult to directly remove the organic pollutants from landfill leachateby biological treatment once more after the refuse filler bed treament.(2) The effluent was treated by ozone method after the refuse filler bed treatment.when the ozone concentration is262mg/L, The rate of CODwas reduced from318mg/L to179mg/L; chroma was reduced from56degrees to3.15degrees; but the BOD5concentration was increased from the original6mg/L to84mg/L. Therefore, the rate of BOD5/COD is increased to0.5; The biodegradability of the landfill leachate is improved greatly. It is showed that the ozone oxidation can not only decrease the COD concentration and chroma in the landfill leachate greatly, but also improve the BOD concentration.So the biodegradability is improved effectively.(3) When the ozone concentration is235mg/L, the COD concentration of the effluent treated by activated sludge process was92mg/L; when the ozone concentrationwas increased to262mg/L, the COD concentration was75mg/L, coming up the newest emission standard ofthe landfill leachate (GB16889-2008).(4)The effluent was treated by activated sludge process after ozone oxidation. Test results are as follows:①In addition, the COD concentration ofthe effluent is higher than that of theory. It indicates that there are still some toxic substances that reduce the efficiency of biological treatment of leachate after ozone oxidation.②When TN/BOD>1, the nitrification process may have an effect on COD removal; When the NH3-N concentration exceeds50mg/L, the removal rate of the COD decreases rapidly;③The COD concentration of the effluent was81+3mg/L when the phosphorus concentration changed between0to2(mg/L). Therefore, the phosphorus source is not the key factor which affects the COD concentration of the effluent.④The carbon source increased can enhance microbial activity, thereby promoting the microbial adsorption to some non-degradable material. The final effluent still contained some pollutants that could not be degraded or adsorpted by activated sludge.It is showed that: The garbade packed bed can effectively degrade the refractory organic pollutants, NH3-N and chroma; The COD concentration and chroma was reduced and the BOD concentration is improved. So the biodegradability was increased to a certain exten after the wastewater is treated by the ozone oxidation; the final effluent which was treated by the "three refuse filler bed+ozone oxidation method and biological" combined process could meet the newest national discharge standard (GB16889-2008). Therefore, it is significant that landfill leachate is treated by the combined process for practical engineering application.