Study On Ozone Oxidation Process Of Refractory Landfill Leachate

Landfill treatment of domestic garbage will produce refractory landfill leachate with complex components.It is harmful to the environment and human health.In this thesis,young and mature landfill leachates were selected,and their organic characteristics were characterized.Two aeration methods,sand core and ceramic membrane,were used for ozone oxidation of landfill leachate of different ages,and the oxidation efficiency of two aeration methods on organic matter was researched.The effects of ozone concentration,p H value and COD concentration on organic matter treatment were investigated,and the degradation process was analyzed.The main of main of our work and conclusions are follows:（1）The significant characteristic of the organic matter in the young leachate was the high content of biopolymer component.Most of the biopolymer component was decomposed by ozonation and some of humic-like organic matter was generated simultaneously.However,only low removal rates（<10%）of the total organic carbon（TOC）was observed.The small molecular weight humics-like acid with heterocyclic structure containing nitrogen was the component that difficult to be decomposed at low ozone dosage.（2）Compared with sand core aeration,ceramic membrane aeration had higher ozone utilization rate and organic matter removal efficiency.When the reaction time was 120min,the removal rates of TOC,COD,UV₂₅₄ and chromaticity of the first-stage aged landfill leachate were 20.5%,25.56%,68%and 94%respectively.The removal rates of TOC,COD,UV₂₅₄ and chroma of the second stage landfill leachate were 11.2%,26%,70%and 97%respectively,which were higher than those of sand core aeration.Therefore,under the same conditions,ceramic membrane aeration was more effective for organic matter degradation.Except TOC removal rate,organic matter removal rate of second-stage landfill leachate were higher than that of first-stage aged landfill leachate.Ozone oxidation system can significantly improved the molecular structure of organic matter in landfill leachate.（3）Ceramic membrane aeration was more likely to degrade macromolecular biopolymers and humus,and biodegradable small molecular organic compounds were produced in the components.The B/C value of aged leachate in the first stage increased from 0.1 to 0.39 in 360min,which made the subsequent biochemical reaction possible.However,the B/C value of aged leachate in the second stage showed a trend of increasing at first and then decreasing,and the final biodegradability was 0.21.（4）Under low dosage,the removal rate of COD and TOC in leachate was the highest at the concentration of 40g/m³,which were 13.3%and 33.7%,respectively.the ozone dosage was increased to 20.higher ozone concentration had higher removal rate of organic matter,and ozonation can improve the biodegradability of effluent.Therefore,the ozone concentration of 60g/m³ was suitable from the practical degradation effect and economic point of view.When the initial p H was 6,the removal rates of TOC and COD were the highest,which were 51%and 62%,respectively.However,under alkaline conditions,the biodegradability increased the most.The biodegradability of leachate decreases with the increase of organic matter concentration,and the highest B/C value was 0.62,which greatly improved biodegradability,which was beneficial to the combination with low-cost biological treatment technology.