| Membrane treatment technology is the main way of advanced treatment of landfill leachate in China.However,the membrane fouling problem in this process increases the operating cost of leachate treatment.In addition,the current popular concentrated liquid recharge treatment method will affect the stable operation of the treatment system.In this paper,a powerful Electrochemical-ozone coupling process was constructed for the purpose of non-membrane advanced treatment,the operating conditions of the process were optimized,the process efficiency and reaction mechanism were explored,and the feasibility of the process were evaluated by combining it with the SBR small biochemical system.The conclusions are as follows;（1）In order to explore the operating conditions of the powerful Electrochemical-ozone coupling process,a single factor experiment was carried out by selecting the current intensity,initial pH,iron powder adsorption density,and ozone dosage.The operating conditions of the coupling process were optimized by the response surface method,and the optimal conditions for the removal of COD and total nitrogen by the process were explored.The results show that when the current intensity is 1.75 A,the initial pH is 6.37,the adsorption density of iron powder is 0.43 g/cm2,and the ozone dosage is 4.42 mg/min,the removal rate of COD is 47.70%,and the removal rate of TN is 82.78%.（2）To evaluate the removal efficiency of pollutants by the powerful Electrochemical-ozone coupling process,the organic pollutant removal characteristics of the coupling process,Electrocatalytic oxidation,Electro-Fenton,and Electro-peroxone oxidation processes were compared under optimal operating conditions using pollutant removal rate,ultraviolet spectrum（UV）,infrared spectroscopy（FT-IR）,and three-dimensional fluorescence spectrum（3DEEM）.The results showed that the coupling process combines the advantages of the Fenton(Fe2+/H2O2)reaction and the peroxone（O3/H2O2）reaction.The COD removal rate was 24.93%,20.21%,and 15.61%higher than that of the Electrocatalytic oxidation,Electro-Fenton,and Electro-peroxone oxidation processes,respectively.It effectively removed large molecular organic pollutants such as fulvic acid and humic acid in secondary effluent,and it had a significant removal effect on aliphatic hydrocarbons,esters,ethers,and phenols,which improved the biodegradability of the secondary effluent from the landfill leachate.（3）To clarify the organic pollutant removal mechanism of the coupling process,the electrocatalytic activity of the electrode was determined using cyclic voltammetry（CV）curves,and the free radicals generated during the reaction were determined using electron paramagnetic resonance spectroscopy（EPR）.The results showed that the coupling process produced various active substances such as·OH and·Cl during the reaction.The contribution of different reactions to organic pollutant removal was obtained through quenching experiments,where the contribution rates of DAO,Fenton,peroxone,and ECO reactions to organic pollutant removal were 66.85%,17.14%,12.36%,and 3.65%,respectively.（4）To investigate the feasibility of coupling the coupling process with a small-scale sequencing batch reactor（SBR）system,the effluent from the coupling process was used as the influent for the SBR biological reactor,and the COD and total nitrogen removal rates were studied.The results showed that at the optimal hydraulic retention time,the SBR reactor achieved a COD removal rate and TN removal rate of 90%and 70%,respectively,which met the requirements of the"Pollution Control Standards for Municipal Solid Waste Landfills"（GB 16889-2008）.（5）To investigate the effect of different electrochemical treatment processes on the microbial community in SBR bioreactors,secondary effluent treated by Electrocatalytic oxidation,Electro-Fenton,Electro-peroxone oxidation,and coupling processes were respectively used as influent for SBR,and the microbial community characteristics of sludge cultured under different electrochemical processes were analyzed by 16S r RNA high-throughput sequencing.The results showed that the microbial community distribution under the coupling process was relatively even and effectively inherited strains in the inoculated sludge.The dominant bacteria in the SBR sludge after coupling process treatment were UBA6140,lactobacillus,and sphingomonas,among which sphingomonas exhibited strong degradation ability towards refractory organic compounds in wastewater.Based on the above studies,the Electrochemical-ozone coupling process effectively reduces the organic matter and total nitrogen in the leachate secondary effluent,and the coupling process is combined with the SBR small-scale biochemical system.The effluent meets the requirements of the Standard for Pollution Control of Domestic Waste Landfill（GB 16889-2008）,and the non-membrane advanced treatment of the secondary effluent of landfill leachate has been realized. |
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