| The output of municipal solid waste was increasing with the development of economy and city quickly, and the production of landfill leachate was also increasing. How to treat landfill leachate appropriately always was a difficult problem which needed to be solved. The three-segment treatment process “pretreatment + biochemical treatment + advanced treatment” was usually adopted. The effluent of biochemical treatment still had some nitrogen and COD etc. Nowadays membrane technology was usually adopted as advanced treatment, which made sure the effluent of landfill leachate reach the standard. But there were some problems such as high prophase investment 、 high running expense and that concentrated solution was difficult to treat. After the new revising <Standard for pollution control on the landfill site of municipal solid waste> had been publishing, developing other advanced treatments for landfill leachate which had engineering value was imperative.The study on the influence of different electrode materials for the treatment effect of combination process showed that RIS had better treatment effect of ammonia nitrogen and COD than ITS and BDD. The treatment effect of TN from RIS、ITS and BDD didn’t have obviously different. Compared with RIS and ITS, BDD anode would lead to produce a large number of inorganic disinfectant by-products. Because the low price of RIS was beneficial to expand of the experiment scale, the study selected RIS as experiment electrode. From the contrast experiment of cathode materials, graphite felt and Cu90Ni10 had no obvious influence on the treatment effect of pollutants. Because of the low price of graphite felt, the study selected graphite felt as experiment electrode.the study on the influence of different electrode materials for the treatment effect of combination process by selecting five kinds of electrode materials as candidate. Selecting the RIS of demensionally stable anode as anode and graphite felt as cathode.Single factor experiment was about the effect factors of combination process which including plate distance、velocity、p H and Cl- concentration.the result showed that plate distance、velocity and Cl- concentration were selected as optimization conditions.The study on optimization of combination process by response surface methodology resulted:the optimum conditions for COD removal were 3.8cm plate distance, 1m L/min velocity and 5556 mg/L Cl- concentration. And the optimum conditions for TN removal were plate distance 5.7cm, circulation velocity 1m L/min and Cl- concentration 5437 mg/L. The optimum conditions for TP removal were plate distance 3.02 cm, circulation velocity 6.26 m L/min and Cl- concentration 3000 mg/L.On the optimum conditions, the study found that the experimental value of COD removal efficiency was 84.6%(forecast value was 85.4%) and the experimental value of TN and TP removal efficiency were 86.4% and 82.11% respectively(forecast value 93.0% and 79.54%). The quadratic response sur face model with significant level was obtained by simulation and analysis of variance.Exploring reaction mechanism of combination process preliminarily by researching water quality of influent and effluent、composition of precipitate of contrast experiment. The results included: removal of nitrogen of landfill leachate was due to evolution of chlorine of RIS anode, which was electro-oxidation; the removal of COD、color and TP were due to the adsorption sedimentation of floccule or flotation. The advanced treatment of organic compounds and nitrogen phosphorus with electrochemical combination process was combined with electro-oxidation、flocculation and flotation and mutual promotion.Electrochemical combination process could be used to advanced treatment of organic compounds and nitrogen phosphorus, and the effluent quality could reach the standard. The study has high reliable practical value, providing theoretical basis and date support for further research. |
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