Study On Characteristics Of Advanced Treatment Of Landfill Leachate By Electric Flocculation-ozone Air Flotation

In view of the high content of refractory organic matter in secondary effluent of the main leachate treatment process of"pretreatment+secondary biological treatment+membrane advanced treatment",which leads to the problems of heavy load of direct membrane advanced treatment,serious membrane pollution during long-term operation and low water production rate,the electric flocculation-ozone air flotation advanced treatment process is established.Explored its treatment characteristics and process operation mechanism of leachate secondary effluent,and used it in conjunction with the membrane treatment system（reverse osmosis,RO）,analyzed the influence of the introduction of the process on the membrane treatment system,and the main conclusions are as follows:（1）In order to explore the characteristics of leachate secondary effluent treatment by electrocoagulation-ozone air flotation process,the ozone dosage was 2.98,6.22,12.22and 20.34 mg/min,the current density was 0,5,10,15 and 20 m A/cm²,and the cathode was SS,Al and C-PTFE,respectively.The removal effect of organic matter from leachate secondary effluent by electric flocculation-ozone air flotation process was investigated.The results showed that when the ozone dosage was 12.22 mg/min,the current density was 20 m A/cm² and the cathode was C-PTFE,the removal effect of pollutants was the best,and it had a significant removal effect on COD,chroma and humic acids.（2）To clear the electric flocculation and ozone air flotation technology in the operation of the mechanism of contrast under the condition of different control production of reactive oxygen species component,it was concluded that the best properties under the condition of leachate secondary water treatment,electric flocculation and ozone air flotation process to generate the most content of H₂O₂ and·OH,showed that this system under the condition of CLP flocculation and ozone oxidation mechanism of promoting efficiency strongest.According to the quenching experiment,·OH,H₂O₂ and·O₂^-played a major role in the removal of organic compounds in this process,in which·OH’s contribution rate was up to 95.16%.The results of the investigation on the process mechanism showed that·OH can be generated by the oxidation of O₃ and O₂,and H₂O₂generated by the reduction reaction of O₃ and O₂ at the cathode was another way to effectively promote the generation of a large amount of·OH in the system.In addition,the special multi-aperture structure of C-PTFE cathode surface can increase the generation of active sites on the cathode surface,catalyze the decomposition reaction of O₃,significantly increase the content of·OH in the system,and improve the removal of organic matter by electric flocculation-ozone air flotation process.（3）In order to explore the influence of the introduction of electrocoagulation-ozone air flotation process on the membrane treatment system,RO effluent properties and RO membrane fouling properties were analyzed under the optimal operating conditions.The results showed that the COD,conductivity,turbidity,chroma and ammonia nitrogen of RO clean water were reduced by 75.66%,15.04%,96.56%,61.22%and 70%,respectively,and the desalting rate was increased by 41.07%after electrocoagulation-ozone air flotation process.The reduction rates of RO concentrated water yield,COD,conductivity,turbidity,chroma and ammonia nitrogen were 25%,11.80%,29.67%,72.22%,56.21%and 56.21%,respectively.And RO water rich in acid,aromatic protein degradation and humic acid type of organic matter was significant,that electricity flocculation-ozone gas float process anode Al form Al department coagulants promotes the solid particles in the flocculation precipitation,O₃ can effectively oxidation for small molecule organic macromolecular organic matter,system generated in the·OH can oxidation of organic part of the functional groups,Thus the organic load of RO membrane treatment process can be effectively reduced.The study on the pollution performance of RO membrane showed that the electroflocculation-ozone air flotation process can effectively increase the specific flux of RO membrane,reduce the deposition of pollutants on the surface of RO membrane,which was conducive to the alleviation of RO membrane pollution.Based on the above research,the advanced treatment of leachate secondary effluent by electrocoagulation-ozone air flotation process can reduce the pollution load and concentration yield of reverse osmosis system,effectively relieve the membrane pollution,and provide a new technical idea for leachate treatment.