Study On Coupling Technology Of Water Treatment Based On Electrocoagulation And Advanced Oxidation Technology

In recent years,electrocoagulation technology has developed rapidly due to its simple structure,easy operation,and in-situ flocculation.Its main working principle is to adsorb pollutants through in-situ flocs.Especially in the field of heavy metal ion wastewater treatment,electrocoagulation reflects its high-efficiency and rapid treatment characteristics.However,the components in modern industrial wastewater are becoming more and more complex,and the proportion of organic matter is increasing.The single electrocoagulation system cannot achieve an effective treatment effect.This thesis proposed and verified a mechanism of electrocoagulation-advanced oxidation process coupling system to treat wastewater.Firstly,the in-situ generated hydroxyl radicals were used to break the long carbon chain and complex group structure of organic matter,and then the in-situ generated flocs were used to desorb organic matter with small molecular structure in turn improve the treatment effect.The coupling system can in situ generate hydroxyl radicals and adsorb flocs simultaneously.In this thesis,7-hydroxycoumarin was used as a fluorescence detector to calibrate the production of hydroxyl radicals,and the decontamination mechanism under this system was studied by adjusting the process parameters.The research of this subject is of great significance for solving the problem of low efficiency of electrocoagulation technology in the treatment of organic wastewater.The first part of this thesis used a titanium-plated tin oxide(DSA)catalytic anode,graphite cathode and iron particles as particle-filled electrodes to construct a three-dimensional electrolytic coupling system to simultaneously generate hydroxyl radicals and adsorb flocs in situ.Under the same charge,the yield of hydroxyl radical in coupling system can reach 56.38% of that of the single electrooxidation system,and the yield of flocs can reach 83.56% of that of the single electrocoagulation system.Under the same charge,different aeration conditions will affect the performance ratio of the coupled system and the single electrocoagulation system,and also affect the structure of the flocs.The application of titanium-plated tin oxide(DSA)catalytic anode will increase the redox potential of the entire coupling system and affect the structural transformation of iron flocs.The method of coupling electrocoagulation and electro-catalytic oxidation technology by constructing a three-dimensional electrolysis system is feasible,but the energy consumption of the system is relatively large,and part of the electrical energy is consumed by the side reaction of oxygen evolution at the catalytic anode,which also lead to the problem of low hydroxyl radical yield at the same time.Therefore,the second part of this thesis constituted a coupling system of electrocoagulation and electro-Fenton technology by adding an air breathing cathode part to the electrocoagulation structure,and this method can achieve the purpose of simultaneously generating hydroxyl radicals in situ and adsorbing flocs in situ and improve effective current efficiency.The initial reaction p H controls the electrochemical reaction type of the iron anode,and the initial p H affects the removal mechanism of coumarin(COU)in the coupling system.Under the acidic condition of the initial p H=2-3,the electro-Fenton reaction in the coupling system plays a leading role;when the initial p H=3-4,the COU removal mechanism in the coupling system is synergistically effected by the electro-Fenton reaction and the electrocoagulation reaction;when the initial p H=4-6,the COU removal mechanism in the coupled system is controlled by the electrocoagulation reaction.Dissolved oxygen(DO)value is not only one of the important factors that affect the reaction rate of electro-Fenton,but also can control the structure of the flocs.The flocs produced under different aeration conditions are different,and the removal mechanism of coumarin in the coupling system is also different.In order to study the performance of the two coupling systems,this thesis optimized the reaction current density,particle electrode filling amount,aeration type and other parameters to achieve the best processing performance.The above-mentioned research and analysis demonstrated the feasibility of electrocoagulation coupled with advanced oxidation technology,and confirmed the possibility of simultaneous generation of hydroxyl radicals and adsorbed flocs in situ.