| With increasing the national economy, the water pollution becomes more and more serious. Especially, the industrial wastewater has become one of the most important problems in our national environment pollution. People have tried all kinds of methods to treat with the industrial wastewater in a long time. The electrochemical oxidation method is a new advanced treatment method and has attracted a great deal of attention because of its versatility, environmental compatibility and especially, destruction of toxic and non-biodegradable organics by direct or indirect anodic oxidation. The electrochemical oxidation method may treat liquids, gases and solids and does not use any chemical reagents except the electron as the reagent. In resent years, the electrochemical oxidation method have been successfully applied in the purification of domestic sewage, landfill leachate, tannery wastes, oil refinery wastewaters, textile wastes, etc. However there are still a lot of desiderative theory and engineering problems, which should be solved in the application of electrochemical oxidation method. The aim of this thesis is to investigate the electrochemical oxidation degradation of factual industrial wastewater in order to develop the electrochemical engineering problems.The wastewater in a fertilizer plant has a large fluent quantity and the main pollutants are the organic compounds with NH3-N. Although the water quality has met the requirements, the large effluent still made the pollution to environment. The results indicated NH3-N can be removed completely from the fertilizer plant wastewater by using the electrochemical oxidation method. The method does not need to use any medicament and to accommodate pH. This method use Ti/PbO2 as the anode and Ti as the cathode. The removal of NH3-N and the decrease in COD are related to the current density, electrolysis time, pH value, material of anode and cathode, electrode area, mass transfer condition, and so on. The development of the electrochemical cell must be according to the above parameters.A process of combining electrochemical oxidation and ultrafiltration for treating the refining secondary effluent was studied. After the treatment, the quality of the effluent becomes good. COD descends from 37.5mg·L-1 to 14mg·L-1, NH3-N from 47.70mg·L-1 to 1mg·L-1 and muddy from 28.45NTU to 0.53NTU. The chloride ion concentration, current density and flow rate affected the removal of COD and NH3-N in the effluent greatly.To deal with the engineering problems in the treatment of industry wastewater, the characteristics and properties about the filter-press type of the electrochemical cell has been studied for the first time.(1) Effect of configuration on mass transferIt was found that the mass transfer coefficients with mesh electrode are greater than that with the plate electrode. The mass transfer coefficient is related to the inter-electrode gap. When the inter-electrode gap is achieved a certain value (7mm), the mass transfer coefficient is stable. The mass transfer characteristic for the different positions of inlet and outlet is different and dimensionless number groups correlated the equations are obtained by the experiments. The mass transfer shows the best characteristic when the inlet is located on the top and outlet on the bottom of the cell. When the volume of the cell is magnified to eight times the mass transfer characteristics change little. The position of additional nets has the different influences on the mass transfer characteristic. When the nets are located in the exit region the mass transfer characteristic is the highest. The mass transfer characteristic obtained without nets is in the middle. When the nets are located in the entry region the mass transfer characteristic is lowest. The mass transfer characteristic with electrodes at the inlet or outlet is better than that in the middle of cell. (2) HydrokineticsThe residence time distribution in filter-press type of the electrochemical cell with the different inlet-and-outlet systems has been studied to develop a new model to describe the flow characteristic. The pressure drop,Δp measured as a function of mean flow rate within the range of 10-50L·h-1 across the total cell. Two families of curves can be differentiated sinceΔp across the cell for inlet 1 is higher than that for inlet 2. The experimental data can be fitted to the equation. The E(t) curves for every inlet-and-outlet system present conditions of streaking in varying degrees at low velocity in view of the stagnant zone. With increasing the flow rate, the stagnant zone decreases and then disappears. The RTD curves are split into two different peaks, a main peak and a weak peak, which were modeled the combination of the dispersed plug-flow reactor model. The results indicated that the RTD experimental data is in accord with the simulated data very well. R2 is all above 0.98. CFD simulation was also used to study hydrodynamics. Compared RTD models with the pathlines, the flow characteristic in the cell was presented.(3) Dynamics of indirect electrochemical oxidationThe simulated wastewater containing NH3-N in the filter press-type of the electrochemical cell has been studied to review the effect of operative parameter on the removal of NH3-N and then to set up the dynamics equation and mathematics model. The results indicated that the indirect electrochemical oxidation of NH3-N is the main process with a certain concentration of chlorine ion and the direct process can be ignored. The cell performance is influenced significantly with the operating conditions including the current density, flow rate and initial concentration of NH3-N.The process obeys a second order reaction kinetics when the concentration of NH3-N is equivalent to that of electro-generated active chlorine. The information about the spatial distribution of the reactions may be obtained from the Hatta Number. The value of the Hatta Number (<0.3) estimated under different operation conditions implies that most of the reactions of ammonia with active chlorine occur in the bulk solution. It provided the effective information to design the electrochemical cell.Based on the reaction mechanism of active"Cl", the mathematical model was presented by the application of Equation, Faraday Law and the determination of mass transport coefficients. The model describes the linear relationship about concentration-. It is suitable in the practice of the mathematical model. The average error is Materials Balance electrolytic time4.62%, which was mainly obtained from the characteristic of indirect electrochemical oxidation...
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