| Object:With the rapid development of society and the economy,the discharge of industrial wastewater brings great pollution to the environment,and dye wastewater as a kind of industrial wastewater,it is difficult to achieve the balance between the treatment effect and the cost.As an electrochemical method,electrocoagulation technology can treat various kinds of wastewater efficiently.However,problems such as high energy consumption,passivation of electrodes,and the need to add electrolytes to increase conductivity have become obstacles to the development of electrocoagulation technology.This thesis combines electrocoagulation technology and air-lift reactor to construct a new electrochemical-gas-lift reactor,which can provide some reference for the design and application of water treatment reactor in the future.Methods:In this study,an Euler-Euler gas-liquid two-phase model was used to numerically simulate the flow field of the reactor using the computational fluid dynamics（CFD）method.The effect of structural parameters（ratio of rising and decreasing regions area,top gap height,bottom gap height,etc.）on the internal gas-liquid flow state was investigated using liquid phase velocity and gas content as parameter indicators.Based on the numerical simulation results,an experimental-scale electrochemical-airlift reactor was constructed and applied to treat simulated dye wastewater.Using reactive black 5 dye（RB5）as the target pollutant,single-factor tests were carried out to investigate the effects of electrode type,current density,p H,aeration rate,electrolyte type and concentration,and initial RB5 concentration on the treatment effect.Finally,based on the single-factor test,the screened influencing factors were optimized using the response surface methodology to obtain the optimal operating parameters for treating RB5 dye wastewater.Under the optimal treatment conditions,three representative dyes,Congo red,Methylene blue and Neutral orange,were treated with simulated dye wastewater prepared from actual wastewater treatment plant.Results:The optimum structural parameters of the reactor in this thesis were obtained by simulation:the area ratio of the rising and falling areas was 1:2.3,the top gap height was 4 cm,and the bottom gap height was 2cm.The influencing factors and parameters for the removal of RB5 dye wastewater were determined,among which the most significant influencing factors were:current density,electrode spacing,and aeration rate.The optimum operating parameters were obtained by response surface model analysis:current density 2.0m A·cm-1,electrode spacing 2.0 cm,and aeration rate of 350 m L·min-1.Finally,the removal rates of three representative dyes at 100 mg·L-1 concentration were 87.64%,81.25%and 72.37%,respectively,all above70%.Conclusion:The electrochemical-airlift reactor developed in this study has a good treatment effect on dye wastewater and is feasible for practical application. |
