Simulation Analysis And Optimization Of Water Treatment Process Based On Magnetic Characteristic

Membrane fouling is caused by complex physical and chemical interactions between various contaminated components in the feed and between these components and the membrane surface.Membrane fouling will reduce the performance of ultrafiltration membrane and increase the filtration cost.In this paper,magnetization,a green and convenient method,is used to alleviate inorganic pollution during ultrafiltration.In the experiment,COMSOL Multiphysics was used to study the influence of magnetic field on the velocity of water phase and the deposition of inorganic particles during filtration.In the process of simulation,the software is used to build a model that conforms to the real device size,and the operating conditions are set according to the actual operating conditions.In addition,porous media model is used to simulate ultrafiltration process,instead of non-slip wall.Firstly,by using COMSOL numerical simulation,three physical fields,magnetic field,flow field and porous media,are coupled to study the change of fouling layer on membrane surface during filtration.It is assumed that inorganic pollution particles form a very thin dirt layer on the membrane surface during filtration.With the process,the volume fraction of inorganic particles on the membrane surface is used to show the pollution of the membrane surface.According to the results of simulation calculation,the velocity distribution and change of water in the device during filtration are displayed by using the nephogram and line chart of software post-processing,at the same time,due to the influence of water flow movement on the volume fraction distribution of inorganic particles,the difference between the applied magnetic field and the control group is compared,and the action rule of the magnetic field is summarized.COMSOL simulation results show that the velocity of water flow in the device will be increased by external magnetic field,resulting in the decrease of the volume fraction of inorganic pollutant particles deposited on the membrane surface.It can be concluded that due to the increase of shear stress,the deposition process of fouling particles on the membrane surface slows down.Under the action of magnetic field,the increase of fluid velocity in the filtering device will bring more inorganic pollutant particles to the reflux outlet instead of depositing on the membrane surface.Next,the simulation results obtained by COMSOL are verified by the laboratory-scale experiment of diatomite solution filtered by ultrafiltration membrane.Single-cycle experiment and opposite-cycle experiment were conducted respectively.The specific flux（J/J₀）and water quality indexes(turbidity,conductivity,Si O₃^2-concentration and Ca²⁺concentration)of the membrane under two different operating conditions（with or without magnetic field）were compared,and the influence of magnetic field on inorganic pollution and membrane performance was studied.Through experiments,it was found that the membrane specific flux gradually increased and then gradually decreased to a stable level during the filtration period.The specific flux of the membrane under magnetic field is higher than that of the control group.The magnetic field acting on the membrane filtration process can increase the filtration flux and improve the membrane performance to a certain extent.Whether it is turbidity,conductivity,Ca²⁺concentration or Si O₃^2-concentration,the value of reflux water is higher than that of effluent water under two operating conditions.The values of effluent indexes are all smaller than the original solution,the values of reflux water indexes are all larger than the original solution,and the values of reflux water indexes under the action of magnetic field are all larger than those of the control group,which indicates that the increase of fluid velocity in the magnetic field reactor will bring more polluted particles to the outlet.The index values of effluent under the action of magnetic field are all less than those of the control group,indicating that the magnetic field will slow down the pollution degree of effluent.The conclusion is consistent with the conclusion that the magnetic field has a certain effect on alleviating membrane fouling in the experimental and simulation results.