Research About Application Of Electroflocculation Technology In Reverse Osmosis Concentrated Water Reuse

With the rapid development of industries,the discharge of industrial wastewater has increased rapidly,especially the reverse osmosis concentrated water discharged by coal chemical industry,which has made the global water pollution more serious.Therefore,reuse of reverse osmosis concentrated water is an inevitable trend and requirement for the development of coal chemical industry.Reverse osmosis concentrated water has two characteristics:high salt content and high fouling substance content.Before reuse,the reverse osmosis concentrated water must be pretreated.The pretreatment of reverse osmosis concentrated water is the key and difficult point of reuse.In this thesis,self-designed electroflocculation small scale test device,the effect of current density,electrolysis time,pH value of raw water,temperature of raw water and magnesium chloride on the total silicon removal rate in reverse osmosis concentrated water was studied by using single factor analysis method.The results showed that under the conditions of current density 10mA/cm2,electrolysis time 10min,pH value 11 and magnesium chloride 800mg/L,the removal rate of total silicon was as high as 90%,which was controlled below 20mg/L.CFD technology and Fluent software were used to simulate the flow field structure of the electroflocculation reactor and analyze the hydraulic characteristics such as velocity and turbulence intensity in the reactor.By optimizing the reactor,it can achieve better turbulent mixing of fluid in the electroflocculation reactor,reduce mass transfer resistance,reduce polarization,improve current efficiency,shorten electrolysis time and reduce energy consumption.The research results show that the changing plate length,plate spacing,increase the feed rate can significantly increase the turbulent kinetic energy.By using square column disturbed flow tube is the best way to improve the flow pattern,can reduce 44.8%of the reactor volume,and can improve the turbulent kinetic energy of 20 times,to strengthen the effect of mass transfer.Determine the final plate structure:plate length is 1.5 m,the water flow velocity of 0.01 m/s,plate spacing is 4 cm,disturbed flow tube 1 cm length,interval of 10 cm Settings.According to the results of the pilot test and the optimization results of the electroflocculation reactor,the electroflocculation reactor was processed and the pilot experiment was conducted on site.The experimental results show the removal rate of total silicon treated with reverse osmosis concentrated water by electroflocculation technology is 81.4%,for the removal rate of calcium hardness is 61.6%,for the removal rate of magnesium hardness is 83.7%,the turbidity is stable below 30 NTU.The reduction of hardness,total silicon and turbidity greatly reduces the scaling and fouling of the reverse osmosis membrane.