The Process Optimization Research Of Monovalention Ion Exchange Membrane Treatment Concentrated Saltwater

Concentrated seawater is in rich of resources, there will has the mineralizaton and waste of fresh water and at the same time increase the basification of the soil if it be directed emissions, that’s why the development of concentrated seawater is imperative. Electrodialysis enrichment experiment was carried out for underground brine and strong brine after RO treatment, and the mass transfer process of electrodialysis has carried on the simple analysis, the result can be the reference of monovalention ion-exchange membrane electrodialysis used in concentrated saltwater concentration.Study of electrodialysis used in underground brine concentration. The experimental investigation of the main process conditions for the currnet density, the circulation flow of the desalting tank, the type of anolyte with circulation and the concentration of Na2SO4. The results shows that increasing the current density can improve the congcentration rate, increase concentration, improve the choice of monovalent ions, but high current density will increase energy consumption; the circulation flow of the desalting tank has little influence; the type of anolyte with circulation and the concentration of Na2SO4 of chamber solution conductivity has great influence, to replace anolyte with suitable concentration of Na2SO4 solution can achieved of similar effects with raw wates. In the optimal pricess conditions, the currenty densiy of 3A/dm2, anode fluid circulation 5% Na2SO4 solution, the circulation flow of the desalting tank is0.3-0.4 m3/h, NaCl concentration may reach 205g/L, the current efficiency steady at 83%, unit energy consumption of the film to reach 160KWh/t NaCl.Study of electrodialysis used in strong brine after RO treatment. The experimental investigation of the main process conditions for the currnet density, the feed flow of the desalting tank. The results shows that increasing the current density can improve the congcentration rate, increase concentration, but excessive current density will cause concentration polarization which can reduce the concentration effect.With the feed flow of the desalting tank increase, the monovalent ions concentration rate almost unchanged, membrane of monovalent ion selective increase, permeability decrease of bivalent ions, and at the same time the currnet efficiency and energy consumption increase. Under the optimal process conditions NaCl concentration can reach more than 120g/L, the current efficiency steady at 90%, unit energy consumption of the film to reach 177KWh/t NaCl.Under the action of electric migration based on mass transfer occurs, according to the basic equation and electrochemical double membrane theory model of concentrated saltwater in the process of mass transfer is analyzed. Based on the mass transfer coefficient, the total diffusion coefficient, wanter coefficient of electroosmosis, interface layer thickness under different flow velocity, ignoring the influence of the concentration diffusion can be continuous electrodialysis process concentrated solution congcentration of outlet of the room.