Study Of Desalting High Strength Brine Using Vacuum Membrane Distillation Process

Membrane distillation (MD),which use hydrophobic microporous membrane asbackstops ,is an innovative membrane separation technique , it possess excellences that elsemembrane processes lack , accordingly , it is helpful that MD become a low-cost and efficientseparation technique .In this paper, the feasibility and superiority of treatment of differencecomponents by VMD were studied. Some factors, such as the temperature of feed , the flowrate of the feed, the vacuum degree of cold side as well as the concentration of feed, wereobserved. Two kinds of commercial membranes PVDF(Microporous poly vinylidene fluoride)and PP (polypropylene) have been used. Results are as following:1. With increase of the vacuum degree of the cold side ,the flux been boosted .When thetemperature of feed increased, the flux increased sharply. The flux was enhanced with theincrease of the flow rate of feed. When the concentration of feed increased, the flux decreased.2. It was introduced that PP hollow fiber porous membrane and its application onBrackish water desalination by vacuum membrane distillation, production specificconductance was about 4μs.cm-1,reject rate reach 99%; membranes do nothing butbackstops , its don't distinguish chemistry component .3. The optimum conditions are as follows : the temperature of feed is 65℃; the vacuumdegree of the cold side is 0.085Mpa ; the concentration of feed is 20g/L; the temperature of thefeed and the vacuum degree of the cold side had great influence on the membrane fluxes inVMD process, the concentration of feed is lesser factor .4. After period of time , membranes were contaminated .Using different formulas cleanthe membranes which had been contaminated ,experiment testify that cleaning effect wasoptimization when using 0.5mol/L hydrochloric acid and 0.05mol/LEDTA .5. It was introduced that the polypropylene (PP) hollow fiber porous membrane ofdifferent gauge pore sizes and its application on disposing bitter and salty water by vacuummembrane distillation , production specific conductance was about 10μs.cm-1,reject ratereach 99%; experimental results showed that the flux increased ,with the augment of pore sizeof membrane ,but production specific conductance hold the line .6. design practicality applied equipment of VMD , simply making economy budget .