Application And Research Of Membrane In Ships' Ballast Water Treatment

The problem of ships' ballast water, which has a long history, is a worldwide problem.International Maritime Organization(IMO) commands each country to equip treatment devicebefore 2009, in order to solve biological pollution problem of ballast water. Nowadaysphysical, chemical, biological methods can not meet the requirement of IMO.Separation process using membranes has been considered as one of the most potentialprocesses because of the superiorities such as the low-energy costing, easily operation, smalloccupy area, simple processes, no pollution, and easily integrating with other technigue et al.So the method of membrane in ships' ballast water treatment becomes the focus in the worldat present. A kind of hollow fiber microfiltration membrane for ballast water treatment hasbeen prepared by using PPESK. The membrane filtration technology has been used toremoval bacteria and microbes for the first time. Ideal results are achieved. It shows thatmembrane treatment has abroad prospects and value in application.First, the microfiltration membrane is prepared. The casting formula is PPESK 16 wt％,DMAc82.33 wt％, DegOH1.67 wt％, in which flux gets to 603.0L·m^-2·h^-1, rejection rate getsto 91.6％. The performance is very excellent.Second, the pollution and cleaning of hollow fiber microfiltration membrane in ballastwater system has been systemically researched. The result shows that the elimination rate ofbacteria from ballast water is 100％. The optimal pressure is 0.1 MPa. The penetrate flux ofmembrane changes a little and gets to stabilization; The pressure of back-washing is 0.03MPa,the time is 20 minutes. The best back-washing liquor is penetrated seawater with 8000ppmNaClO solution, and the highest recovering rate of penetrate flux is 99.61％.The end, according to the requirement of practical condition, application equipment withindustrial module is designed. The penetrated seawater flux is 391.4L·m^-2·h^-1. Thetechnology condition is investigated. The performance of membrane is good after long timeoperation, can also meet the requirement of IMO. Moreover, the industrial module is appliedin the production of deionized water. The result shows that electric conductivity is less than7μs·cm^-1, and water is stable.