The Study On Efficient Sterilization System Of Ships’ Ballast Water Treatment

Ballast water is important measure to guarantee secure voyage of ships, but it can notavoid taking along a large number of aquatic organisms in the process of injection anddischarge. When these aquatic organisms invade to the local environment with ballastwater, they will cause serious influence on Marine ecological system, human health andeconomic development of the port city. The global environment fund has confirmed thatthe damage of marine environment caused by ships’ ballast water is one of the four kindsof Marine threats. For this reason, in2004,The international maritime organization inLondon passed the《International Convention for the Control and Management of Ships’Ballast Water and Sediments》.It sets a ballast water discharge standard, and it demands thatthe ballast water discharged by ships from different countries must be disposed and meetthe correlative requirements before2016.Contraposing the serious situation, this paper puts forward a treatment technologyroute that combined filter with ultraviolet radiation sterilization to treat ballast water. Filter,as the first primary treatment, can wipe off solid particles and organisms whose sizes aregreater than50μm in the ballast water. Ultraviolet sterilization, as the second treatment,can kill the organisms less than50μm. This article, based on the theoretical research anddesign research, aims to devise a set of effective ship ballast water processing system whichcan be used on the ships. Specific research content and conclusions contain the followingaspects:1. On the basis of many related literatures, this article sum up the environmentalproblem caused by ships’ ballast water; stated the phenomenon that the harmful biologicalcarried by ships’ ballast water seriously dangerous to marine environment; illustrated theimportance of ballast water treatment. And it introduced the content of the convention ofballast water, including its making and implement progress.2. This article researched the basic sterilization theory of ultraviolet rays, and stated itsfeasibility for the technology of ultraviolet rays to deal with ballast water from two aspectsof theory and practical application.3. Beginning with the distribution of dose of ultraviolet rays in the reactor cavity, thisarticle finished the design and modeling of the efficient sterilizer with capacity of300cubic meters per hour. In the sterilizer, the dose of ultraviolet rays can reach to100000μJ/cm2. It also made some analysis of flow field of the sterilizer, pointed out some shortages of the model on the structure, and then pointed out the method to improve thisdevice.4. Put forward several design methods of special filtration components in detail. On thebasis of the design of filter screen, the design of cylinder, the design of sealing and thedesign of driving medium, it finished design and modeling of self-cleaning suction filter.Summarized the computing method of mesh pressure and filter cake drop. By calculationthe mesh pressure drop of0.012MPa, the total pressure drop of0.047MPa. Both are accordwith experience criteria.5. Based on the sufficient study, this article designed the treatment process of ballastwater, built300m3/h ships’ ballast water treatment system, and completed the design ofthe control system.