The Study On Disinfection System Of Ballast Water With UV/O₃

Ballast water is taken aboard in most vessels in order to provide trim and stability within operational and engineering safety standards. And the daily global transport of organisms in ballast water is suggested to be in excess of 10,000 species per day making this a very important vector for the dispersal of marine organisms and environmental deterioratation. About at least 500 organisms-invaders have been documented having been transported by ballast water. In response, various measures and national regulations have been promulgated to reduce or prevent future introductions in USA, Australia, and Newzealand. The International Maritime Organization (IMO) established a draft convention -the Control and Management of Ships-which has been carried out since Feb. 2005.This thesis made the study on treatment of ballast water with UV/O₃ process.A stainless steel filtration and a double lamp-house photochemistry reactor were designed which structure is simple and of high efficiency of ray radiation and solution of ozonation. The reactor offers a new design for treatment of ballast water. In bench scale test, outflow of SBR reactor was used as experiment water. We made researched on the three different process(UV, O₃, UV/O₃) and found that excelleces of processes in file: UV/O₃>UV>O₃. Under the condition: Hearous GPH436T5VH UV lamp, flow of oxygen 0.06 m3/h, the bacteria survival percentage was less than 7% within 7s and 3%within 20s, the survival ratio of E .coli was more than 99%.In pilot scale test, system water with natural assemblages of organisms was pumped from harbor in Weihai. E. coli, total bacteria, and chlorophyll-a survival rations were investigated by UV, O₃, UV/O₃ processes under various experimental conditions. The results of excelleces of processes in file: UV/O₃>UV>O₃ all the same. UV/O₃ was very successful in killing the bacteria, the survival percentage only 0.5% if flow of oxygen in excess of 1.9g/h and hydraulic residual time 6s. Results also indicted that UV/O₃ process was efficient to remove protozoan and algae from the water.