Treatment Of Ballast Water Using Ultrasound-sulfate Radical Technology

Ballast water is a major factor contributing to introductions of aquatic plants and invasive macroinvertebrates.Although it is taken aboard in most vessels in order to provide trim and stability within operational and engineering safety standars.Ballast water has brought a huge loss to every coastal country at present.The GEF has confirmed that ballast water to be one of four great threats to the oceans.2004,IMO passed the International Convention for the Control and Management of Ships' Ballast Water &Sediments.This contains determined appropriate standards of ballast water treatment.Be based on the results of the other members in ballast-group,the ultrasound -sulfate radical technology has been proposed and studied to treat ballast water.The paper used ultrasound technology to treat the unicellular algae in ballast water at first,such as P.subcorodiformis,Dicrateria sp and Chlorella vulgaris.After search for the best combination of power and frequency of ultrasound,combined with the sulfate radical technology,the lethal effect,physical harm and the content of chlorophyll of unicellular alga were investigated,and the concentration of anions in water before and after treatment was analyzed.The conclusions are as follows:(1) When using the ultrasound technology to treat the three species of algae with the power of 500W,the treating time of 5 min,and the frequency of 50%,the results showed that P.subcorodiformis and Dicrateria sp were all die,the largest lethal rate of Chlorella vulgaris was 76%.(2) The three species of algae were all dead by using the ultrasound -sulfate radical technology.With the concentration increasing,the treating time of ultrasound was significant decreasing.As the power of ultrasound was 500W,the treating time was 1 min,and the frequeey was 50%,the concentration of sulfate radical was 5.35g/L,the lethal rate s of the three algae were 100%.(3) The increacing of chlorophyll a was retrained after the treating of ultrasound -sulfate radical technology.Under the same environment,the regression rate of the same algae was rising with the increasing of concentration of sulfate radical.(4) To assay the water quality which was treated by using the method of ultrasound -sulfate radical technology,the results showed that the Cl~- were not changed between treated and untreated.,the concentration of sulfate radical was increasing,other Cl~- were not appeared,the concentration was smaller under the assaying which was secure emission.(5) The treating effects which the ultrasound was used firstly,and the sulfate radical was used secondly was better than which the sulfate radical was used firstly,and the ultrasound was used secondly,when using the combine of ultrasound -sulfate radical technology.