ABSTRACT
A Study on Blue-green Algae Treatment by
Ozone Microbubble in Stagnated Water Area
Si-On Go
Department of Health Enyironment,
The Gradute School
Hoseo University
Seoul, Korea(Supervised by professor Sang-Houck Lee)

Because of occurrence large quantities of algae(especially Cyanobacteria) and cause serious water pollution, it is difficult to use water, especially in summer, reservoirs built to secure water resources, multi-purpose dams and stagnated water areas made by 4 Rivers Development Project.
As an alternatives for these problems, various ways are used such as forced water circulation, bottom oxygen supply, algicides spray and separate disposal, but the effect of control algae generation and economical efficiency are relatively poor and may cause secondary pollution by algicides.
The effectiveness of mitigation measures to reduce green algae are quite low and not easy to select appropriate method.Because of the lack of solutions about these essential problems, it is inevitable to take control algaes directly in the field.
Ozone microbubbles are erupting inside of water, so the residence time is long and solubility is increasing as an extension of surface area. Also dispersion force and penetration are strong and able to get algicidal effect by OH* radical generated crushing effects when it disappears.
Dispersibility and penetration effects of ozone microbubbles are fine and showing high effectiveness. Moreover, these microbubbles turns to oxygen after separated and supply oxygen to aquatic ecosystem.
Ozone microbubbles are effective in removal and restraint odor caused by occurrence of algae and anaerobic reaction, reduction of turbidity, improvement of water quality and preventing nutrients elution by resolvement anaerobic condition of bottom materials, and ultimately contribute to the aquatic ecosystem.
The results of preliminary test and field examination are as follow,
- By microscopic analysis in the laboratory, the ozon injection rate of Algae''s movement stops for shock is 2ppm.
- By the field examination, deteriorated water quality in the stagnated water area had been recovered 20days after starting operation, and there`s no more growing of algae in high density. 240g per day of ozon injection is enough to maintain water quality.
- If Chloropyll-a is ozonated, the color of algae turns from green to light brown. This means that the original color of chlorophyl is decolored by ozone and concentration of ozone injection against of algae water layer was about 6~8㎎/L.