| Summary: | 碩士 === 國立成功大學 === 環境工程學系 === 106 === This study investigated the lysis of Microcystis aeruginosa cells and degradation of microcystins in the system of titanium dioxide-coated quartz rod under UV light condition. Two major portions are included in this study, materia preparation and selection, and tests of cell lysis and microcystin degradation.
In the first part of this study, material was prepared by coating a titanium dioxide (TiO2) slurry and using dip coating method for preparing a photocatalytic fiber film. The quartz rod used in this study is to overcome the influence of light transmission in water, improving the performance of photooxidation in the system. The experimental results show that the TiO2 film layer coated on the quartz rod dip may remain integral if the coating was below 5 times. When coated with 2 times, the production of hydroxyl radicals reached the highest, at 8.32×10-15 M, among the tested conditions.
The second part of this study is oxidation experiment. The parameters monitored during the experiments include free radical concentration, cell integrity, microcystins concentration, and cell counting. Use oxidant kinetic model to simulate the cell integrity of Microcystis and the microcystins release and degradation. The results showed that in the UV light only system, the cell integrity changed significantly in 8 hours, and then the microcystins was released, and the released microcystins were degraded by about 40% within 24 hours. In UV/TiO2 system, the TiO2 film on the rod reduces the UV transmittance, leading to no impact on cell integrity and no microcystin degardation within 24 hours. Experimental results for microcystin degradation indicte that in the the TiO2/UV and UV only systems, microcystin was degraded by 80% and 70%, repsctively, after 24 hr of reaction. In the mean time, TOC was destructed by 15% for the TiO2/UV. It is shown that hydroxyl radical produced in the system can improve the degradation of the microcystins and degrade the TOC in the water.
To simulate cell lysis and microcystin degradation in the studied systems, the Delayed Chick-Watson Model model was employed. The results show that this model can effectively simulate cell rupture and subsequent degradation of microcystins for the TiO2 film/UV system.
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