碩士 / 國立中興大學 / 環境工程學系所 / 100 / In recent decades, eutrophication of water reservoirs and lakes has drawn much attention. Currently, there are 21 major water reservoirs on Taiwan''s main island, and 34 on its isolated islands. Most of these water reservoirs on main island have been identified as eutrophic and 30 to 33 out the 34 on isolated island have been identified as eutrophic. In China, the most seriously eutrophic lakes are at the downstream of Yangtze River and at the southwestern provinces. The Great Lakes at USA are also threatened by eutrophication. Coming along with eutrophication, the proliferation of algae, especially toxin-generating Microcystis aeruginosa, poses safety concerns in drinking water supply. Water treatment plant usually use chlorination to tackle this problem by breaking the algal cells. However, the released algal toxin cannot be easily removed by coagulation or flocculation. In the meantime, this measure may also generate disinfection byproducts, such as trihalogenated carbon. This study is aimed to develop a technology for effective inhibition of Microcystis aeruginosa and removal of released microcystin LR, the most toxic form of all toxins generated by Microcystis aeruginosa.
The material used in growth inhibition test is nanosilicate platelet (NSP) derived from natural clay minerals. At as low as 10 ppm, NSP demonstrated strong growth inhibition effect. The effects seem to be direct proportional to the dosage. However, similar dosage on two other bacteria, one Gram positive and one Gram negative, showed very different results implying that the growth inhibition effect of NSP could be selective. Two sets of turbidity tests were carried out and traditional coagulant, trivalent aluminum and trivalent iron showed much better results than NSP. However, the results clearly support that NSP is still a good candidate at high turbidity since aluminum and iron are not favored to be added into the water reservoirs directly due to health hazards and taste problems. A toxin adsorption test has been conducted to see if NSP can effectively remove microcystin-LR. The results showed that at 100-ppm and 500-ppm dosages, the removal is 47% and 99%, respectively, suggesting NSP can serve as a very good adsorbent for microcystins.
| Identifer | oai:union.ndltd.org:TW/100NCHU5087009 |
| Date | January 2012 |
| Creators | Cheng-Hao Li, 李承澔 |
| Contributors | 張書奇 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 102 |
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