| Summary: | 碩士 === 淡江大學 === 水資源及環境工程學系碩士班 === 94 === Several papers had pointed out zero valent iron could degrade atrazine effectively. However, different operation conditions applied among these studies make the results quite different. In this study, Zero-valent iron (ZVI) for degradation of atrazine was applied in different treatment process and the results were compared. Three treatment systems were studied, including (1) zero valent iron column bed reactor, (2) fluidized zero valent iron reactor, and (3) zero valent iron purging bed reactor. All of them have their inherited advantages and disadvantages which will be elucidated along with the suggestions of best operational conditions for these processes.
Both reductive and oxidative mechanisms are responsible for degradation of atrazine on our experiment. In the fluidized zero valent iron reactor and zero valent iron purging bed reactor, the degradation of atrazine by reductive mechanism is a much slower process than that by oxidative mechanism, and is pH dependent. At pHs of 3 and 2, atrazine degradation efficiency increased with increasing ZVI dosages, up to 70% and 90%. But the increasing trend is not observed for system controlled at pH 4.0. It is due to passive surface coating by corrosion iron products at this pH. The concentration of hydrogen at pH 4 is not enough to reduce the amount of iron corrosion products, which influence transfer of electrons and reduce the effectiveness of atrazine degradation. Therefore, operational pH of under 3 is suggested. But the effect of pH is not the same with that observed in column bed reactor. The effectiveness of atrazine degradation is better when influent pH is controlled at near neutral. When influent pH was controlled at acidic range, more iron corrosion products were produced, decreasing the effectiveness of atrazine degradation. Addition of H2O2 greatly enhanced removal of atrazine through Fenton reaction, and atrazine degradation was completely within the first few minutes of reaction.
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