| Summary: | 碩士 === 弘光科技大學 === 環境工程研究所 === 99 === The algae grow and reproduce in lake and reservoir easily, which has serious influence upon normal operation of treatment plant and effluent quality in waterworks .In this study, pre-ozoneion and coagulation processes are used to study organic matter changes in eutrophic raw water. For the raw waters containing algae, the impact of pre-ozoneion process before coagulation on organic matter removal and byproduct precursors disinfection are also studied. To assess the advantages and disadvantages of the oxidation or disinfection process during water treatment, the raw water take from reservoir, and pure algae culture Microcystis aeruginosa which incubation in laboratory are conducted. To estimate the effect of pre-ozone process on organic removal during coagulation procedure. The disinfection byproducts precursors (DBPs) are analyzed, including trihalomethanes (THM) and haloacetic acids (HAA). The results showed that after pre-ozone (O3 dose = 1.0 mg/L) treatment for the eutrophic reservoir water, the non-purgeable dissolved organiccarbon, (NPDOC), trihalomethane formation potential (THMFP), and haloacetic acids formation potential (HAAFP) were tended to increase, especially HAAFP. It mainly due to the algae existed in the original water would destroy by ozone and release extracellular polymeric substances (EPS) and intracellular material (IPS), which have the possibility to produce DBPs. As for laboratory-cultured Microcystis aeruginosa, it showed markly increase formation of NPDOC and DBPs. Particularly, THMFP and HAAFP increased by 1.5 and 3 times, respectively, when there is bromide(Br-= 0.5 mg/L) in the water under the same conditions. In addition, pre-ozone prior the coagulation treatment can remove some of NPDOC, but the removal of THMFP and HAAFP is not obvious. It is significantly lower compared to the direct coagulation of raw water. It shows that the organic matter with potential of DBPs formation released by the ozone oxidation of raw water eutrophication algae can not easily be removed of the follow-up coagulation process. Therefore, pre-ozone process combined with the coagulation treatment have negative effect to the removal of organic matter. Mainly due to ozone can damage algae and release of dissolved organics from algae organism which are THM and HAA precursors. The DOC released in the ozonation process, the follow-up coagulation process can not effectively remove them. On the other hand, eutrophic raw water under Br-containing conditions, the THMFP and HAAFP will be reduced after pre-ozone treatment. The suggest is that ozone oxidized organic matter or algae metabolites (EPS and IPS) transferred to THM of HAA precursors.
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