| Summary: | 碩士 === 臺灣大學 === 環境衛生研究所 === 95 === Chlorination is a common disinfection process in Taiwan with the advantages of efficient microorganism control, low cost and fast. However, it also generates toxic disinfection by-products because of the reaction between organic matter and chlorine. The best way to reduce the formation of THM is removing the organic precursors, and advanced oxidation processes has been shown to be effective to remove the organic precursors. The objective of this study is to evaluate the effects of UV/H2O2 process on DBPs precursors’ removal.
Four organic precursors were selected in this study to evaluate the effect of different structures and functional groups on THM formation. The variation of THM formation and changes on precursors’ functional groups by UV/H2O2 process was also evaluated.
At lower chlorine doses (10 and 20 mg/L), the total THM formation decrease with increasing DOC concentrations and no Br-THM species was observed when resorcinol and phloroglucinol were tested. When higher chlorine dosage (100 mg/L) is applied, Br-THM species is obtained and the total THM formation increased dramatically. It is inferred that resorcinol and phloroglucinol have higher steric hindrance which block the reaction of bromine, and higher chlorine dosage provides oxidative force to change the structure of resorcinol and phloroglucinol and thus promote Br-THM and higher THM formation.
When the organic precursors were treated with UV/H2O2 process, the THMFP of three aromatic precursors decreased with photolysis time. However, the highest THMFP for aliphatic 1,7-heptanediol was observed after 10 minutes of UV photolysis. The FTIR spectrum revealed that peaks of hydroxyl, hydrocarbon and carboxylic structures were observed after UV photolysis. This provided some information to demonstrate the change of the functional groups during the photolysis and the oxidation efficacy of UV/H2O2 process for organic precursors.
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