A comparative study of the effects of ozonation and TiO₂-catalyzed ozonation on the selected chlorine disinfection by-product precursor content and structure
2012
Molnar, Jelena J. | Agbaba, Jasmina R. | Dalmacija, Božo D. | Klašnja, Mile T. | Dalmacija, Milena B. | Kragulj, Marijana M.
This study compares the effects of ozonation (0.4–3.0mgO₃/mg DOC) and TiO₂-catalyzed ozonation — TiO₂–O₃ (0.4–3.0mgO₃/mg DOC; 1.0mgTiO₂/L) at pH 6 on the content and structure of natural organic matter (NOM) and trihalometane (THM) and haloacetonitrile (HAN) precursors in groundwater. The investigated groundwater from Northern Serbia is rich in NOM (9.85mg/L DOC) which is mostly of hydrophobic character (65% fulvic acid and 14% humic acid fraction). It was found that the TiO₂-catalyzed process, by favoring the radical mechanism of NOM oxidation, resulted in a more effective reduction in the content of total NOM (up to 18% DOC) compared to ozonation alone (up to 6% DOC). The use of TiO₂ also resulted in an improvement of ozonation in terms of THM precursor content removal (up to 80%). On the other hand, the application of both oxidation treatments resulted in an increase in the HANFP compared to the raw water. NOM oxidation during ozonation and TiO₂–O₃ caused changes in their structure in the direction of an increased proportion of the hydrophilic fraction (up to 70%), which has the most reactive THM and HAN precursors, as well as the fraction with the highest content of their brominated species.
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