Towards reducing DBP formation potential of drinking water by favouring direct ozone over hydroxyl radical reactions during ozonation

WATER RESEARCH

卷:87

Article

De Vera, Glen Andrew¹  Stalter, Daniel^2,5  Gernjak, Wolfgang^1,3  Weinberg, Howard S.⁴  Keller, Jurg¹  Jose Farre, Maria^1,3 

[1] Univ Queensland, Adv Water Management Ctr, Brisbane, Qld 4072, Australia

[2] Univ Queensland, Natl Res Ctr Environm Toxicol Entox, Brisbane, Qld 4108, Australia

[3] Univ Girona, ICRA, Catalan Inst Water Res Sci & Technol Pk, Girona 17003, Spain

[4] Univ N Carolina, Dept Environm Sci & Engn, Chapel Hill, NC 27599 USA

[5] Swiss Fed Inst Aquat Sci & Technol EAWAG, CH-8600 Dubendorf, Switzerland

关键词: Ozonation;    Hydroxyl radicals;    Disinfection byproducts;    Adsorbable organic halogens;    In vitro bioassays;   

DOI  :  10.1016/j.watres.2015.09.007

来源: Elsevier

【 摘 要 】

When ozonation is employed in advanced water treatment plants to produce drinking water, dissolved organic matter reacts with ozone (O-3) and/or hydroxyl radicals ((OH)-O-center dot) affecting disinfection byproduct (DBP) formation with subsequently used chlorine-based disinfectants. This study presents the effects of varying exposures of O-3 and (OH)-O-center dot on DBP concentrations and their associated toxicity generated after subsequent chlorination. DBP formation potential tests and in vitro bioassays were conducted after batch ozonation experiments of coagulated surface water with and without addition of tertiary butanol (t-BuOH, 10 mM) and hydrogen peroxide (H2O2, 1 mg/mg O-3), and at different pH (6-8) and transferred ozone doses (0-1 mg/mg TOC). Although ozonation led to a 24-37% decrease in formation of total trihalomethanes, haloacetic acids, haloacetonitriles, and trihaloacetamides, an increase in formation of total trihalonitromethanes, chloral hydrate, and haloketones was observed. This effect however was less pronounced for samples ozonated at conditions favoring molecular ozone (e.g., pH 6 and in the presence of t-BuOH) over (OH)-O-center dot reactions (e.g., pH 8 and in the presence of H2O2). Compared to ozonation only, addition of H2O2 consistently enhanced formation of all DBP groups (20-61%) except trihalonitromethanes. This proves that 'OH-transformed organic matter is more susceptible to halogen incorporation. Analogously, adsorbable organic halogen (AOX) concentrations increased under conditions that favor (OH)-O-center dot reactions. The ratio of unknown to known AOX, however, was greater at conditions that promote direct O-3 reactions. Although significant correlation was found between AOX and genotoxicity with the p53 bioassay, toxicity tests using 4 in vitro bioassays showed relatively low absolute differences between various ozonation conditions. (C) 2015 Elsevier Ltd. All rights reserved.

【 授权许可】

Free