The interplay between natural organic matter and bromide on bromine substitution

Mahmut S Ersan; Chao Liu; Gary Amy; Tanju Karanfil

doi:10.1016/j.scitotenv.2018.07.384

The interplay between natural organic matter and bromide on bromine substitution

Sci Total Environ. 2019 Jan 1:646:1172-1181. doi: 10.1016/j.scitotenv.2018.07.384. Epub 2018 Jul 29.

Authors

Mahmut S Ersan¹, Chao Liu¹, Gary Amy¹, Tanju Karanfil²

Affiliations

¹ Department of Environmental Engineering and Earth Sciences, Clemson University, Anderson, SC 29625, USA.
² Department of Environmental Engineering and Earth Sciences, Clemson University, Anderson, SC 29625, USA. Electronic address: tkaranf@clemson.edu.

PMID: 30235603
DOI: 10.1016/j.scitotenv.2018.07.384

Abstract

This study examined the interplay between bromide and DOM characteristics, described with SUVA₂₅₄, in terms of formation and speciation of selected DBPs [trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles (HANs)] during chlorination under various water treatment conditions. Cytotoxicity evaluations were also conducted based on the types and amounts of DBPs formed and their corresponding cytotoxicity index values. The results showed that the formation of THMs and HAAs increased as the specific UV absorbance at 254 nm (SUVA₂₅₄) of the waters increased; however, there was no clear trend for HANs. THM and HAN formation increased with increasing bromide levels, while there was no bromide effect on the HAA formation. Lower HAA5 (monochloroaceticacid, monobromoaceticacid, dichloroaceticacid, trichloroaceticacid, dibromoaceticacid) to HAA9 (monochloroaceticacid, monobromoaceticacid, dichloroaceticacid, trichloroaceticacid, dibromoaceticacid, bromochloroaceticacid, bromodichloroaceticacid, dibromochloroaceticacid, tribromoaceticacid) ratios, independent of SUVA₂₅₄, were observed with increasing bromide levels. Bromine substitution factor (BSF) values were in the order of BSF_DHAN > BSF_THAA > BSF_THM ≈ BSF_DHAA. BSF values for all class of DBPs decreased with increasing SUVA₂₅₄. TOX formation increased with increasing SUVA₂₅₄ without an impact of bromide concentration. UTOX/TOX ratios were higher in treated low SUVA₂₅₄ waters than raw waters having higher SUVA₂₅₄ values, and they decreased with increasing initial bromide concentration in all sources. Increasing bromide concentration from 0.5 μM to 10 μM elevated the calculated cytotoxicity index values of waters. Despite their much lower (approximately ~10 times) formation as compared to THMs and HAAs, HANs controlled the calculated cytotoxicity of studied waters.

Keywords: Bromine substitution; Disinfection byproducts; Dissolved organic matter; Haloacetic acids; Haloacetonitriles; Trihalomethanes.