Re‐assessing effects of bromide and granular activated carbon on disinfection byproduct formation

Abstract

While granular activated carbon (GAC) can effectively remove disinfection byproduct (DBP) precursors, its use has raised concerns over the increased formation of some brominated DBP (Br-DBP) species in treated water postchlorination, especially for waters with high bromide concentrations. The Information Collection Rule Treatment Study Database contains the results of the most extensive GAC studies ever conducted nationwide. Data were analyzed to assess the extent of DBP speciation changes and the overall reduction of Br-DBPs by GAC to gain new insights into the bromide effect. Results showed that formation of three brominated trihalomethanes (collectively Br-THM3) varied greatly depending on total organic carbon (TOC) removal and bromide concentrations. Low TOC concentrations in GAC effluents resulted in greatly reduced Br-THM3 formation, except for a few cases where Br-THM3 formation increased. GAC followed by chloramination were likely to better control Br-THM3 formation for waters with high TOC and high bromide. Finally, chlorine demand reduction by GAC was quantified. K E Y W O R D Sbromide, brominated DBPs, GAC, total organic carbon

Evaluating regulatory scenarios to limit U.S. nationwide exposure to cytotoxic haloacetic acids

“…The effectiveness of HAA6Br to target the highly brominated HAAs (and the ineffectiveness of HAA9) has implications for controlling DBP‐associated risk for other types of DBPs that were not measured in UCMR4. It is well‐established that the formation of brominated versus chlorinated DBP species is related to bulk water quality parameters (often expressed as the ratio of bromide to TOC (Summers et al, 1993; Symons et al, 1993; Wang et al, 2019), and as a result, PWS with high concentrations of brominated HAAs are likely to have brominated species of any other co‐occurring DBP classes. This is relevant to exposure because, like HAAs, many classes of DBPs exhibit systematically higher in vitro cyto‐ and geno‐toxicity with increasing bromide substitution (Krasner et al, 2006; Richardson et al, 2007).…”

“…The effectiveness of HAA6Br to target the highly brominated HAAs (and the ineffectiveness of HAA9) has implications for controlling DBP-associated risk for other types of DBPs that were not measured in UCMR4. It is well-established that the formation of brominated versus chlorinated DBP species is related to bulk water quality parameters (often expressed as the ratio of bromide to TOC (Summers et al, 1993;Symons et al, 1993;Wang et al, 2019), and as a result, PWS with high concentrations of brominated HAAs are likely to have brominated F I G U R E 4 Changes in the species composition of HAA9 as a function of HAA9 concentration. Panels group the species that followed similar concentration trends (refer to Figure S4 for individual species).…”