GAC Removal of Organic Nitrogen and Other DBP Precursors (PDF)
- Author(s): Chiu, Chao-An; Westerhoff, Paul; Ghosh, Amlan
- Publications: Journal - American Water Works Association
- Issue Date: July 2012
- Volume / Number: 104, Number 7
- Page(s): E406-E415
- DOI: http://dx.doi.org/10.5942/jawwa.2012.104.0090
- Product Number: JAW_0076145
Non-Member Price: $0
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The increased mutagenicity of disinfection byproducts (DBPs) containing bromide (Br-) and nitrogen requires a renewed evaluation of best available treatment technologies for DBP control. The aim of this article is to document the removal of organic nitrogen during granular activated carbon (GAC)
treatment and to illustrate how GAC treatment alters DBP speciation. Rapid small-scale column tests (RSSCTs) with GAC were conducted on pretreated surface water sources to evaluate the simultaneous removal of carbonaceous and nitrogenous DBP precursors: dissolved organic nitrogen (DON), dissolved organic carbon (DOC), organics absorbed by ultraviolet light at 254 nm (UV254), and Br-. Simulated distribution system tests were conducted with RSSCT effluent samples throughout natural organic matter breakthrough, and free chlorine was used to evaluate the formation of halogenated carbonaceous and nitrogenous DBPs. GAC preferentially removed UV254-absorbing material over DOC, which was removed more effectively than DON. Br- was not removed. Consequently, effluent ratios of Br- to DOC and Br- to DON changed during GAC treatment, and the ratio of brominated DBPs to chlorinated DBPs shifted during the GAC breakthrough cycle; brominated DBPs dominated earlier in the breakthrough of DOC. Neither DON nor nitrogenous DBP precursors were removed efficiently during GAC treatment.
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