As analytical methods for water contaminants continue to evolve and broaden, so does the suite of disinfection byproducts (DBPs). Today, more than 600 disinfection byproducts (DBPs) have been reported in scientific literature while only 11 are regulated by the US EPA. Granular activated carbon (GAC) is commonly employed to reduce DBP precursors, but only limited research has been conducted to evaluate the effectiveness of GAC for the control of emerging carbonaceous (C-) and nitrogenous (N-) DBPs. Here we investigate the role pre-oxidation (i.e., chlorination and ozonation) has on GAC filtration for treatment of tertiary wastewater containing various ambient DBPs (formed during pre-oxidation) and C- and N-DBP precursors (quantified by both the maximum formation potential (FP) and uniform formation conditions (UFC)). Pilot-scale testing have been conducted using three parallel GAC columns operated at 5 gpm/ft<sup>2</sup> and 10 min empty bed contact time: (i) one with pre-chlorination, (ii) one with pre-ozonation, and (iii) one with no pre-oxidation. The various ambient regulated [i.e., trihalomethanes (THM4), haloacetic acids (HAA5), and bromate] and unregulated DBPs (i.e., N-nitroso compounds, including N-nitrosodimethylamine) and precursors were monitored over time. Results indicate that using GAC filtration performs best after oxidation (chlorination &gt; ozonation &gt; no oxidation) for the removal of THM precursors. Whereas, of the three processes, ozone in combination with GAC is the most impactful at lowering HAA and NDMA precursors. This study provides better understanding of the application of GAC with various pre-oxidation practices for the control of regulated and emerging DBPs and their precursors. Ultimately, GAC can be a powerful addition in treatment processes to minimize regulated and emerging DBPs for multiple final disinfection strategies applied for potable reuse.

Impact of pre-oxidation on the removal of regulated and emerging disinfection byproducts by activated carbon

253rd National Meeting (2017)

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