title: Effect of advanced oxidation on N-nitrosodimethylamine (NDMA) formation and microbial ecology during pilot-scale biological activated carbon filtration.
abstract: Water treatment combining advanced oxidative processes with subsequent exposure to biological activated carbon (BAC) holds promise for the attenuation of recalcitrant pollutants. Here we contrast oxidation and subsequent biofiltration of treated wastewater effluent employing either ozone or UV/H2O2followed by BAC during pilot-scale implementation. Both treatment trains largely met target water quality goals by facilitating the removal of a suite of trace organics and bulk water parameters. N-nitrosodimethylamine (NDMA) formation was observed in ozone fed BAC columns during biofiltration and to a lesser extent in UV/H2O2fed columns and was most pronounced at 20 min of empty bed contact time (EBCT) when compared to shorter EBCTs evaluated. While microbial populations were highly similar in the upper reaches, deeper samples revealed a divergence within and between BAC filtration systems where EBCT was identified to be a significant environmental predictor for shifts in microbial populations. The abundance of Nitrospira in the top samples of both columns provides an explanation for the oxidation of nitrite and corresponding increases in nitrate concentrations during BAC transit and support interplay between nitrogen cycling with nitrosamine formation. The results of this study demonstrate that pretreatments using ozone versus UV/H2O2impart modest differences to the overall BAC microbial population structural and functional attributes, and further highlight the need to evaluate NDMA formation prior to full-scale implementation of BAC in potable reuse applications.
authors.affiliation: NSF Engineering Research Center ReNUWIt, Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA.
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.affiliation: Hazen and Sawyer, Raleigh, NC, USA. Electronic address: bstanford@hazenandsawyer.com.
authors.forename: Ben
authors.initials: B
authors.lastname: Stanford
authors.affiliation: NSF Engineering Research Center ReNUWIt, Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA; Water Quality Research and Development Division, Southern Nevada Water Authority, Henderson, NV 89015, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Dickenson
authors.affiliation: Hazen and Sawyer, Raleigh, NC, USA.
authors.forename: Wendell O
authors.initials: WO
authors.lastname: Khunjar
authors.affiliation: NSF Engineering Research Center ReNUWIt, Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA.
authors.forename: Carissa L
authors.initials: CL
authors.lastname: Homme
authors.affiliation: Hazen and Sawyer, Raleigh, NC, USA.
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Rosenfeldt
authors.affiliation: NSF Engineering Research Center ReNUWIt, Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA. Electronic address: jsharp@mines.edu.
authors.forename: Jonathan O
authors.initials: JO
authors.lastname: Sharp
mesh_terms: D002606:Charcoal; D004128:Dimethylnitrosamine / Q000737:chemistry*; D005374:Filtration; D006861:Hydrogen Peroxide / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification
chemical_list: D014874:Water Pollutants, Chemical; D002606:Charcoal; D010126:Ozone; D006861:Hydrogen Peroxide; D004128:Dimethylnitrosamine
keywords: Advanced oxidation; Biofiltration; Biological activated carbon; Indirect potable reuse; N-nitrosodimethylamine