Unique Observation of NDMA Formation Across Biofiltration: Water Research Article Now Available
(RALEIGH, NC – March 1, 2017) – Several Hazen and Sawyer engineers are among the co-authors of an article in the latest issue of Water Research titled “Effect of advanced oxidation on N-nitrosodimethylamine (NDMA) formation and microbial ecology during pilot-scale biological activated carbon filtration”.
Water treatment combining advanced oxidative processes with subsequent exposure to biological activated carbon (BAC) holds promise for the attenuation of recalcitrant pollutants. In this article, the authors contrast oxidation and subsequent biofiltration of treated wastewater effluent employing either ozone or UV/H2O2 followed 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/H2O2 fed 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/H2O2 impart 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.
The full article is available for purchase on the Water Research website.