Revealing a Size-Resolved Fluorescence-Based Metric for Tracking Oxidative Treatment of Total N-Nitrosamine Precursors in Waters from Wastewater Treatment Plants

Abstract

N-Nitrosamines make up a nonhalogenated group of disinfection byproducts that form during chloramination, particularly in drinking waters impacted by wastewater treatment plant (WWTP) effluents. Here, we reveal a size-resolved fluorescence-based precursor surrogate for tracking total N-nitrosamine formation potential (TONOFP) through oxidative treatment. Samples were collected at seven WWTPs, at the finished effluent and prior to final disinfection (i.e., secondary effluent). Asymmetric flow field-flow fractionation (AF4) with inline fluorescence detection at excitation and emission wavelengths of 280 and 340 nm, respectively (i.e., I280/340), showed protein-rich natural organic matter peaks between 10–445 and 445–1500 kDa. TONOFP was measured by chemiluminescence on samples dosed with 250 mg L–1 Cl2 monochloramine at pH 7 for 7 days. Metrics from AF4 I280/340 (i.e., area under the curve and peak height) and I257/277 from whole water excitation–emission matrices were leveraged in multivariate models to de...