On-line monitoring of NDMA precursors in MBR-NF pilot plant by using fluorescence EEM

Abstract

This study examined the applicability of fluorescence excitation/emission matrices (EEM) as online monitoring tool of N-Nitrosodimethylamine (NDMA) precursors throughout a pilot-scale advanced wastewater treatment train, which included a membrane biological reactor (MBR) followed by nanofiltration (NF). The data were generated using samples of the raw wastewater, MBR effluent, NF feed, NF permeate and NF concentrate collected over a four months period and at varying operating conditions (SRT, etc.). Examination of selected fluorescence and absorbance indices obtained by the weekly plant samples combined with the data of NDMA precursors calculated with the formation potential test showed strong relationships between the NDMAFP and the intensity of specific fluorescence components. In particular, the fluorescence region of the EEM associated with aromatic proteins and tyrosine-like substances was strongly correlated with the NDMA precursors. This result gives insight on the type of NDMA precursors that can be found in domestic wastewater and demonstrate that fluorescence EEM can be used to monitor the concentration of NDMA precursors in situ and in real time during advance wastewater treatment processes such as MBR and NF.