C-, N-DBP formation and quantification by differential spectra in MBR treated municipal wastewater exposed to chlorine and chloramine

Formation of various carbonaceous and nitrogenous disinfection by-products (DBPs) during chlorine and monochloramine disinfection of recycled municipal wastewater produced by membrane bioreactor (MBR) was studied and quantified using differential ultraviolet (UV) absorbance and fluorescence spectral parameters. Chlorination resulted in extremely high yields of trihalomethanes (THMs) and haloacetonitriles (HANs). Monochloramine disinfection decreased total halogenated DBP yields by one order of magnitude, while doubled the N-nitrosodimethylamine (NDMA) formation. Extending reaction time increased DBP formation. The differential log-transformed UV spectral parameters including DLnA(350) (differential logarithm of absorbance at 350 nm) and DSloop(300-340) (slope differential of the log-transformed spectra at wavelength range 300-340 nm), and differential Excitation/Emission Matrix (EEM) fluorescence spectral parameters including DI(lambda(280 lambda 310)) (differential fluorescence intensity for proteins) and D Phi(i,n) (i = T, II and III; differential of integrated EEM intensities for gross DOM, humic acid-like and fulvic acid-like components) had strong exponential correlations to THM4 formation (R-2 > 0.99) and linearly correlated to HAN(4) yield during disinfection of MBR effluents. It indicated that THM and HAN formation was related to the halogenation of proteins and humic substances. No quantitative correlation was found between NDMA yields and the studied spectroscopic parameters. (C) 2016 Elsevier B.V. All rights reserved.