Evaluation of drinking water quality and wastewater effluents by fluorescence excitation emission matrix spectroscopy.

摘要

Natural waters and wastewaters contain microorganisms as well as chemical substances of natural and anthropogenic origin. Disinfection of water reduces waterborne diseases, but concomitantly, disinfection by-products (DBP) are formed by the reaction of organic matter (OM) present with the disinfectants used. For drinking water, DBPs of major concern, trihalomethanes (THMs) and haloacetic acids (HAAs), are regulated by the U.S. Environmental Protection Agency because these compounds are suspected of causing human health impairment. In the case of wastewater treated and disinfected, although not regulated, unknown concentrations of DBPs are released to the environment.;Taking advantage that a fraction of the OM exhibit fluorescence properties, this research used the three-dimensional fluorescence spectroscopy or excitation-emission matrix (EEM) spectroscopy of water samples in order to observe fluorophore fingerprints in different types of water, i.e. drinking water, surface waters, industrial and wastewater treated effluents, and correlate the fluorescence corrected intensities with selected water quality surrogates, i.e. dissolved organic carbon (DOC), ultraviolet absorbance at 254 nm (UV254), specific ultraviolet absorbance at 254 (SUVA254), THM formation potential (THMFP), and HAAs formation potential (HAA5FP).;In drinking waters, treated and raw waters from three Tennessee locations---Bristol/Bluff City, Hartsville, and Sewanee---were examined. Specific fluorophores, C (Ex = 216nm, Em = 418nm), D (Ex = 312nm, Em = 414nm), and E (Ex = 216nm, Em = 470nm) and a fluorescence index, i.e. C/D, showed significant correlation (p ≤ 0.05) with some drinking water quality surrogates. SUVA254 and HAA5FP were better predicted than THMFP. Correlations were better within treatments from a specific site rather than taking into account all data.;Wastewater from industries in Memphis, Tennessee and wastewater treatment plant effluents from diverse locations in the USA were studied. From the EEM, nine fluorophores were observed: A (Ex = 222 nm, Em = 308 nm), B (Ex = 273 nm, Em = 312 nm), C (Ex = 224 nm, Em = 353 nm), D (Ex = 273 nm, Em = 357 nm), E (Ex = 224 nm, Em = 418 nm), F (Ex = 338 nm, Em = 421 nm), G (Ex = 224 nm, Em = 460 nm), H (Ex = 344 nm, Em = 462 nm) and I (Ex = 494 nm, Em = 521nm). A and B were classified as tyrosine-like origin; C and D as tryptophan-like; E, F, G and H as humic-like; and I was of unknown origin. Wastewaters exhibited differences related to origin and treatment. This research demonstrated the simplicity of the analytical technique, requiring minimal sample volume and treatment, and ease of interpretation of the EEM fluorescence spectra, which make it a promising tool in monitoring organic matter in drinking and wastewaters.