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The development of a real-time monitoring tool for the estimation of water quality is essential for efficient management of river pollution in urban areas. The Gap River in Korea is a typical urban river, which is affected by the effluent of a wastewater treatment plant (WWTP) and various anthropogenic activities. In this study, fluorescence excitation-emission matrices (EEM) with parallel factor analysis (PARAFAC) and UV absorption values at 220 nm and 254 nm were applied to evaluate the estimation capabilities for biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total nitrogen (TN) concentrations of the river samples. Three components were successfully identified by the PARAFAC modeling from the fluorescence EEM data, in which each fluorophore group represents microbial humic-like (C1), terrestrial humic-like organic substances (C2), and protein-like organic substances (C3), and UV absorption indices (UV220 and UV254), and the score values of the three PARAFAC components were selected as the estimation parameters for the nitrogen and the organic pollution of the river samples. Among the selected indices, UV220, C3 and C1 exhibited the highest correlation coefficients with BOD, COD, and TN concentrations, respectively. Multiple regression analysis using UV220 and C3 demonstrated the enhancement of the prediction capability for TN.

Fluorescence excitation emission matrices-parallel factor analysis (EEM-PARAFAC) is a powerful tool for characterizing dissolved organic matter (DOM), and it is applied in a rapidly growing number of studies on drinking water and wastewater treatments. This paper presents an overview of recent findings about the occurrence and behavior of PARAFAC components in drinking water and wastewater treatments, as well as their feasibility for assessing the treatment performance and water quality including disinfection by-product formation potentials (DBPs FPs). A variety of humic-like, protein-like, and unique (e.g., pyrene-like) fluorescent components have been identified, providing valuable insights into the chemical composition of DOM and the effects of various treatment processes in engineered systems. Coagulation/flocculation-clarification preferentially removes humic-like components, and additional treatments such as biological activated carbon filtration, anion exchange, and UV irradiation can further remove DOM from drinking water. In contrast, biological treatments are more effective for protein-like components in wastewater treatments. PARAFAC components have been proven to be valuable as surrogates for conventional water quality parameter, to track the changes of organic matter quantity and quality in drinking water and wastewater treatments. They are also feasible for assessing formations of trihalomethanes and other DBPs and evaluating treatment system performance. Further studies of EEM-PARAFAC for assessing the effects of the raw water quality and variable treatment conditions on the removal of DOM, and the formation potentials of various emerging DBPs, are essential for optimizing the treatment processes to ensure treated water quality.

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Changes in selected spectroscopic and chromatographic characteristics of water-soluble organic matter (WSOM) extracted from leaf litter and its ability to bind pyrene were monitored throughout 14 day microbial incubation experiments. To provide additional insight into the microbial transformation of the WSOM, incubation experiments were similarly conducted with controlled-composition mixtures of glucose and dissolved humic substances (HS) that were base extracted from the same leaf litter source. Microbial transformation increased the specific ultraviolet absorbance and number-average molecular weight of residual WSOM while polydispersity values decreased. Fluorescence measurements revealed loss of protein-like fluorescence and enhancement of fulvic- and humic-like fluorescence in residual WSOM. Overall, the incubation results suggest that nonaromatic and smaller sized carbon structures were being degraded while the microbial activity produced humic-like aromatic components in solution. Together, these changes resulted in enhanced pyrene binding by the altered WSOM. Consistent findings resulted from mixtures of glucose and the leaf litter HS. Changes in measured operational descriptors were more pronounced for mixtures containing a higher percentage of glucose, suggesting that utilization of labile constituents may be necessary for formation of unknown structures associated with high pyrene binding capabilities. Simple mass balance, end member mixing models often failed to predict changes in pyrene binding brought about by microbial transformation, suggesting that microbial utilization of labile constituents is not the predominant process governing the enhanced pyrene binding.