Emerging applications of EEM-PARAFAC for water treatment: a concise review

In this work, the application of EEM-PARAFAC (fluorescence excitation-emission matrix-parallel factor analysis) in water treatment processes, has been summarized. First, its most common use, the characterization and monitoring of dissolved organic matter (DOM) along freshwater ecosystems, drinking and wastewater treatment plants (DWTP and WWTP, respectively), was reviewed. In particular for DWWT/WWTP, the effect towards the different DOM fractions after adsorption, coagulation, biological/chemical processes or tertiary treatments (e.g. advanced oxidation processes), as well as the PARAFAC components scores (i.e. fluorescence intensity) correlation with disinfection by-products formation, were reported. On the other hand, barely barely for the first time, we also reviewed the emerging uses of EEM-PARAFAC focused on water treatment studies, such as, the simultaneous analysis of several fluorescent CECs degradation (with the concomitant formation of major by-products), the use of PARAFAC components scores decay to estimate certain CECs removals, the correlation of reactive oxygen species formation with the specific DOM fractions originating them, or even the study of interactions between DOM with other water constituents. Therefore, this study aims to extend the uses of this economical, reagentless and low time-consuming tool to obtain further insight into fluorescent compounds during water treatment processes, mainly to: i) tentatively elucidate structural modifications of target analyte (DOM or CECs), ii) obtain semi-quantitative data on parent pollutants and by-products variation, and iii) investigate the plausible mechanistic aspects which are involved.