Evaluation of innovative water treatments at molecular level based on high resolution mass spectrometry and advanced statistical tools

This work aims at integrating the last advances in high resolution mass spectrometry (HRMS) and statistical analysis to develop and optimize a smart methodology (workflow) for the assessment of the performance of innovative water treatments using different technological approaches based on advanced oxidation processes with UV-254nm: (i) UV/K2S2O8, where oxidation takes place mainly following the initial formation of sulfate radicals, (ii) UV/KHSO5, where oxidation begins with the formation of both sulfate and hydroxyl radicals and (iii) UV/H2O2, when only the formation of hydroxyl radicals takes place initially. Experiments were carried out using secondary effluent from a local wastewater treatment plant. The developed workflow allows the evaluation of the treatments in terms of overall oxidation through the careful study of Van Krevelen diagrams, where all information of the HRMS chromatograms is considered. The potential formation of transformation products with sulfur due to the sulfate radicals was also evaluated using statistical tools based on the accurate mass and the isotopic pattern. In a similar way, the potential addition of halogens was also assessed. Finally, the behavior of a large number of micropollutants with a wide range of physicochemical properties was studied using suspect screening strategies.