Use of fluorescence EEM to monitor the removal of emerging contaminants in full scale wastewater treatment plants

This study investigated the applicability of different techniques for fluorescence excitation/emission matrices data interpretations, including peak-picking method, fluorescence regional integration and PARAFAC modelling, to act as surrogates in predicting emerging trace organic compounds (ETOrCs) removal during conventional wastewater treatments that usually comprise primary and secondary treatments. Results showed that fluorescence indexes developed using alternative methodologies but indicative of a same dissolved organic matter component resulted in similar predictions of the removal of the target compounds. The peak index defined by the excitation/emission wavelength positions (λex/λem) 225/290 nm and related to aromatic proteins and tyrosine-like fluorescence was determined to be a particularly suitable surrogate for monitoring ETOrCs that had very high removal rates (average removal >70%) (i.e., triclosan, caffeine and ibuprofen). The peak index defined by λex/λem = 245/440 nm and the PARAFAC component with wavelength of the maxima λex/λem = 245, 350/450, both identified as humic-like fluorescence, were found remarkably well correlated with ETOrCs such as atenolol, naproxen and gemfibrozil that were moderately removed (51–70% average removal). Finally, the PARAFAC component with wavelength of the maxima λex/λem = <240, 315/380 identified as microbial humic-like fluorescence was the only index correlated with the removal of the antibiotic trimethoprim (average removal 68%).