On the use of fluorescence measurements to characterize wastewater

This paper examines the correlations between some water quality parameters and fluorescence intensities and spectra in filtered wastewater using a 280 nm excitation wavelength. We did not obtain satisfying linear relationships between fluorescence and COD or TOC (r2 approximately 0.4) for any of the emission wavelengths used between 320 and 400 nm (especially at 355 nm, the average emission lambda(max.)). The relationships with NK were better (r2 approximately 0.7); leading us to suggest that one evaluates mainly the organic nitrogen content at lambda(ex.) = 280 nm. Whole spectra processing did not improve the correlations. Gel permeation chromatography yielded markedly different TOC and fluorescence chromatograms, which explains the difficulty of correlating organic content and fluorescence. Other investigations are necessary before spectrofluorimetry can be used as a reliable technique for on-line wastewater pollution estimation.