Samples taken at different points in the wastewater treatment process of a triazine-manufacturing plant were scanned by fluorescence spectroscopy, in the wavelength range of 200-900 nm. Reproducibly, the fluorescence spectra revealed one single major peak at excitation and emission wavelengths of 258 and 370 nm respectively. Aqueous solutions of purified active compounds, including Atrazine, Propazine, Simazine, Terbuthylazine, Metolachlor, and Benoxacor, were also scanned. No significant fluorescence was observed in these standard solutions at concentrations up to 100 mg/L. Selected plant samples as well as standard solutions of Atrazine, Metolachlor, and toluene were further analyzed using high-performance liquid chromatography with absorbance and fluorescence detections. Pure Atrazine was found to be light-absorbing but nonfluorescent while Metolachlor, with a benzene ring in its structure, was weakly fluorescent. The plant wastewater samples exhibited a single strong fluorescence peak, which also appeared as the dominant peak in the fluorescence chromatogram of Atrazine standard (due to impurity). The findings strongly suggested that the responsible fluorescent compound in the plant\u27s wastewater was a byproduct of the synthesis processes. The fluorescent compound was found to be effectively removed by the carbon adsorption treatment (CAT) unit employed in the plant but not by the biological activated-sludge treatment process alone. The results indicated the feasibility of using online fluorescence measurements to effectively monitor the performance of the CAT unit
