The effect of metal ions on the fluorescence of sewage wastewater

Fluorescence spectroscopy has the potential to be used in real-time monitoring of sewage strength for process control in sewage treatment works. However, unpredictable pollution incidents may contribute to a large variation in the metal ion content of sewage. These ions, particularly Cu2+ and Ni2+, have been found to quench the fluorescence of sewage by as much as 40% at a concentration of 0.2 mg/l. The quenching is not pronounced for the fluorescence of the final effluent from sewage plants. The results are explained in terms of possible chelating of the metal ions with the large aromatic hydrocarbons in humic or fulvic substances.