Using fluorescence spectroscopy EEM to evaluate the efficiency of organic matter removal during coagulation–flocculation of a tropical surface water (Agbo reservoir)

Abstract

This study evaluate the use of fluorophores A, C and T fluorescence intensities to access the coagulation efficiency for removing dissolved organic carbon (DOC) in the raw water from Agbo reservoir in Ivory Coast. A coagulation–flocculation was conducted with aluminium sulphate as coagulant and DOC residual and fluorescence intensities were acquired. The consistency of fluorescence data was evaluated to ensure that no inner-effect, quenching or enhanced intensities affect the data. Fluorescence-inferred DOC removal was then calculated in percentage terms from the decrease in organic matter fluorescence intensity for each peak between raw and clarified water and correlated with measured DOC removal. The results indicate a high significant correlation between measured DOC removal and fluorescence-inferred DOC removal calculated for peak A ( R 2 = 0.91), peak C ( R 2 = 0.89), peak T ( R 2 = 0.92) indicating a strong linear relationship between DOC removal and fluorescence intensities. Furthermore, tryptophan-like (peak T) was found to be the least eliminated and thus, may be considered as an indicator of DOC residual after coagulation–flocculation process. This result shows that fluorescence spectroscopy offers a robust analytical technique to be used to evaluate DOM removal efficiency in water treatment.