A model for predicting dissolved organic carbon distribution in a reservoir water using fluorescence spectroscopy

A number of water treatment works (WTW) in the north of England (UK) have experienced problems in reducing the dissolved organic carbon (DOC) present in the water to a sufficiently low level. The problems are experienced in autumn/winter when the colour increases and the coagulant dose at the WTW needs to be increased in order to achieve sufficient colour removal. However, the DOC content of the water varies little throughout the year. To investigate this further, the water was fractionated using resin adsorption techniques into its hydrophobic (fulvic and humic acid fractions) and hydrophilic (acid and non-acid fractions) components. The fractionation process yields useful information on the changing concentration of each fraction but is time consuming and labour intensive. Here, a method of rapidly determining fraction concentration was developed using fluorescence spectroscopy. The model created used synchronous spectra of fractionated material compared against bulk water spectra and predicted the fraction concentrations to within 10% for a specific water. The model was unable to predict fraction concentrations for waters from a different watershed.