Removal of Natural Organic Matter by Ultrafiltration: Characterisation, Fouling and Cleaning

Organic matter in natural brown water as well as humic acids from a commercial sample were characterised by ultraviolet-visible light-spectroscopy and used in ultrafiltration studies. During ultrafiltration the pure-water flux and the operational flux were measured continuously to determine the degree of membrane fouling. The natural organic matter and commercial humic acid concentrations of the feed and permeate solutions were determined spectrophotometrically. These variables were used in conjunction with conventional flux measurements, to determine the colour-removal efficiency of ultrafiltration as well as the degree of foulant adsorption onto the membranes. Fouled membranes were cleaned with alkaline chemical agents normally used to extract natural organic matter from soil samples. The cleaning efficiency and the effect of cleaning solutions on the membrane selectivity were studied.