Correlation between MFT and Suspended Matter in Seawater

Abstract

An investigation was carried out on the correlation between the MFT (membrane filtration time) of seawater and the particles on the membrane filter surface. The MFT was compared with the conventional indexes of suspended solid such as the turbidity and the dry weight of the particles. The particles were analyzed by X-ray fluorescence spectroscopy, scanning electron microscopy and electron probe microanalyses.
The results indicated that there were two major groups which influenced the MFT in the seawater. One was inorganic particles composed of alminosilicate compounds and diatomous which were suspended solid detectable as turbidity or dry weight. The other was assumed to be colloidal and/or soluble organics which could not be represented by such ordinary values. There was found a relatively good correlation between the turbidity and the dry weight, while the correlations between the MFT and these values were not very good, especially for the low turbidity region. The organic compound was assumed to be related to the viscous liquid matter which came from seaweed and might have a surface activity. It was considered that this surfactant might have a possibility of increasing the filtration resistance of membrane filter by adsorption. Therefore, the MFT was greatly influenced by these organic components when the turbidity of seawater was on a relatively low level. This meant that the MFT could increase even when not much suspended solid existed.