FILTRATION OF SUBMICRON PARTICLES - EFFECT OF IONIC-STRENGTH AND ORGANIC-SUBSTANCES

Hematite (alpha-Fe2O3) suspension was used in this study to investigat e the effects of aggregate size and solution chemical characteristics on particle removal and headless development in a deep bed filter. Whe n electrolyte (KCl) concentration in the suspension was increased from 0-80 mM, the size of hematite aggregates in suspension increased from 85 to 990 nM but had no significant effect on zeta potential. It was found that at low KCl concentrations (0-10 mM), the initial removal is governed by surface chemical properties while at higher concentration s (40-80 mM), the effect of particle size (steric effect) predominates . The transient stage filter performance was found to be controlled by the favourable chemical conditions prevailing in the filtration syste m rather than the size of the particles.