Effects of Adsorbed Organic Matter on Size, Structure and Filterability of Iron Oxyhydroxide Flocs

In this study, the effects of adsorbed fulvic acid, a naturallyoccurringorganic acid, on the aggregation and filtration of hematite particles are investigated. The study of aggregate structure shows that the fractal dimensions of hematite aggregates which are partially coated with fulvic acid molecules are higher than those obtained with no adsorbed fulvic acid. The high fractal dimensions are due to restructuring within the aggregates, which only occurred at low coverage by the organic acid. In the filtration experiments, high clean filter efficiency was obtained for particles with the net charge opposite to the filter media. During ripening period, however, the particle sizesplayed a more important role than the surface chargesParticles of a micron size seemed to have less capture efficiency during this period, since they are controlled neither by diffusion nor interception.