Removal of cyanobacterial blooms in Taihu Lake using local soils.: II.: Effective removal of Microcystis aeruginosa using local soils and sediments modified by chitosan

After sepiolite was modified with Fe3+ to increase its surface charge, the initial algal removal rate increased significantly, but its Q(8h) was not improved substantially at clay loadings below 0.1 g/L. Modification on netting and bridging properties of clays by either chitosan or polyacrylamide (PAM) dramatically increased flocculation (Q(8h)) of MA cells in freshwaters. Algal removal efficiencies of different solids, including Type 111 clays, local soils and sediments, were all improved to a similar level of > 90% at a total loading of 0.011 g/L (contained 0.001 g/L chitosan) after they were modified with chitosan, making the idea of clearing up algal blooms using local soils/sediments possible. The mechanism of netting and bridging was confirmed to be the most important factor in improving the removal efficiency of cells, whereas clays also played important roles in the sedimentation of the floc. (c) 2005 Elsevier Ltd. All rights reserved.