Removal of cyanobacterial blooms in Taihu Lake using local soils.: I.: Equilibrium and kinetic screening on the flocculation of Microcystis aeruginosa using commercially available clays and minerals

Algal removal abilities of 26 clays/minerals were classified into three categories according to the 8-h equilibrium removal efficiency (Q(8h)) and removal rate at a clay loading of 0.7 g/L. Type I clays (sepiolite, talc, ferric oxide, and kaolinite) had a Q(8h) > 90%, a t(50) (time needed to remove 50% of the algae) < 15 min, and a t(80) < 2.5 h. Type 11 clays (6 clays) had a Q(8h), 50-90%, a t(50) < 2.5 h, and a t(80) > 2.5 h. Type III clays (14 clays) with Q(8h) < 50%, t(50) > 8 h and t(80) > 14 h had no practical value in removal of algal blooms. When the clay loading was reduced to 0.2 g/L, Q(8h) for all the 25 materials decreased to below 60%, except for sepiolite whose Q(8h) remained about 97%. The high efficiency for sepio\lite to flocculate M. aeruginosa cells in freshwaters was due to the mechanism of netting and bridging effect. (c) 2005 Elsevier Ltd. All rights reserved.