Ferric chloride was used as coagulant agent in treatment of Dianchi Lake in order to remove blue algae during algal eruptive period. To do so, a coagulant sedimentation experiment was arranged with L934 orthogonal method. The result showed that the varieties of coagulant agents and pH value of water had great effects on efficiency for the removal of the algae. The best operational parameters to remove blue algae with coagulant sedimentation were optimized. It provided an operational base for industrializati...