COAGULATION OF COLLOIDAL PARTICLES IN WATER BY CHITOSAN

The feasibility of applying chitosan, as prepared from the crab chitin , was assessed in this study for the coagulation of colloidal particle s. A series of batch flocculation tests with chitosan under different conditions was also conducted. The results indicate that chitosan is a potent coagulant for bentonite suspension. The relationship between t he optimum chitosan dosage and the turbidity of the bentonite suspensi on is presented as a linear correlation. The evidence infers that an a dequate range of the coagulant dosage is the primary consideration in determining the removal efficiency for the turbidity of the source wat er. It also indicates that the coagulation behavior for kaolinite by c hitosan is different from that of bentonite, i.e., chitosan fails to f orm a good aggregate with kaolinite. Turbid water containing particles which show behavior similar to kaolinite apparently need to have some bentonite particles added as coagulant aid, thereby improving the agg regation of the colloid particles with chitosan. Moreover, the effect of pH on the coagulation efficiency of chitosan is insignificant. The evidence infers that charge neutralization is not a major mechanism co ntrolling the formation of flee for chitosan coagulation.