Treatment of low turbidity water by sweep coagulation using bentonite

A novel strategy of sweep coagulation to treat low turbidity water is presented herein. Study findings demonstrated that an Na+-saturated bentonite with medium cation exchange capacity (CEC) resulted in significant turbidity removal at a bentonite dosage of 30 mg dm(-3). Bentonite dispersion with fully delaminated platelets tended to undergo a more porous type of coagulation with intense face-to-face interactions of platelets and effectively entrapped TiO2 particles in band-type structures. This type of coagulation usually results in a large volume of settled flocs with a fluffy structure and excellent turbidity removal efficiency for sweep coagulation. The sign and magnitude of electrical charge on TiO2 particles has a minor effect on the efficiency of sweep coagulation. (c) 2005 Society of Chemical Industry