Use of continuous flocculation monitoring in the control of water treatability parameters

ABSTRACT

In this article, a continuous flocculation-monitoring equipment (CFME) was employed to better understand coagulation and flocculation in the treatment of synthetic water under different coagulation mechanisms, on a bench scale. The study water used in the tests was prepared in the laboratory with the addition of a solution of kaolinite in water. Liquid aluminum sulfate, free from iron, was used as a coagulant agent. The flocculation index (FI) measured over time was able to identify the regions of floc growth, plateau and decay. FI was found to be an adequate parameter for optimizing flocculation pH and coagulant dosage. Optimum pH and dosage, obtained in jar tests, were related to the largest variations in FI. The mean FI was found to be adequate for predicting optimum coagulant dosage in the first three minutes after flocculation, whereas the slope of the best-fit FI line was found to be suited for predicting flocculation kinetics.

Keywords:
water treatment; flocculation; flocculation index; continuous monitoring