HYDRAULICS OF FLOCCULATION

Abstract

Process of Flocculation aims at achieving removal of fine particles by agglomerating them into flocs with optimal settling velocity. Agitation of dispersion medium increases contact op~rtunities for the fine particles and promotes the growth of flocs . But the velocity gradients set up across the flow paths produce shear which may restrict this growth. Basic principles involved in identifying, maintaining. and reproducing the desirable flow patterns are presented in the study. Normally mechanical flocculators uith .rotating paddles are erployed to set up the desirable patterns. Eat.. perimental work was carried out with six specially designed small paddies to study the effect of percentage area, paddle edge length,,. width of paddle blades and openings and range of variation of velocity gradients on the process of floccu.- lationo Based on critical review... the literature and results of the experimental work carried, out,. recommendations have been made for obtaining a suitable paddle .design. A dimensionless parameter designated as. Flocculation Number has been proposed which should serve as a. criteria for paddle design and an index for flocculation control'.