Zeta Potential and Its Application to Difficult Waters

THE zeta potential (ZP) is a measure of he electrokinetic charge (expressed in millivolts) that surrounds uspe ded particula e atter. The charge on raw-water turbidity is pr dominantly electronegative, and i sufficiently strong to result in significant utual epulsion. Thus rawwater colloids and protein colloids such as skimme milk remain suspended. If the charge on these particles is reduced to zero, these re ulsive forces are liminated. Gentle mechanical agitation will hen create numerous par icle collisions inst d of nea misses, and the forces of adhesion, cohe ion, m chanical interlocking will result in agglomeration. The ensuing b ildup in particle size t en enables rapid settling in accorda c with Stokes* law. Before ZP is discussed, the nature of raw water colloids and some funda-