Electrophoretic Studies of Coagulation for Removal of Organic Color

platinum-cobalt scale. Most municipalities, however, endeavor to maintain lower concentrations, on the order of 10 or even less. Many industrial users, of which the pulp and paper industry is possibly the best example, require waters with low concentrations of color. For the production of highbrightness bleached pulp and paper, the maximum concentration of color tolerated is usually 5 or less. In many areas of the United States where the prevailing aquifers are limestones and where solution-type topoggraphy permits high recharge of surface water, considerable concentrations of organic color may be present in water from both deep and shallow wells. In such instances, lime-soda softening has been shown to remove a substantial amount of the color, particularly in waters with high concentrations of magnesium. The concentration of organic color in water from more than twenty wells supplying the Hialeah plant at Miami, Fla., is reduced to 5-8 by lime softening followed by free residual chlorination. Organic color, however, is more characteristic of soft surface waters of low alkalinity and, consequently, of low buffer capacity. The most common method of color