Flocculation of Chrome-Plating Wastes with Polyelectrolytes

Abstract

One of the largest industries in southeast New England is the metal-finishing industry. Normally a metal is pretreated before the actual finishing step. In these operations there is usually a dip in organic solvents and/or detergents to remove grease, oils, dirt, etc. This is followed by a few rinse baths. The metal is then pickled in a strong acid bath, rinsed again several times, followed by the plating or finishing operation and more rinses. A major problem associated with these industries is the treatment or lack of treatment of the prodigious volumes of waste water from the many rinses. These waste waters contain either acids or alkalies, metal ions (such as Cr, Cu, Zn, Ag, Pb, Fe, and Mn), cyanides, organics, chemical oxygen demand, and a high solids content of dissolved, suspended, and settleable material. Proper treatment can reduce or eliminate the impurities from the waste waters. However, there are usually problems of cost, time, ease of operation, and ultimate disposal of sludges.

This chapter is based on a paper presented to the Division of Water, Air, and Waste Chemistry, American Chemical Society, New York, Aug. 28, 1972.