Laboratory studies demonstrated that the floc foam flotation techniques are effective in removing lead, cadmium, mercury, copper, zinc, arsenic, and fluoride from dilute wastewaters to very low levels. Simulated as well as real industrial wastewaters were studied. Industrial wastewaters studied originated from primary aluminum smelters, secondary lead smelters, and brass mills. Copper, lead and arsenic are readily removed with Fe(OH)3 and sodium lauryl sulfate; fluoride and zinc, with Al(OH)3 and sodium lauryl sulfate; cadmium and mercury, with CuS and hexadecyltrimethylammonium bromide. Batch techniques as well as continuous flow systems were used; the latter proved to be more efficient. Possibility of surfactant recovery was investigated. Flotation column simulator computer program was also constructed. Floc foam flotation techniques are not suitable for treatment of wastes containing high concentrations of dissolved salts and adequate pH control is essential in most separations. Foam separation processes combine the attractive features of simplicity, economy, potential for recovery, and effective removal of pollutants at low concentrations in wastewaters.

EPA-600/2-77-072. Includes bibliographical references (pages 54-60).