Strict regulations that control the discharge of colored effluents from dyehouses are increasing the use of color removal technologies and leading to the development of new effluent treatments. Conventional color removal techniques comprise four primary categories: activated charcoal, membrane technology, ozone treatment, and coagulation/flocculation. These techniques possess significant differences in color removal results, volume capability, operating speeds, and capital costs. Activated charcoal, for example, is extremely effective for removing color, but is capable of treating only small effluent volumes, operates at slow speeds, and has high capital costs. Membrane technology, ozone treatments, and coagulation/flocculation permit good color removal in large effluent volumes. Membrane technology is fast, but the capital costs for implementing this technology are high. Ozone treatments operate at moderate speeds and also require a high capital investment. Coagulation/flocculation techniques operate at moderate to fast speeds and require a somewhat lower capital investment. New color removal technologies include the use of biological color absorbers, inorganic absorbers, and systems based on electrolysis. 2 refs.