Dyes, Environmental Chemistry

Synthetic organic dyes are essential to satisfy the ever growing demands in terms of quality, variety, fastness, and other technical requirements for coloration of a growing number of substances. Beginning in 1970, however, the dyestuff and textile industries have become increasingly subject to international, federal, and state regulations designed to improve health, safety, and environment. Therefore, in an attempt to provide a perspective of the environmental problems posed by synthetic organic colorants, and the efforts being made by industry, academia, and government to solve these problems, this article includes the physical, chemical, and biological methods of effluent treatment of dye wastewater. Specifically, the physical methods are adsorption, sedimentation, flotation, flocculation, coagulation, foam fractionation, polymer flocculation, reverse osmosis and ultrafiltration, ionization radiation, and incineration; the chemical methods are neutralization, reduction, oxidation, electrolysis, ion exchange, and wet air oxidation; the biological methods are stabilization ponds, aerated lagoons, trickling filters, activated sludge, anaerobic digestion, and bioaugmentation. Also included are fate of dyes, analytical methods, pollution prevention, heavy metals, toxicity, and legislation.