Colorants – Dyes And Pigments 

Colorants – dyes and pigments  are a growing pollution problem in the industrial and household wastewater as a result of their extensive use and relative stability towards degradation. The dyes, (especially textile dyes) are engineered to be resistant to all kinds of treatments without fading. They need to sustain either alkaline or acidic environment; they need to withstand washing with soaps and bleaching agents, microbiological fading, be resistant to light and ultraviolet irradiation etc.  Obviously, the better stability of dyes achieved in the consumer products, the worse problem they cause in the wastewater stream when subjected to decoloration and degradation