Use of Azo dyes, having one or more azo bond (-N=N-), are more than 70% among all textile dyes used. The stability and the xenobiotic nature of reactive of these azo dyes make them recalcitrant and hence they are not totally degraded by conventional wastewater treatment processes that involve physical, chemicals or activated sludge methods.  The dyes are therefore released into the environment, in the form of colored waste water.  Color of the waste effluent is an important parameter for a long time. So the main criteria of removing the waste and degrade is to first remove the color of the effluent.  Some common techniques which are used for degrading the chemically complex dye have several harmful side effects and they   are not very cost effective and some require long retention time.  So extensive research is going on to find a simple method which should obviously be a low cost process, will need less time to complete the process and will have minimum harmful side effects.