Method for discoloring printing and dyeing wastewater by using granulated composite bentonite material

The invention relates to a method for discoloring printing and dyeing wastewater by using a granulated composite bentonite material, which comprises the steps of: proportioning, mixing, plasticizing, extruding, cooling and cutting bentonite and thermoplastic high-molecule polymers into short column granules to obtain the granulated composite bentonite material; putting the granulated composite bentonite material together with surface active agent into the printing and dyeing wastewater; oscillation for 10-15min; and then conducting solid-liquid separation, wherein colored dye reacts with the surface active agent to produce flocculation which is removed into solid samples which are filtered and separated. The method has the advantages that the complex preparation method of organic bentonite is omitted, the secondary pollution of the surface active agent is reduced, the discoloring time is short, the discoloring efficiency is high, the solid-liquid separation is easy and the granulated composite bentonite material can be reused. The method is suitable for discoloring colored dye wastewater which contains indicarmine or methyl orange.