Decolorization of dyeing effluents with composite flocculant

The decolorization of dyeing and finishing effluents with inorganic flocculant,organic flocculant as well as organic and inorganic compound flocculant are studied.The influences of the dosage,pH value and the compound ratio of the flocculants on decolorization effect are discussed.The results show that the compound of the organic polymer and inorganic flocculant can obviously improve the decolorization effect.When the compound flocculant is applied to dyes solution,it appears that different dyes have different decolorization rate and optimal pH value range.The synergistic actions to Direct Red BWS and Acid Red N-3BL are better than that to Reactive Red BF-DB.When the compound flocculant is applied to practical printing and dyeing effluents,the optimum conditions are as follows: the dosages of organic polymer flocculant and aluminum salt flocculant are 120 mg/L and 80 mg/L respectively,and treating at pH value of 6～7.The decolorization rate can reach 96.8% and the removal of COD can reach 80.6%.