Using Modified Bentonite Coagulation-acidation for COD and Color Removal from Scouring Effluent

In this work, chemical oxygen demand (COD) removal and decolorization of polyester scouring effluent by coagulation-acidation have been studied experimentally. Acidulated bentonite was used as coagulant. The effects of bentonite dosage, PAM dosage, stirring time, and pH after acidation on the efficiency of COD and color reduction were studied by orthogonal methodology. Finally the optimum conditions have been obtained. The products of coagulation and acidation were test by Fourier transform infrared spectra. It has been concluded that the most of residual color and suspended solid are removed during the coagulation process and the acidation product is terephthalic acid. Under the optimum condition, the removal efficiencies of COD and color are 79.7% and 90%, respectively.