Treatment of Synthetic Textile Wastewater by Combination of Coagulation/Flocculation Process and Electron Beam Irradiation

Introduction: Textile wastewaters are heavily polluted with dyes and chemicals and have a broad range of pH, high COD concentration and suspended particles. In this study, the efficiency of color and turbidity removal from synthetic textile wastewaters were investigated by a combined process of coagulation/ flocculation and electron beam irradiation. Materials and Methods: The experiments have been done on model dye solution samples, which were prepared from ten dyes supplied from Yazd Baff factory. Aluminum sulphate was employed as coagulant. Then samples were irradiated by electron beam accelerator at different doses. Absorption spectra of the samples were measured using UV-Vis spectrophotometer. The pH and turbidity values of the solutions were measured by a pH meter and turbidimeter. Results: According to results, the degree of decoloration and turbidity removal of synthetic dye solutions increased when the alum concentration increased and reached 64% and 90% respectively at 112 ppm of alum. After irradiation, it is observed that absorbance decreased rapidly at 540 nm by increasing the radiation dose because of macromolecules degradation and then it decreased slowly to a degree of decoloration of 95% at 3 kGy. The level of pH decreased by irradiation and then changed very slowly or remained constant with increasing irradiation dose. Conclusion: The results indicate that a combination of coagulation/ flocculation and irradiation is so effective for turbidity removal and decoloration. Coagulation process eliminates suspended particles from disperse dyes effectively, while destruction of soluble dye molecules happens by irradiation, which considerably increases decoloration efficiency.