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

Textile wastewaters from dyeing and finishing processes are heavily polluted with dyes, textile auxiliaries 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 wastewater samples were investigated by combined process of coagulation/ flocculation and electron beam irradiation. The experiments have been done on model dye solution samples which prepared from ten dyes that are supplied from Yazd Baff textile factory. Aluminum sulphate was employed to determine the optimum conditions for removal of turbidity by jar-test experiments. Then samples were irradiated by 10 MeV electron beam of Rhodotron TT200 accelerator at different doses of 1, 3 and 6 kGy. Absorption spectra of the samples were measured using UV-Vis spectrophotometer (Perkin Elmer, Lambda 25). The pH and turbidity values of the solutions were measured by a Metrohm 827 model pH meter and 2100AN turbidimeter (Hach company). According to results, the degree of decoloration and turbidity removal of synthetic dye solutions increased dramatically when the alum concentration increased and reached to 64% and 90% respectively at 112 ppm. After irradiation, it is observed that absorbance at 540 nm decreased rapidly by increasing of radiation dose, because of macromolecules degradation and then decreased slowly and degree of decoloration reached to 95%. The amount of pH was decreased by irradiation and then changed very slowly or remained constant with increasing irradiation dose. The above results indicate that combination of coagulation/ flocculation and irradiation of 10 MeV electron beam is so effective for turbidity removal and decoloration. Coagulation process eliminates suspended particles from disperse dyes effectively, while destruction of soluble dye molecules happen by irradiation that increase decoloration efficiency considerably.