Removal of Remazol red RB by using AI (III) as coagulant-flocculant: Effect of some variables on settling velocity

This study addresses the research of the removal of a textile dye from aqueous solutions by using aluminum ions as coagulant-flocculant. A simulated textile wastewater was prepared from Remazol Red RB textile dye. The purpose of this study was to investigate the effects of temperature, pH, and concentrations of the cationic surfactant and electrolyte concentration on the settling velocity of the simulated textile wastewater. While investigating these factors, levels of variables were determined by considering the characteristics of traditional textile wastewater like pH, temperature, and dye concentration. Although traditional coagulation-flocculation processes make use of different aluminium salts as coagulant-flocculent, in this study, Al ions dissolved in pH and temperature of traditional textile wastewater were used. Furthermore, sludge volume index values (SVI) were determined and conductivity measurements carried out. The results showed that, in the working range of these variables, the spectroscopic color measurement revealed 100% decolorization yield of wastewater. In conclusion, researchers found that the optimum settling velocity conditions were as follows: low temperature (273K), surfactant concentration of 0.10 g L-1, electrolyte concentration of 0.10 g L-1, dye concentration of 0.025 g L-1 and a pH of 10.05. Finally, by conducting experiments twice under the obtained optimum values, mean settling velocity was 0.014 m min-1 and the mean sludge volume index 140 mL g-1.