Effect of Praestol as a Coagulant-Aid to Improve Coagulation-Flocculation in Dye containing Wastewaters

This study was conducted to investigate the effect of praestol, as a coagulant-aid, to improve coagulation-flocculation process in the removal of disperse red 60 from aqueous solutions. The effect of various parameters including coagulants dose (10-1000 mg l^-1), praestol dose (0-1000 mg l^-1), solution pH (3-11), initial dye concentration (100-500 mg l^-1), flocculation speed (30-60 rpm), flocculation time (15-30 min), settling time (5-60 min) and ionic strength (0-6 mg l^-1) was evaluated on the dye removal. The dye removal efficiency was substantially increased by using praestol in the concentration of 80 mg l^-1 and 400 mg l^-1 for coagulation with alum and polyaluminum chloride (PACl), respectively. The maximum dye removal by alum coupled with praestol (Al-P) and PACl coupled with praestol (PA-P) was found to be 97.8% and 98.7%, respectively that were occurred at pH 7. The results showed that the application of PA-P or Al-P can be effectively used to remove disperse red 60 (DR 60) in aqueous solutions.