s Sadeghi - MSc student, Civil and Environmental Engineering Department, Amirkabir University of Technology (AUT),
M.R. Alavi Moghaddam - Associate Professor, Civil and Environmental Engineering Department, Amirkabir University of Technology (AUT), Hafez St. Tehran ۱۵۸۷۵- ۴۴۱۳, Iran
M. Arami - Professor, Textile Engineering Department, Amirkabir University of Technology (AUT), Hafez St.Tehran ۱۵۸۷۵- ۴۴۱۳, Iran

The coagulation/flocculation process is well known as one of the most efficient physico-chemical methods for removal of heavy metals from industrial wastewaters. In this study, the main aim is to investigate the performance of coagulation/flocculation process on removal of hexavalent chromium using polyaluminum chloride. For this purpose, the effect of different parameters such as pH, polyaluminum chloride dosage and initial chromium concentration on removal efficiency were examined. The obtained results showed that the removal of chromium was definitely dependent on the pH variations. At the optimum pH (6), maximum removal efficiencies above 90% were obtained in different initial chromium concentrations of 50-500 mg/L with different dosages of polyaluminum chloride. Also, the obtained results showed that by increasing the initial concentration of chromium from 50 to 500 mg/L, Q (the amount of the removed hexavalent chromium per unit mass of polyaluminum chloride) has increased from 0.019 to 0.057

Coagulation/flocculation, Hexavalent chromium removal, Coagulants, Polyaluminum chloride