Received: 11 April 2019 Accepted: 13 May 2019 Published: 01 June 2019
Flocculation is an important industrial process for solid-liquid separation during the primary purification of wastewater. Effects of the solution pH and flocculants dosage to examine the performance of five commercially available cationic & anionic polyacrylamides (Chemfloc 3876, Chemfloc 1510C, Chemfloc 530A, AN913 and AN913 SH), with different molecular weights and different charge densities to treating the tile factories wastewater were investigated. To minimize turbidity and total suspended solids (TSS), the experiments were carried out using jar tests, and response surface methodology (RSM) was applied to optimize this process. The optimal conditions for flocculent dosage and pH were determined 20 mg/l and 3-5.25, respectively, where 99.6% of TSS removal and final turbidity of 18 NTU could be obtained for Chemfloc 1510C. This paper shows that higher molecular weight polymers improved initial aggregation but the effect of cationic charge was more important for a stable flocculation. The results suggest that single-polymer system can be used alone in the coagulation-flocculation process due to the efficiency of the polyacrylamide.