▎ 摘　　要

It is important to reduce the turbidity of drinking water to the level specified in the standards. Herein, conventional and modified coagulation-flocculation processes were applied to remove turbidity from drinking water. At first, the response surface methodology was utilized to design experiments, evaluate the effect of independent variables, and optimize the conventional coagulation process. According to the results of the analysis of variance, the maximum turbidity reduction of 95.7% was obtained under the optimal pH value of 6.9, FeCl3 dosage of 48 mg/L, and mixing time of 46 s in the rapid mixing unit. After determining the optimal conditions of the conventional coagulation-flocculation process (CFP), to reduce the amount of turbidity according to the existing standards (5 NTU) for drinking water, the modified CFP with graphene oxide (GO) and magnetic (Fe3O4) nanoparticles was used. The highest efficiency of turbidity removal (97.6%) was achieved when a combination of GO and Fe3O4 was used, resulting in meeting the standard level of turbidity. On the other hand, the settling time was significantly reduced.