Factorial design applied to flux decline of anionic polyacrylamide removal from water by modified polyvinylidene fluoride ultrafiltration membranes

Abstract Experiments were performed with a lab-scale setup under constant flux conditions with synthetic feed water containing anionic polyacrylamide (APAM) colloid as a fouling component to predict the decline of UF process. A four-factor two-level full factorial design analysis was conducted to screen the significant factors influencing relative flux reduction ( J / J 0 ) of APAM with 6880 kDa in ultrafiltration (UF) process. Factors investigated were pH of the solution (3 ~ 10), total dissolved solids (TDS) (0 ~ 3.5 g/L), concentrations of APAM (10 ~ 100 mg/L), and transmembrane pressures (TMP) (0.07 ~ 0.2 MPa). A significant TMP effect on J / J 0 of this APAM UF process was obtained. Analysis of variance (ANOVA) showed a high coefficient of determination value ( R 2  = 0.9658) and satisfactory prediction regression model was derived. The optimum UF TMP, pH and initial concentration of solution were found to be 0.07 MPa, 3, and 10 mg/L, respectively. Under the optimal value of process parameters, J / J 0 (24.9%) was obtained for this UF process after 30 min.