Fig. 3(d) shows the effect of VRF on the membrane fouling. The
highest S/N ratio was determined at VRF 4. S/N ratio was decreased
with decreasing VRF value. Hence, flux decline caused by fouling
was lower at VRF 4.This case can be explained by assuming that a cake layer formation due to the adsorption of more pollutant to the
membrane surface at higher VRF value. This cake layer behaved as a secondary membrane, which prevented the penetration of pollutants causing lower membrane fouling