When the PVDF–PVP membranes were used to treat oily waste
water, their separation performance was improved greatly compared
with that of the PVDF membranes. Besides, fouling mechanism
was studied and it could be found that external fouling was
the main cause of flux decline. Moreover, flux recovery of the
fouled PVDF–PVP membranes after cleaned using 3 wt.% NaOH
aqueous solution exceeded 90% and was much superior to that of
the fouled PVDF membranes.