Study on the performance of PVDF membranes and its degerming effect for application of draft beer filtration

Hydrophilic Poly ( vinylidene fluoride) ( PVDF) microfiltration membranes with finger- like structure and reticular structure were used to filter bacteria. The relationship between the structure and pore size of PVDF membranes and its degerming effect was studied.The influence of membrane structure and clean manner on the degerming effect and filtration flux during draft beer filtration was also investigated.Scanning electron microscope ( SEM) and water contact angle measurer were used to characterize the membrane structure and its hydrophilicity.The results showed that the degerming effect could meet the requirement of draft beer when the pore size grade of PVDF membrane was about 0.22μm for both finger-like structure and reticular structure membranes.There were no significant differences between base- water- acid- water cleaning manner and the water cleaning manner on the recovery of the filtration flux of reticular structure membranes.The draft beer flux for both of the cleaning ways was stable to 22.2 ~ 22.4L / ( m2·h) around. The base- water- acid- water cleaning method was beneficial to the performance of finger-like membranes where the draft beer flux was stable to 40.8L / ( m2·h) .Compared to the base-water-acid- water cleaning way, the draft beer flux was stable to 35.0L / ( m2·h) when the water cleaning method was used. The results indicated that the water cleaning method was available for draft beer filtration degerming when hydrophilic PVDF microfiltration membranes were used in performance.