Evapoporometry determination of pore-size distribution and pore fouling of hollow fiber membranes

Pore-size distribution determined by evapoporometry of unfouled (dark-shaded) and fouled (light-shaded) polyvinylidine fluoride (PVDF) hollow fiber membranes; fouling involved a constant flux of 70 l/m2 h, concentration of l.0 g/l of bentonite and 20 mg/l of humic acid, and employed a cycle consisting of 15 min of filtration followed by 2 min of backwashing during which the aeration rate was 0.0011 m/s; fouled membranes were observed after the 9th cycle; fouling is seen to cause a marked shift in the pore-size distribution towards smaller pores and a decrease in the average pore diameter from 34.6 nm to 22.5 nm owing to internal pore fouling. 128