EFFECTS OF PORE-SIZE ON SEPARATION MECHANISMS OF MICROFILTRATION OF OILY WATER, USING POROUS-GLASS TUBULAR MEMBRANE

The effects of the average pore size in porous glass tube membranes on the performance of the cross-flow microfiltration were investigated u sing oil-in-water emulsion. The flux decline with filtration time was divided into two stages. The filtration mechanism in the first stage c an be explained by three types of blocking filtration models such as t he complete type for pore size 0.27 mu m membrane, the intermediate ty pe for pore size 0.75 mu m membrane and the standard type for pore siz e 1.47 mu m. The second stage can be also explained by the cake filtra tion model. The oil rejection is found to decrease with time initially , but is soon stabilized at a constant level. This was explained by th e comparison among the average pore size, the pore size distribution o f used membrane and the droplet distribution of the feed emulsion. The surfactant transmission of the cake filtration stage was 49% for 0.27 mu m membrane, 80% for 0.75 mu m membrane and 99% for 1.47 mu m membr ane. (C) 1998 Elsevier Science B.V.