Permeate flux in crossflow ultrafiltration under intermediate pressures

The intermediate pressure range stands for an important condition for ultra filtration operations where permeate flux falls below that predicted from a linear flux-pressure relationship but does not reach the limiting flux. Op timal performance of ultrafiltration might be achieved on the upper end of the intermediate pressure range because the maximum permeate flux will be o btained at the lowest possible pressure. Unlike in the low pressure range o r in the high pressure range, little has been known about the behavior of p ermeate flux in the intermediate pressure range. A general theory of permea te flux in the intermediate pressure range is developed in this study. The theory includes the linear-increasing and limiting fluxes as two special ca ses and, therefore, can be used to study the behavior of permeate flux in u ltrafiltration in the whole pressure range. (C) 1999 Academic Press.