On the effect of specific boundary flux parameters on membrane process design

The boundary flux concept permits to describe the fouling behaviour of membrane systems as a function of the operating time. The method relies on a set of equations that is possible to integrate in time, thus permitting to evaluate the separation process outcome and performances. This study focuses on the relationship between the membrane area requirements and specific parameters of the boundary flux concept on different membrane systems characterized by different waste feed streams and operating conditions. The target of the analysis was to identify which parameters of the boundary flux equations are the most influent one on the membrane area requirements. The knowledge of the relevant parameters can strongly assist membrane process designers to minimize the capex of the developed plants. The study was performed on many different systems, available in literature, and at different operating conditions. The adopted procedure was as follows: 1. in a first step, by using infinite membrane area, the maximum recovery value Ymax of a specific membrane separation process was determined. 2. afterwards, the separation target was equally fixed at volume unity of feed (1 m3) produced during time unity (1 h) at three different recovery values, that is Y equal to 50% Ymax, 75% Ymax and 90% Ymax, respectively. The required membrane area below boundary conditions and no irreversible fouling formation was calculated by means of the simulation code, using a Newtonian trial&error procedure.