Predicted performance profiles along a long-tube cross-flow microfiltration system

• Published in: Desalination 1989, Vol.71 (3), p.247-264
• Main Authors: Pillay, V.L., Brouckaert, C.J., Buckley, C.A., Raal, J.D.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; General treatment and storage processes; Pollution; Wastes
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/0011-9164(89)85027-1

In cross-flow microfiltration (CFMF) tubes where a significant change in pressure, concentration and flow rate occurs along the tube, the cake thickness and permeate flux may also change along the length of the tube. In this paper, an attempt is made to ascertain the trends that cake thickness and permeate flux are likely to exhibit in a long tube, based on the integration of the Hunt model for short tube elements. Seemingly anomalous results are explained and validated in terms of a generalised phenomenological model for CFMF. It is found that the cake thickness can increase or decrease along the tube, depending on the inlet conditions to the system. In principle, it is feasible to choose operating conditions that would result in a constant cake thickness along the tube, thereby avoiding the probability of tube blockage or changing permeate quality. The average flux for a tube is considerably lower than the point flux at the inlet end of the tube. Thus any attempt to calculate the permeate production rate by using only the inlet operation conditions is likely to lead to an error in design.