Mechanism of bacterial and viral transport through microfiltration membranes

Microorganisms such as Q beta, MS2, T4 virus and several bacteria strains in Pseudomonas, Alcaligenes and E-coli groups were filtered with different pore size: nuclepore and anopore flat sheet membranes in dead end mode. The obtained rejection results were analyzed with existing pore models in which the rejection is related to the ratio of solute size to pore size. The existing Pore models (transport equations) were adjusted to accommodate the microfiltration range particles. The adjusted pore models showed good agreement with the obtained experimental rejection results for virus while the bacteria rejection results showed a deviation. This deviation is partially explained with the wide size distribution of bacteria. The equivalent spherical diameter can be used to represent the virus size while the oval diameter of the cells may be the best possible dimension for bacteria size in membrane filtration. This determination showed the possibility of bacteria cells approaching the membrane pores in their longitudinal direction. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.