[RoTrac capillary pore membranes for laboratory filtration. I. Degermination filtration]

RoTrac capillary pore membranes (CPM) are produced by means of the nuclear track technology. Thus a defined and in wide ranges independent adjunction of the different membrane parameters (diameter, density, shape and inclination of pores) is possible. The wanted uniform separation diameter of the membrane can exactly be chosen according to the size of the microorganisms to be rejected. By dead end filtration experiments with E. coli and Serratia marcescens the suitability of RoTrac-CPM in bacteria removal filtration was proven. Blocking was very strong for membranes with pore diameters in size range of the microorganisms (approximately 0.45 micron). Though the filtrate had immense reduced bacteria counts (from 10(7)-10(8) to 10-100 bacteria/ml), it was generally not sterile. For membranes with a pore diameter of 0.2 micron and smaller blocking was essentially lesser. Here filtrate was always sterile. Flux (and thus the filterable volume) corresponds to values of competitive membranes. Compared with those the proven possibility of simple cleaning is an advantage, because rejection and blocking of symmetrical CPM occur directly on the membrane surface. This is promising for use of CPM in cross flow filtration.