The constant-rate operation of a system utilizing asbestos filter-pads for the cold sterilization of a tissue culture medium is described. Filtration theory is briefly reviewed with regard to the constant-rate process, and the results of several data treatment methods are reported. The standard law of Hermans and Bredke49 5 best describes the constant-rate data. Computation of the data, when plotted by the standard-law method, results in two straight lines divided by a transition zone. The second region is characterized by a slower plugging rate and a plot of the standard-law slopes versus the initial filtration pressures shows a linear relation. The constant-rate method is compared with the constant-pressure method and is found to yield equivalent overall filtrate rates at lower operating pressures.
The observed filtration behaviour is discussed, and available data are presented to indicate the sterilization capability of the filter. * This paper was presented before the ACS meeting held in New York, Sept-139 * Republic Seitz Filter Corp., Newark, N.J.
* These particular through-puts do not reflect any experimentally determined maximum through-puts before a breakthrough of contaminants may occur.