Studies on the scale-up of microfiltration membrane devices.

This paper addresses the prediction and modeling of fouling in microfiltration (MF) membrane devices during the filtration of biological solutions. The membrane-fouling model described can be used by bioengineers to characterize a solution's filterability when using a specific microfiltration product line. This allows bioengineers to predict the scale up of filtration from laboratory through clinical production to full marketing production. The model used to correlate filtration results contains two parameters (initial flux and membrane plugging constant) that must be determined experimentally. Once these parameters are known, it is possible to predict the performance (fouling and throughput) of larger membrane devices as a function of operating pressure, processing time, and membrane area. This allows users of MF devices to perform laboratory tests of their solution at relatively small scale, and based on these tests determine the performance of larger-scale MF devices for filtration of the same solution.

A membrane-based method for removal of toxic ammonia from mammalian-cell culture.

Many mammalian cells grown in culture excrete ammonia, which, when it accumulates, limits cell growth and reduces product synthesis. Common tactics for minimizing the effects of ammonia accumulation are uneconomical, requiring large quantities of media and incurring high capital costs. Solution-diffusion membranes were investigated for ammonia removal, and a supported-gas membrane was identified that could be used to remove ammonia rapidly to well below inhibitory levels. Medium treated using this membrane was reused to culture baby-hamster kidney cells, resulting in a cell growth rate that was essentially the same as that for cells grown in fresh medium.