Automated Hollow Fiber Ultrafiltration: Pyrogen Removal and Phage Recovery from Water

Abstract

The operational aspects of automated hollow fiber ultrafiltration systems are reviewed both with respect to filtrate utilization as well as a recovery system for membrane-retained species. Typifying the former is the removal of pyrogens, while an example of the latter is the removal and subsequent recovery of f2 bacteriophage from both tap and lake water. While preparation of colloid-free filtrate can be easily explained by sieving governed by the pore size of the membrane, the recovery of retained species necessitates a more complex model. With respect to phage, logarithmically decreasing concentrations of phage are recovered in the concentrate solution by successive backflushes of the membrane with filtrate. A model is proposed to explain the logarithmic decrease in concentration as a function of the backflush flux and volumetric throughput. The model can be used to predict the total number of original phage in a water sample filtered through the unit on the basis of an assay of the phage in a single backflush. Phage was selected as a model system to establish operational parameters for extending these studies to encompass enteroviruses in water.