AWWA MTC61239

The objective of this project was to demonstrate changes in performance characteristics of microfiltration (MF) membranes by uni-axial stretching, and to predict the change in the aspect ratio (ratio of the lengths of the major and minor axes) of pore entrances from known membrane properties and stretching conditions. The ultimate goal of this research is to develop a fundamental understanding of the materials science of membrane stretching. The study will ultimately determine how the membrane material, initial membrane pore structure, and stretching conditions (rate, ultimate stretch percent, and temperature) influence the final membrane structure. If successful, the study will develop a simulation package that would provide membrane manufacturers with a tool that could be used to tailor membranes via stretching. The more immediate task has been to conduct permeation and particle challenge studies as a way of monitoring the impact of stretching on membrane performance. Implicit in this work is the suggestion that it is possible to improve membrane performance for water treatment by controlling the characteristics of pores on the membrane surface. The experimental procedure used a biaxial stretcher and two dead-end permeation modules were used for permeation experiments. Particulate challenge experiments were performed with two types of particles that included Min-u-sil 5, an irregularly shaped particle that is 99.2% silicon dioxide, and Min-u-sil 30 used to test the 10 µm pore size membrane. Min-u-sil 30 is the same material as Min-u-sil 5 described above, but with larger particles and an even broader size distribution. Includes table, figures.