The influence of temperature on dynamic membrane structure

Abstract

This study investigates the influences of cold source-water temperatures and warm temperature recoveries on the dynamic changes of membrane structure. The morphology of membrane pores on the membrane surface was firstly compared through SEM images. The visual comparisons of the images show that the shrinkage of membrane pores occurred in the cold-water (0.3, 5, 10°C) treatments and could then be recovered in the warm-water (room temperature and 35°C) remediation. Furthermore, the dynamic changes in membrane pore sizes during cold temperature and recovery treatments were illustrated by the percentile membrane diameters — d10, d50 and d90. The membrane pore sizes in cold-water treatment at 0.3°C shrank faster and were smaller than those of 5 and 10°C. The recovery treatment at 35°C, which fully recovered the membrane pore sizes to those of virgin membrane, was much more effective than room temperature treatment. Room temperature recovery only restored the membrane pores close but not exceeding the original sizes under tested conditions. Both cold temperature treatments and warm water recoveries stabilized the membrane pore sizes after around 24 hours. Finally, membrane structure changes over time have been modelled. It implied that warm water cleaning could retrieve the membrane structure losses affected by cold source water.