UQ eSpace

Abstract

Reverse osmosis (RO) is a worldwide applied technology (as per International Water Association, >11,000 plants as of 2015) for water desalination which facilitates salt rejection by using an applied pressure on feed side (Liu and Chen 2013). Low energy consumption and simplicity in design distinguishes RO from other separation process such as thermal distillation, vapour compression distillation and multistage flash distillation (Otitoju, Saari et al. 2018). Membrane functionality is typically associated with the level of ageing, thickness, surface roughness, density of defects and chemical structure. In this project, commercially available thin film composite BW30 RO membranes were tested before and after laser impairment with the aim of assessing their performance. The highest water and saline flux were obtained for the membrane impaired with 90 holes at a laser pulse density of 20p/m 2 , penetrating through all the composite layers. However, the flux values subsequently varied with the change in pulse density and number of holes. Although fluxes varied with the level of impairment, salt rejection data for all the experiments stayed above 99%, suggesting that the rejection is maintained despite damage. This study successfully shows that membranes can be impaired in a controlled manner and that all tested membranes, despite losing the barrier layer, kept almost intact their salt rejection abilities. This work establishes a good methodology to produce samples for future membrane impairment testing, with great application potential in validating virus and/or micropollutants removal.