Supercritical carbon dioxide fluid cleaning of extracellular polymeric substance surrogates on seawater reverse osmosis membranes

Abstract

Fouling of seawater reverse osmosis (SWRO) membranes cause of reduced water flux and increased energy usage, which requires frequent cleaning to maintain performance. We demonstrate Supercritical carbon dioxide (sCO2) fluid, as an alternative membrane cleaning reagent, can effectively remove extracellular polymeric substances (EPS) that form on SWRO membranes. Carbon dioxide (CO2) gas was turned into sCO2 fluid by elevating the pressure (to 7.5 MPa) and temperature (to 35 °C). The SWRO membrane coupons were fouled by EPS surrogate materials (sodium alginate or bovine serum albumin), and the sCO2 cleaning was conducted to recover the deteriorated water permeation flux. We present that the sCO2 cleaning can effectively eliminate the EPS surrogate materials from the membrane surface with a great cleaning efficiency (75–90 %). In addition, it was observed that sCO2 cleaning does not alter the properties (i.e., surface functional groups and salt-rejecting performance) of polyamide-based SWRO. Our findings suggest that sCO2 is applicable to remove EPS surrogate materials from the membrane.