Symposium 7 : Invited Speaker 

Advances in membrane technology: forward osmosis/ pressure retarded osmosis membranes and biomimetic membranes

Assoc. Prof. Rong Wang
Nanyang Technological University (NTU), Singapore

Abstract

Forward osmosis (FO) process has gained much attention recently because of its potential to either reduce energy consumption (in seawater desalination) or produce energy (pressure retarded osmosis (PRO)). However, the viability of FO/PRO technology for large-scale implementation has been impeded by two main technical challenges:  (1) the identification of a suitable draw solution which is able to generate a high osmotic pressure and is readily regenerated; and (2) the lack of appropriate membranes for FO/PRO application that can produce a reasonably high flux and withstand certain pressure. We are developing novel FO/PRO membranes based on interfacial polymerization in both hollow fibre and flat sheet format. Optimization of FO/PRO membrane structure has produced membranes with very high performance, for example fluxes > 40 L/m²hr with a draw solute of 0.5M NaCl, and strong mechanical strength (9 bar).  A power density as high as 10.6 W/m² can be achieved using seawater brine (1.0M NaCl) and wastewater brine (40mM NaCl), which is twice of the goal of 5 W/m² required to make the PRO commercially viable. This presentation will review the research development in FO/PRO membranes at the Singapore Membrane Technology Centre.

In addition, there is an increasing interest in mimicking the natural cellular membranes by incorporating water channel proteins- aquaporins (AQPs) into various polymeric membrane matrixes for water filtration applications in recent years. It has been recognized that the integration of protein embedded vesicles/films and the substrate is the one of the most challenging tasks for the preparation of AQPs based biomimetic membranes.   This presentation will also highlight the R&D activities in this area carried out at the Singapore Membrane Technology Centre.