Vacuum membrane distillation for deep seawater: experiments and theory

Abstract

This paper investigates the feasibility and potential of vacuum membrane distillation (VMD) for concentrating deep seawater (DSW) of 34 g/kg and its reverse osmosis (RO) brine of 62 g/kg. In this work, a small pilot-scale VMD system was developed and distillate fluxes were measured for feed solutions of de-ionized water (DIW), DSW and RO brine DIW provided the highest distillate flux followed by DSW and RO brine, but effects of feed salinity on the flux is not remarkable. A simple analysis was performed using conventional mass transfer theory, which provides good qualitative understanding of relative fluxes of DSWs normalized by that of DIW. The experimental observation indicated that VMD can be readily used for desalination and concentration of salinity solutions as high as 62 g/kg. This supports great potential of VMD for membrane crystallization of precious DSW minerals.