Journal of Membrane Science, Vol.514, 636-645, 2016
Evaluating ionic organic draw solutes in osmotic membrane bioreactors for water reuse
The performance of two ionic organic draw solutes, namely sodium acetate (NaOAc) and ethylene-diamine-tetra acetic acid disodium salt (EDTA-2Na), during osmotic membrane bioreactor (OMBR) operation was investigated in this study. Their performance was compared to that of sodium chloride (NaCI). A reverse osmosis (RO) process was integrated with OMBR to form an OMBR-RO hybrid system for draw solute recovery and clean water production. Results show that the NaOAc and EDTA-2Na draw solutes significantly reduced salinity build-up in the bioreactor in comparison with NaCI during OMBR operation. At the same osmotic pressure, these two ionic organic draw solutions produced slightly lower water flux, but considerably less reverse salt flux than NaCI. Compared to NaCI and NaOAc, EDTA-2Na resulted in significantly less fouling to the forward osmosis membrane. Regardless of the draw solutes, the OMBR-RO hybrid system could remove all 31 trace organic contaminants investigated in this study by more than 97%. Results reported here suggest that ionic organic draw solutes can be used to mitigate salinity buildup in the bioreactor during OMBR operation. Crown Copyright (C) 2016 Published by Elsevier B.V. All rights reserved.
Keywords:Osmotic membrane bioreactor (OMBR);Organic draw solute;Salinity build-up;Reverse osmosis (RO);Trace organic contaminants (TrOCs)