RESEARCH ARTICLE


Optimization of Operating Conditions in Forward Osmosis for Osmotic Membrane Bioreactor



Jian-Jun Qin*, 1, Maung Htun Oo1, Guihe Tao1, E. R. Cornelissen2, C. J. Ruiken3, K. F. de Korte3, L. P. Wessels2, Kiran A. Kekre1
1 The Centre for Advanced Water Technology, PUB Consultants Pte Ltd, 80/82 Toh Guan Road East, #C4-03, 608575, Singapore
2 Kiwa Water Research, P.O. Box 1072, 3430 BB Nieuwegein, the Netherlands
3 Waternet, Spaklerweg 16, 1096 BA, Amsterdam, The Netherlands


© 2009 Qin et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Centre for Advanced Water Technology, PUB Consultants Pte Ltd, 80/82 TOH Guan Road East, #C4- 03, Singapore 608575; Tel: +65-63262914; Fax: +65-63262929; E-mail: QIN_Jianjun@pub.gov.sg


Abstract

Objective of this study was to conduct a baseline study of osmotic membrane bioreactor (OMBR) - optimization of operating conditions in forward osmosis (FO). Experiments were conducted with an FO pilot system. Tap water was used as the feed and NaCl and MgSO4 solutions were used as draw solution. Effects of various operating conditions on flux have been investigated. In addition, pure water permeability of the FO membrane was tested. It was observed that the plant operation could be stablized within 1 h. When the membrane selective layer faced to the feed, a flux of 6.3 lm-2h-1 (LMH) was achieved at 24 atm osmotic pressure and 25 °C and effects of feed velocity and air velocity on flux were not siganificant under the testing conditions due to low external concentration polarization (ECP). However, when the selective layer faced to the draw solution, the flux was enhanced by 64% due to much reduced internal concentration polarization (ICP), the flux sharply increased with an increase in velocity of the draw solution in the laminar flow pattern range due to a countable effect of dilutive external concentration polarization (DECP) and leveled off after the flow pattern became turbulent. NaCl performed much higher efficiency than MgSO4 as an osmotic agent due to a greater solute diffusion coefficient of NaCl.

Keywords: Draw solution, forward osmosis, osmotic membrane bioreactor, osmotic pressure.