Microalgae (Scenedesmus obliquus) dewatering using forward osmosis membrane: Influence of draw solution chemistry

Larronde-Larretche, M. and Jin, X. (2016) Microalgae (Scenedesmus obliquus) dewatering using forward osmosis membrane: Influence of draw solution chemistry. Algal Research, 15, pp. 1-8. (doi: 10.1016/j.algal.2016.01.014)

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Forward osmosis (FO) is gaining increasing interests for its potential applications in biofuel generation. In this study, bench-scale experiments were conducted to investigate the FO performance for microalgae dewatering which is one of the technical challenges in algal biofuel production. The filtration performance was assessed by analyzing permeate water flux and algal biomass concentration in the feed solution. Compared to the active layer facing draw solution (AL-DS) orientation (> 45% flux reduction), active layer facing feed solution (AL-FS) was more efficient (< 15% flux reduction) due to the lower membrane fouling and higher cleaning efficiency (> 90% water flux recovery after deionized water flushing). In the AL-FS orientation, FO performance strongly depended on the draw solution chemistry with NaCl exhibiting the best results. When Ca2 +-containing solution was used as draw solution, microalgae responded to the back diffusion of calcium ions by an extensive excretion of carbohydrates, accelerating the formation of algal flocs, thus enhancing the rate and extent of flux decline and reducing the algae dewatering efficiency. However, most of the flux decline was reversible by simple hydraulic flushing without any chemical cleaning reagents and air scouring. In addition, substantial adsorption of algal biomass was observed on feed spacer. This study has the implication for Scenedesmus obliquus dewatering using FO technology. Selection of AL-FS orientation, Ca2 +-free draw solutions and prevention of microalgae adhesion onto feed spacer may significantly improve the efficiency and productivity of the dewatering process.

Item Type:Articles
Additional Information:This work was supported by School of Engineering, University of Glasgow. The first author was supported by James Watt Scholarships. These financial supports are gratefully acknowledged.
Glasgow Author(s) Enlighten ID:Jin, Dr Xue and Larronde-larretche, Mathieu
Authors: Larronde-Larretche, M., and Jin, X.
College/School:College of Science and Engineering > School of Engineering > Infrastructure and Environment
Journal Name:Algal Research
ISSN (Online):2211-9264
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Algal Research 15:1-8
Publisher Policy:Reproduced under a Creative Commons License

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