Microalgal biomass dewatering using forward osmosis membrane: influence of microalgae species and carbohydrates composition

Larronde-Larretche, M. and Jin, X. (2017) Microalgal biomass dewatering using forward osmosis membrane: influence of microalgae species and carbohydrates composition. Algal Research, 23, pp. 12-19. (doi:10.1016/j.algal.2016.12.020)

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Abstract

The potential application of forward osmosis (FO) in microalgae dewatering requires an improved understanding of the factors that control membrane fouling which can reduce dewatering performance in terms of water flux through membrane and algae recovery. The aim of this study was to elucidate the influence of algae cell wall carbohydrate composition on the FO dewatering performance using three types of draw solutions (sea salts, MgCl2 and CaCl2). Experimental results suggest that the interaction between microalgae and back diffused draw solutes plays a key role. Scenedesmus obliquus with fructose and abundant glucose and mannose in its cell wall showed strong response to the back diffusion of calcium ions which encouraged S. obliquus to produce more extracellular carbohydrates and formed a stable gel network between algal biomass and extracellular carbohydrates, leading to algae aggregation and severe loss in both water flux and algae biomass during FO dewatering with Ca2 +-containing draw solution. Chlamydomonas reinhardtii without fructose but great galactose showed a similar response to the calcium back diffusion but to a lower extent. Both S. obliquus and C. reinhardtii did not cause obvious membrane fouling but dramatic algae biomass loss at the end of FO filtration with MgCl2 draw solution due to their interaction with back diffused Mg2 + ions which led to the deposition of algae flocs onto membrane surface and/or feed spacer. Chlorella vulgaris without fructose was the most suitable microalgae species to be dewatered by FO with algae recovery over 81% and negligible flux decline regardless of which draw solution was applied. The findings improve mechanical understanding of FO membrane fouling by microalgae; have significant implications for the algae species selection; and are critical for the development and optimization of FO dewatering processes.

Item Type:Articles
Status:Published
Refereed:Yes
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
Publisher:Elsevier
ISSN:2211-9264
ISSN (Online):2211-9264
Published Online:12 January 2017
Copyright Holders:Copyright © 2016 Elsevier B.V.

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
734371Novel osmotic membrane photobioreactor for suitable wastewater treatment and biofuel productionXue JinCarnegie Trust for the Universities of Scotland (CARNEGIE)70440ENG - ENGINEERING INFRASTRUCTURE & ENVIR