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Membrane scaling during seawater desalination by direct contact membrane distillation

The results reported in this study demonstrate the viability of DCMD for small-scale seawater desalination in Vietnam given its long coastline together with a large number of islands and great solar energy availability. | Vietnam Journal of Chemistry, International Edition, 54(6): 752-759, 2016 DOI: 10.15625/0866-7144.2016-00399 Membrane scaling during seawater desalination by direct contact membrane distillation Duong Cong Hung1, Pham Manh Thao2*, Luong Trung Son2, Huynh Thai Nguyen2, Nghiem Duc Long1 1 Strategic Water Infrastructure Laboratory, School of Civil Mining and Environmental Engineering, University of Wollongong, Wollongong, NSW 2522, Australia 2 School of Environmental Engineering, Faculty of Physics and Chemical Engineering Le Quy Don Technical University Received 2 September 2016; Accepted for publication 19 December 2016 Abstract Seawater desalination by membrane distillation (MD) has great potential for fresh water provision in small and remote areas. Amongst four basic MD configurations, direct contact membrane distillation (DCMD) has a simple arrangement; thus, it is most suited for small-scale seawater desalination application. In this study, membrane scaling during a seawater DCMD desalination process was systematically investigated. Mass transfer coefficient of the DCMD system was first determined with Milli-Q water. The obtained mass transfer coefficient was used to simulate the influence of feed salinity increase and membrane scaling on water flux. The simulation results were then validated by experimental data. Results reported here demonstrate a notable influence of feed salinity increase and membrane scaling on water flux, particularly at a high water recovery. The rapid increased feed salinity during the concentration of seawater at water recoveries above 50 % magnified both temperature and concentration polarization effects, thus reducing the experimentally measured water flux compared to the calculated one. In addition, membrane scaling caused by the precipitation of CaSO4 and MgSO4 at high water recoveries further reduced the measured water flux. Moreover, feed operating temperature had a profound effect on both water flux and membrane scaling. .