Application of vacuum membrane distillation for small scale drinking water production

Publication Type:
Journal Article
Citation:
Desalination, 2014, 354 pp. 53 - 61
Issue Date:
2014-12-01
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© 2014 Elsevier B.V. This study evaluated the applicability of a modified design vacuum enhanced-multi effect membrane distillation (V-MEMD) for drinking water production with feed solution containing NaCl and CaSO 4 . The applicability was studied in terms of flux, scale formation and ease of cleaning. A slight flux decline (18-20%) was observed with loosely deposited crystals in the membrane module during the 920min of the operation. Larger formation of crystal (volume weighted mean size, D[4,3]) was observed in the final feed brine (D[4,3] brine feed =455.96μm) compared to that inside the module (D[4,3] brine module =62.68μm). The loose crystal deposition was attributed to the absence of hydraulic pressure, low feed temperature, high turbulence (Re=5665.6) and short membrane retention time (21.6s). The crystal formation in the membrane module, D[4,3] brine module increased with reduced permeate side vacuum and lower feed velocity. Periodic DI water flushing wa s found to be efficient to remove the scaling. The feed component mass balance showed that most of the components were able to be removed with 2L DI water flushing. A 70% recovery ratio was projected for a scaled-up unit, highlighting the suitability of the V-MEMD as a small scale system for drinking water production.
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