Scale formation is inevitable problem when seawater is treated by vacuum membrane distillation. The reason is the high concentration of calcium ion(Ca2+), sulfate ion(SO4 2-) and bicarbonate ion(HCO3 -). These ions form calcium sulfate(CaSO4) and calcium carbonate(CaCO3) on the membrane. The scale formed on membrane has to be removed, because the flux can be severely reduced and membrane wetting can be incurred. This study was carried out to investigate scale formation and effectiveness of acid cleaning in vacuum membrane distillation for SWRO brine treatment. It was found that permeate flux gradually declined until volume concentration factor(VCF) reached around 1.55 and membrane wetting started over VCF over 1.6 in the formation of precipitates containing CaSO4 during VMD operation. In contrast, when calcium carbonate formed on membrane, permeate flux was gradually reduced until VCF 3.0. The precipitates containing both CaSO4 and CaCO3 were formed on the membrane surface and in the membrane pore.

• 황태문(한국건설기술연구원) | Tae-Mun Hwang (Korea Institute of Civil Engineering and Building Technology) Corresponding author
• 장은경(한국건설기술연구원) | Eun-Kyung Jang (Korea Institute of Civil Engineering and Building Technology)
• 남숙현(한국건설기술연구원) | Sook-Hyun Nam (Korea Institute of Civil Engineering and Building Technology)
• 구재욱(한국건설기술연구원) | Jae-Wuk Koo (Korea Institute of Civil Engineering and Building Technology)
• 김은주(한국건설기술연구원) | Eun-Ju Kim (Korea Institute of Civil Engineering and Building Technology)