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DOI : 10.17640/KSWST.2018.26.5.3 , Vol.26, No.5, 3 ~ 16, 2018
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| Title |
| Control of Membrane Fouling by Inorganic Salts in Vacuum Membrane Distillation |
| 황태문 Tae-mun Hwang , 장은경 Eun-kyun Jang , 구재욱 Jae-wuk Koo , 남숙현 Sook-hyun Nam , 김은주 Eun-ju Kim |
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| Abstract |
| High concentration of calcium ion, sulfate ion, bicarbonate ion in SWRO(Seawater Reverse Osmosis) brine, calcium sulfate and calcium carbonate can be formed during treating SWRO brine. In addition, the solubility of calcium sulfate and calcium carbonate is very low, accordingly, the scale formation is unavoidable problem when SWRO brine is treated by VMD(Vacuum Membrane Distillation) and can be main obstacle for VMD to apply to desalination and other treatment. Thus, This study was carried out to evaluate anti-scalant and acidic agent to control inorganic membrane fouling in the lab-scale VMD system. Saturated CaSO4 and CaCO3 solution were used as a model scalant. In the case of anti-scalant injection of high concentration TDS solution containing model scalants, the time of the scale foramtion was shorter as the TDS concentration increases. Also, in the VMD filtration experiment, a sharp decrease in permeate flux was observed at about VCF(Volume Concentration Factor) 1.5. Comparing the change of the permeation flux before and after the injection of the anti-scale agent, the scale formation was delayed by about VCF 0.2 when the anti-scale agent was injected. Although the scale inhibitor has an effect of delaying scale formation, it can be confirmed that the effect is insufficient. On the other hand, the experimental results of membrane cleaning using distilled water showed that the permeate flux was temporarily restored, but membrane wetting occured in a short time. Acid flushing with 5% hydrochloric acid did not cause membrane wetting, and permeate flux was stably maintained. As a result of the analysis of the membrane surface, it was confirmed that all the scale substances on the membrane surface were removed. |
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| Key Words |
| Anti-scalant, CaCO3, CaSO4, Membrane fouling, Vacuum MD |
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