Temperature Effect in the process of DAF as pretreatment of SWRO

해수담수화 전처리로서 DAF공정에서 고온의 해수에 대한 영향 특성

  • 박현진 (단국대학교 토목환경공학과) ;
  • 독고석 (단국대학교 토목환경공학과)
  • Received : 2012.11.13
  • Accepted : 2012.12.10
  • Published : 2012.12.15


Flocculation and flotation are used as pretreatment steps prior to the reverse osmosis (RO) process. During seawater treatment, high temperature can change the water chemistry of seawater during the process of coagulation. It also affects bubble volume concentration (BVC) and bubble characteristics. Coagulants such as alum and ferric salts at $40^{\circ}C$ can also change flux rates in the seawater reverse osmosis (SWRO) process. In this study, the bubble characteristics in dissolved air flotation (DAF), used as a SWRO pretreatment process, were studied in synthetic seawater at $20^{\circ}C$ and $40^{\circ}C$. The flux of an RO membrane was monitored after dosing the synthetic seawater with coagulants at different temperatures. Results showed that BVC increases as the operating pressure increases and as the salt concentration decreases. The bubble size released at $40^{\circ}C$ is far smaller than that at $20^{\circ}C$The addition of a ferric salt is effective for turbidity removal in synthetic seawater at $20^{\circ}C$; it is more effective than alum. When synthetic seawater was dosed with a ferric salt, the RO membrane flux increased by 27 % at $40^{\circ}C$.


  1. Ahn, H. W., Kwon S.B., Kwak D.H., Wang C.G, Dockko S., Park G.H. (2006) Drinking water treatment applying to DAF process. p.147, K water, Daejeon.
  2. Chen, F., Peng, F., Wu, X., Luan, Z. (2004) Bubble performance of a novel dissolved air flotation (DAF) unit. Journal of Environmental Science. 16, 104-107.
  3. Edzwald, J.K. (2007) Principles and application of dissolved air flotation. Water science & technology, 31(3-4), 1-23.
  4. Edzwald, J.K. (2010) Water Quality & Treatment: A handbook on Drinking water. 6th edition. McGraw-Hill Prof Med/Tech, New York.
  5. Edzwald, J.K. and Haarhoff, J. (2011) Seawater pretreatment for reverse osmosis: Chemistry, contaminants, and coagulation. Water Research, 45, 5428-5440.
  6. Han, M. Y., Park, Y.H., Kwak, D.H. and Kim, I.K. (2001) Development of measuring bubble size in flotation process using on-line particle counter. Journal of KSWW, 15(6), 559-565.
  7. Han, M. Y. and Park, Y.H. (2003) "Assessment of the treatability oh highly turbid water by dissolved air flotation", Second IWA Asia-Pacific Regional Conference 2003 Asian Waterqual, Bangkok, Thailand.
  8. Kawahara, A., Sadatomi, M., Matsuyama, F., Matsuura, H., Tominaga, M., Noguchi, M. (2009) Prediction of micro-bubble dissolution characteristics in water and seawater. Experimental Thermal and fluid Science, 33, 883-894
  9. Kim, T. I. (2010) Analysis of bubble potential energy and its application to disinfection and oil washing. PHD thesis, Seoul National University, Seoul.
  10. Moruzzi , R.B. and Reali, M.A.P. (2010) Characterization of micro-bubble size distribution and flow configuration in DAF contact zone by a non-intrusive image analysis system and tracer tests. Water science & technology, 61(1), 253-262.
  11. Park, Y.H. (2001) Effect of pressure in dissolved-air-flotation. MS thesis, Seoul National University, Seoul.
  12. Pernitsky, D.J. and Edzwald, J.K. (2003) Solubility of polyaluminum coagulants. Journal of Water Supply: Research and Technology - Aqua, 52 (6), 395-406.
  13. Rodrigues, R.T. and Rubio, J. (2003) New basis for measuring the size distribution of bubbles. Minerals Engineering, 16, 757-765.
  14. Shu, L., Qunhui, W., Hongzhi, M., Peikun, H., Jun, L., Takashige, K. (2009) Effect of micro-bubbles on coagulation flotation process of dyeing wastewater. Separation and Purification Technology, 71, 337-346.
  15. Walker A.B., Tsouris C., DePaoli D.W. and Klasson K.T. (2001) Ozonation of soluble organics in aqueous solutions using microbubbles. Ozone Science and Engineering, 23, 77-87.

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