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Concentration Polarization in Hyperfiltration Systems

  • W. Pusch

Abstract

When using hyperfiltration membranes for brackish or seawater desalination, an enrichment of the solute (concentration polarization) always occurs at the membrane surface juxtaposed with the brine solution. This is due to the formation of a boundary layer separating the membrane surface from the bulk flow. The thickness of this boundary layer is dependent upon the stirring or streaming velocity. Because the salt transport within the boundary layer is not affected by the bulk flow, the rejected salt at the membrane surface must return to the bulk flow by means of diffusion only. This diffusion of salt into the well stirred or streaming solution is counterbalanced by the convective salt flux (associated with the permeation of water through the membrane), thereby forming a concentration gradient within the boundary layer. The enhanced salt concentration at the membrane surface results in a lower water flux and salt rejection. Thus, the “intrinsic water flux” and the “intrinsic salt rejection”, which would be observed without concentration polarization, are always greater than the observed water flux and salt rejection. The effect of concentration polarization upon volume flow, q, and salt rejection, robs, of a membrane was first investigated by Merten[1]. He showed that the volume flow is limited by concentration polarization because of the effect on local osmotic pressure.

Keywords

Membrane Surface Mass Transfer Coefficient Boundary Layer Thickness Concentration Polarization Bulk Flow 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    U. Merten, Ind. Eng. Chem. Fundamentals, 2, 229 (1963).CrossRefGoogle Scholar
  2. 2.
    U. Merten, H. K. Lonsdale, and R. L. Riley, Ind. Eng. Chem. Fundamentals, 3, 210 (1964).CrossRefGoogle Scholar
  3. 3.
    W. Banks and A. Sharpies, “The Mechanism of Desalination by Reserve Osmosis and its Relation to Membrane Structure”, Office of Saline Water Res. Develop. Progr. Rept. No. 143, June 1965.Google Scholar
  4. 4.
    T. K. Sherwood, P.L.T. Brian, R. E. Fisher, and L. Dresner, Ind. Eng. Chem. Fundamentals, 4, 113 (1965).CrossRefGoogle Scholar
  5. 5.
    R. J. Raridon, L. Dresner, and K. A. Kraus, Desalination, 1, 210 (1966).CrossRefGoogle Scholar
  6. 6.
    P.L.T. Brian in Desalination by Reverse Osmosis, U. Merten (Ed.), M.I.T. Press, Cambridge, Mass. 1966, pp. 161–202.Google Scholar
  7. 7.
    A. J. Shor, K. A. Kraus, J. S. Johnson, and W. T. Smith, Ind. Eng. Chem. Fundamentals, 7, 44 (1968).CrossRefGoogle Scholar
  8. 8.
    T. K. Sherwood, Chem. Eng. Progr. Symp. Ser., 55, 71 (1959).Google Scholar
  9. 9.
    Chandrasekhar, Hydrodynamic and Hydromagnetic Stability, Academic Press, New York, 1954.Google Scholar
  10. 10.
    R. Gröpl and W. Pusch, Desalination, 8, 277 (1970).CrossRefGoogle Scholar
  11. 11.
    J. D. Sheppard and D. G. Thomas, A.I.Ch.E. Journal, 17, 910 (1971).CrossRefGoogle Scholar
  12. 12.
    D. G. Thomas, Ph.H. Hayes, W. R. Mixon, J. D. Sheppard, W. L. Griffith, and R. M. Keller, Environmental Sci. and Technology, 4, 1129 (1970).CrossRefGoogle Scholar
  13. 13.
    D. G. Thomas, A.I.Ch.E. Journal, 11, 520 (1965).CrossRefGoogle Scholar
  14. 14.
    D. G. Thomas, A.I.Ch.E. Journal, 11, 848 (1965).CrossRefGoogle Scholar
  15. 15.
    D. G. Thomas, A.I.Ch.E. Journal, 12, 124 (1966).CrossRefGoogle Scholar
  16. 16.
    J. S. Watson and D. G. Thomas, A.I.Ch.E. Journal, 13, 676 (1967).CrossRefGoogle Scholar
  17. 17.
    H. Strathmann, “Control of Concentration Polarisation in Reverse Osmosis Desalination of Water”, Office of Saline. Water Res. Develop. Progr. Rept. No. 336, April 1968;Google Scholar
  18. H. Strathmann and B. Keilin, Desalination, 6, 179 (1969).CrossRefGoogle Scholar
  19. 18.
    H. J. Bixler and R. A. Cross, “Final Report on Control of Concentration Polarization in Reverse Osmosis Desalination of Water”, Office of Saline Water Res. Develop. Progr. Rent. No. 469, October 1969.Google Scholar
  20. 19.
    A. S. Berman, J. Appl. Phys., 24, 1232 (1953).CrossRefGoogle Scholar
  21. 20.
    T. K. Sherwood, P.L.T. Brian, and R. E. Fisher, MIT Desalination Research Laboratory, Rept. 295–1, August 1963.Google Scholar
  22. 21.
    J. S. Johnson, Jr., L. Dresner, and K. A. Kraus in Principles of Desalination, by K. S. Spiegler (Ed.), Academic Press, New York, 1966, pp. 345–439.Google Scholar
  23. 22.
    L. Dresner, Oak Ridge Natl. Lab. Rept. No. 3621, May 1964.Google Scholar
  24. 23.
    R. E. Fisher, T. K. Sherwood, and P.L.T. Brian, MIT Desalination Research Laboratory, Rept. 295–5, 1964.Google Scholar
  25. 24.
    W. N. Gill, Chi Tien, and D. W. Zeh, Intl. J. Heat Mass Transfer, 9, 907 (1966).CrossRefGoogle Scholar
  26. 25.
    W. N. Gill, Chi Tien, and D. W. Zeh, Ind. Eng. Chem. Fundamentals, 4, 433 (1965).CrossRefGoogle Scholar
  27. 26.
    H. Goldsmith and H. Lolachi, Office of Saline Water Res. Develop. Progr. Rept. No. 527, May 1970.Google Scholar

Copyright information

© Plenum Press, New York 1972

Authors and Affiliations

  • W. Pusch
    • 1
  1. 1.Max-Planck-Institut für Biophysik6 Frankfurt am MainGermany

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