Journal of Korean Society of Water and Wastewater (상하수도학회지)

The Korean Society of Water and Wastewater (대한상하수도학회)
권호 표지

Reduction of Cake Resistance by Floc Reaggregation in a Membrane-Feed-Pipe

관내 입자 재응집에 의한 케이크 저항의 감소

  • Received : 2007.09.10
  • Accepted : 2007.12.06
  • Published : 2007.12.15
Download PDF
⟨ Previous Next ⟩

Abstract

Fully-grown flocs in a mixing tank of membrane filtration with dead-end membrane are ruptured while passing through a pump and the ruptured flocs are aggregated again in a Membrane-Feed-Pipe (MFP). To look at more details, this study tries to relate the reaggregation to a parameter of mixing intensity in MFP, i.e., G-value. The G-value is a function of Reynolds number, pipe diameter, friction factor and average velocity in MFP. To deal with polydispersity condition, we develop a representative particle size called in this study EDPD (Effective Diameter for Polydispersity condition in Dead-end filtration). The experimental results show that as the G-value increases, the EDPD decreases and also the cake resistance increases. Through comparison between EDPD and cake resistance, these results show that cake resistances are controlled by reaggregation phenomenon in MFP. The effect of detention time in MFP, however, does not affect the reaggregation of the broken flocs as G-values are increased.

Keywords

Acknowledgement

Supported by : 한국학술진흥재단

References

  1. Altmann, J. and Ripperger, S. (1997) Particle deposition and layer formation at the crossflow microfiltration, J. Mem. Sci., 124, pp. 119-128 https://doi.org/10.1016/S0376-7388(96)00235-9
  2. M.M. Clark (1985) Critique of camp and stein's rms velocity gradient, J. Emnron. Eng., 116(6), pp. 741-754
  3. M.M. Clark, and J.R.V. Flora (1991) Floc restructuring in varied turbulent mixing, J. colloid and interface sci., 147(2), pp. 407 -421 https://doi.org/10.1016/0021-9797(91)90174-7
  4. Graber, S.D. (1994) A critical review of the use of the Gvalue (RMS velocity gradient) in environmental engineering, Dev Tbeor. Appl. Mech., 17, pp. 533-556
  5. Godfrey, J.C., Amirtharajah, M.M. Clark (1991) Mixing in coagulation and flocculation, AWARF. Denver
  6. Kim, S., Cho, S.H., and Park, H. (2002) Reduction of cake layer by re-aggregation in coagulation-crossflow microfiltration process, Water Sci. and Technol.: Water Supply, 2(5-6), pp. 329-336
  7. Kim, S. (2003) Characteristics and control of cake formation in crossflow microfiltration at polydisperse condtion, Ph.D. thesis, Dept. of Civil and Environmental Engineering, KAIST, Daejeon, South Korea
  8. Kim, S., and Park, H. (2005) Effective diameter for shearinduced diffusion for characterizing cake formation in crossflow microfiltration at polydisperse conditions, J. Environ. Eng., 131(6), pp. 865-873 https://doi.org/10.1061/(ASCE)0733-9372(2005)131:6(865)
  9. Kim, S., Park, N., Kim. T., Park, H. (2007) Reaggregation of floes in coagulation-cross-flow microfiltration, J. Environ. Eng., 133(5), pp. 507-514 https://doi.org/10.1061/(ASCE)0733-9372(2007)133:5(507)
  10. Kwon, D.Y. (1998) Experimental investigation on Critical flux in cross-flow microfiltration, Ph.D. thesis, Faculty of Engineering and Environmental Engineering Group, Univ. of Technology, Sydney, Australia
  11. Lee, J.D., Lee, S.H., Jo, M.H., Park, P.K., Lee, J.H., Kwak, J.W. (2000) Effect of coagulation conditions on membrane filtration characteristics in coagulation-microfiltration process for water treatment, Environ. Sci. Technol., 34, pp. 3780-3788 https://doi.org/10.1021/es9907461
  12. MaLaughlin J.B. (1993) The lift on a small sphere inwallbounded linear shear flows, J. Fluid Mech., 246, pp. 249-265 https://doi.org/10.1017/S0022112093000114
  13. Mehmet A. Y., John G. (2004) The effect of rapid mixing on the break-up and re-formation of floes, J. Chemi Technol Biotechnol., 79, pp. 782-788 https://doi.org/10.1002/jctb.1056
  14. R.J. Latimer, Appiah Amirtharajah (1998) Pilot scale comparison of static mixers and backmix reactors for coagulation, AWWA Annual Conference, pp. 705-740
  15. S. Casey Jones, Fotis Sotiropoulos, and Appiah Amirtharajah. (2002) Numerical modeling of helical static mixers for water treatment, J. Environ. Eng., 128(5), pp. 431-440 https://doi.org/10.1061/(ASCE)0733-9372(2002)128:5(431)
  16. Smoluchoski, M. (1917). Versuch einer mathematischen Theorie der Koagulationskinetic kolloider L sungen, Z. Phys. Chem., 92, pp. 129-168
  17. Soffer, Y., Ben, A.R., and Adin, A. (2000) Membane for water reuse: effect of pre-coagulation on fouIing and selectivity, Water Sci. Technol., 42(1-2), pp. 367-372 https://doi.org/10.2166/wst.2000.0340
  18. Wiesner, M.R., Clark, M.M., and Mallenvialle, J. (1989) Membrane filtration of coagulated suspensions. J. Environ. Eng., 115(1), pp. 20-40 https://doi.org/10.1061/(ASCE)0733-9372(1989)115:1(20)
  19. Yukselen, M.A., and Gregory, J. (2002) Breakage and Reformation of Alum flocs, Environ. Eng., Sci., 19(4), pp. 229-236 https://doi.org/10.1089/109287502760271544
  20. Yukselen, M.A., Gregory J. (2004) The effect of rapid mixing on the break-up and re-formation of floes, J. Chemi Technol Biotechnol., 79, pp. 782-788 https://doi.org/10.1002/jctb.1056