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2012-04-21 16:35:17
Wastewater Treatment biofilm

Biology in WW Treatment
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  1. Ssb
    substrate concentration of bulk liquid
  2. Dispersion
    Movement of a substance due to moentum exchange between fulid elements in turbulent flow. How the blob gros in size as it moves by advection
  3. Diffusion
  4. Advection
    bulk movement of mass along a trajectory
  5. Area where active biomass dominates
    Outer regions
  6. area where debris biomass dominates
    Inner regions
  7. When competeing only for space, if species A has a higher mu max than B, where will A dominate? B? Why?
    A in outer regions, B in inner regions. By the inner regions, substrate concentration for Species A will be diminshed to allow B to grow faster than A
  8. Lw
    Thickness of hypothetical boundary layer
  9. What is the hypothetical boundary layer?
    stagnant laywer where resistance to mass transfer from the bulk fluid to the biofilm occurs
  10. SSs
    concentration of substrate at biofilm surface
  11. Dw
    diffusivity across the hypothetical boundary layer, used in external mass transfer equation
  12. Js
    Flux or mass of substrate transported per unit area per unit time.
  13. k*L
    Dimensionless external mass coefficient. Represents the imporatnce of external mass transfer resistence on performance of biofilm. (>10 means external mass transfer resistance is not important) but (<1 indicates important)
  14. kL
    liquid phase mass transfer coefficient, includes diffusivity and convective mass transfer.
  15. kL (and Lw) depends on ...
    viscosity and density of fluid, diffusivity of substrate in the fluid and turbulence.
  16. Mass transfer within the biofilm is dominated by ...
    Fick's Law
  17. Larger velocity ______ thickness of hypothetical boundary layer
  18. De
    Effective diffusivity - usually smaller than free diffusivity due to EPS. Used for internal mass transfer equations.
  19. Three techniques for combingin biofilm model with process model
    direct tehcnique; effectiveness factor technique; pseudoanalytical technique
  20. Pseudoanalytical technique
    develps a relationship between reaction rate and bulk substrate concentration to be used in bioreactor model. Allows calculation of bulk substrate concentration and biofilm thickness
  21. Lf
    Steady state uniform thickness of the biofilm
  22. YH
    True growth yield for heterotrophs (COD units)
  23. bH
    Traditional decay coefficient for heterotrophs
  24. bD
    loss coefficient due to detachment caused by surface shear. Dependent on flow velocity
  25. SSbmin
    Minimum bulk substrate concentration for biofilm to grow rapidly enough to replace loss from decay
  26. J*S,deep
    dimensionless flux into a deep biofilm
  27. S*Ss
    dimensionless substrate concentration at the liquid-biofilm interface
  28. J*S
    dimensionless flux into an actual biofilm
  29. fudge factor?
  30. S*Sbmin or RI
    Rittman number of dimensionless minimum bulk substrate concentration
  31. Why is S*Sbmin important?
    Ratio of specific loss rate of biomass to net potential growth rate. Large values (>1) indicates biofilm will be difficult to maintain
  32. SSO
    initial substrate concentration
  33. As
    total surface area of biofilm
  34. as
    speficic surface area of media. surface area per unit volume
  35. JSR
    reference flux - minimum flux required to maintain a steady state biofilm that is deep.