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
bulk movement of mass along a trajectory
Area where active biomass dominates
area where debris biomass dominates
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
Thickness of hypothetical boundary layer
What is the hypothetical boundary layer?
stagnant laywer where resistance to mass transfer from the bulk fluid to the biofilm occurs
concentration of substrate at biofilm surface
diffusivity across the hypothetical boundary layer, used in external mass transfer equation
Flux or mass of substrate transported per unit area per unit time.
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)
liquid phase mass transfer coefficient, includes diffusivity and convective mass transfer.
kL (and Lw) depends on ...
viscosity and density of fluid, diffusivity of substrate in the fluid and turbulence.
Mass transfer within the biofilm is dominated by ...
Larger velocity ______ thickness of hypothetical boundary layer
Effective diffusivity - usually smaller than free diffusivity due to EPS. Used for internal mass transfer equations.
Three techniques for combingin biofilm model with process model
direct tehcnique; effectiveness factor technique; 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
Steady state uniform thickness of the biofilm
True growth yield for heterotrophs (COD units)
Traditional decay coefficient for heterotrophs
loss coefficient due to detachment caused by surface shear. Dependent on flow velocity
Minimum bulk substrate concentration for biofilm to grow rapidly enough to replace loss from decay
dimensionless flux into a deep biofilm
dimensionless substrate concentration at the liquid-biofilm interface
dimensionless flux into an actual biofilm
S*Sbmin or RI
Rittman number of dimensionless minimum bulk substrate concentration
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
initial substrate concentration
total surface area of biofilm
speficic surface area of media. surface area per unit volume
reference flux - minimum flux required to maintain a steady state biofilm that is deep.