INVESTIGADORES
RAJAL Veronica Beatriz
artículos
Título:
The continuum heterogeneous biofilm model with multiple limiting substrate Monod kinetics
Autor/es:
ELIO E. GONZO; STEFAN WUERTZ; RAJAL, VERONICA
Revista:
BIOENGINEERING AND BIOTECHNOLOGY
Editorial:
JOHN WILEY & SONS INC
Referencias:
Lugar: New York; Año: 2014 vol. 111 p. 2252 - 2264
ISSN:
0006-3592
Resumen:
We describe a novel procedure to estimate the
net growth rate of biofilms on multiple substrates. The
approach is based on diffusion-reaction mass balances for
chemical species in a continuum biofilm model with reaction
kinetics corresponding to a Double-Monod expression. This
analytical model considers a heterogeneous biofilm with
variable distributions of biofilm density, activity, and effective
diffusivity as a function of depth.We present the procedure to
estimate the effectiveness factor analytically and compare the
outcome with values obtained by the application of a rigorous
numerical computational method using several theoretical
examples and a test case. A comparison of the profiles of the
effectiveness factor as a function of the Thiele modulus, f,
revealed that the activity of a homogeneous biofilm could be
as much as 42% higher than that of a heterogeneous biofilm,
under the given conditions. The maximum relative error
between numerical and estimated effectiveness factor was
2.03% at f near 0.7 (corresponding to a normalized Thiele
modulus f ¼1). For f1.4, the relative error
was less than 0.5%. A biofilm containing aerobic ammonium
oxidizers was chosen as a test case to illustrate the model?s
capability. We assumed a continuum heterogeneous biofilm
model where the effective diffusivities of oxygen and
ammonium change with biofilm position. Calculations
were performed for two scenarios; Case I had low dissolved
oxygen (DO) concentrations and Case II had high DO
concentrations, with a concentration at the biofilm?fluid
interface of 10 gO2/m3. For Case II, ammonium was the limiting substrate for a biofilm surface concentration, CNs,
13.84 g of N/m3. At these concentrations ammonium was
limiting inside the biofilm, and oxygen was fully penetrating.
Conversely, for CNs>13.84 g of N/m3, oxygen became the
limiting substrate inside the biofilm and ammonium was fully
penetrating. Finally, a generalized procedure to estimate the
effectiveness factor for a systemwith multiple (n>2) limiting
substrates is given.