A bio film reactor with a well-mixed liquid phase shown below will be used to treat wastewater contaminated with trichioroethylene (TCE) at a concentration 0.25 mg/L (1.9 mmole/m³, M_TCE= 131.4 g/gmole). The available surface area of the bio film in the reactor is 800 m², and the desired outlet concentration of TCE is 0.05 mg/L (0.05 g/m³). It can be assumed that in a well-mixed, continuous-flow reactor at steady state, the concentration of the solute of the liquid phase of inside the reactor is equal to the concentration of the solute in the liquid flow exiting the reactor. It may also be assumed that the TCE degradation in the bio film, which of δ = 100 μm thickness, proceeds by homogeneous first- order reaction kinetics. 

a. What volumetric flow rate of wastewater is allowed to enter the reactor? The temperature of the process is constant at 20°C. 

b. What is the concentration of TCE in the biofilm at the point where the biofilm is attached to the surface? What fraction of 100 µm thickness of the bio film is utilized? 

Potentially useful data*: k_TCE = 4.3 1 s^-1 (first-order rate constant for TCE in biofilm); D_TCE-biofilm = 9.03 × 10^-10 m²/s (diffusion coefficient TCE in biofilm).

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Waste water feed steam CA = 0.25 g TCE/m³ Vo = ? Biofilm Treated Well-mixed waste water contactor CAo = 0.05 g TCE/m³