Waste water feed stream biofilm Well-mixed contactor G САО Treated waste water САД Inert solid CA(z) surface biofilm z=0 z=8
A biofilm consists of living cells immobilized in a gelatinous matrix. A toxic organic solute (species A) diffuses into the biofilm and is degraded to harmless products by the cells within the biofilm. We want to treat 0.2 m3 per hour of wastewater containing 0.14 mole/m of the toxic substance phenol using a system consisting of biofilms on rotating disk as shown below.
thickness of the biofilm is 1 mm and we are interested to reduce the phenol concentration in the outlet stream to 0.025 mole/m3. The rate of disappearance of phenol (species A) within the biofilm is described by the following equation
rA = - KICA Where k1 = 0.0024 s-1
The diffusivity of phenol in the biofilm at the process temperature of 25°C is 2.0x10 10 m2/s. Phenol is equally soluble in both water and the biofilm.
1. The concentration of A in the biofilm is give by Ca = Bisinh(mz) + Bzcosh(mz), the numerical value of m is.
2. Use m = 3 mm^-1, determine the numerical values with units for B1 and B2 with the unit of mole/m3
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