Bulk liquid Diffusion layer Solid surface Biofilm A biofilm with a thickness Lf (cm) grows on the surface of a solid. After traversing a diffusion layer (diffusivity: D) of thickness L (cm), a chemical compound A diffuses into the biofilm (diffusivity: Dr) where it is subject to an irreversible first-order decomposition that converts it to products AP, governed by a rate law ra = - kCA, where k is the reaction rate constant. Derive transient models that describe the concentration profile within the diffusion layer and biofilm layer! Define the boundary conditions to solve LI 0 the transient model! Note: concentration of A at bulk liquid is CAO