heat and mass transfer please answer for a like, your pretty much describing please solve, thank you

1) Selection of Fick's Law or the Mass Transfer Correlation Learning Objective: Understanding when to apply Fick's Law of diffusion and when to apply the mass transfer coefficient MTC) model. Explain whether the mass transfer coefficient model or Fick's law would be best used for parts a) and b) below. You are designing a wastewater bioremediation system that flows water over a microbial biofilm (i.e., slime) that is growing on the surface of particles in a packed bed. There are two important mass transfer issues here. One is to understand the degradation rates of different chemicals in the wastewater by the microbes within the biofilm, which will be affected by the rate at which the chemicals reach the bacteria. The other is to know how the average concentration of oxygen in the bulk fluid changes along the length of the bed as the oxygen is consumed by the bacteria. The questions are which model(s) would be most useful in evaluating these conditions to aid design of an effective bioremediation system. Concisely identify the primary advantage(s) of the model you choose relative to the other in each case. The same model might or might not be used for each case. Extensive discussion is not expected - it is the key concepts that should be presented. a) The change of dissolved oxygen concentration in the wastewater as it flows through the bed. b) The penetration of the pollutant into the biofilm and then into the microbial cells