1. Crude oil (A) is treated to degrade the total petroleum hydrocarbons using a mixed population of indigenous bacteria and fungi. Reaction rate is expressed as rA=0.04CA Crude oil solution is fed to 250L CSTR with 40 L/min volumetric flow rate. Initial concentration of crude oil is 1g/kg. At time t=0, concentration of crude oil increases to 1.5g/kg due to a technical fault. However, this fault is noticed after 4 minutes and then concentration is set to 1g/kg. a) Write the transfer function and calculate process gain and time constant. (10 pt.) b) Find the output concentration at 2nd and 10th minutes. (20pt.)