Choose only ONE question from the below. 5. A blue-green alga grown in a 10 m chemostat is used to treat ammonia in wastewater, at 25C. Sterile ammonia solution containing 1.0 g/L N is fed to the tank. The maximum specific growth rate of the alga is 0.45 day, and the yield of biomass on nitrogen is 18 g/g N. Monod equation is applicable, with the substrate constant for N 0.5 mg/L. No extracellular products are formed. (20 marks =8+12) a. Determine the dilution rate (day-) in order to remove 99% ammonia from the inlet and how much wastewater can be treated by this system per day. b. In order to remove ammonia from 80 m/day wasterwater, an intensification of the culture process is investigated using cell recycle. A recycle stream containing 100 times the concentration of cells in the effluent is fed back to the vessel at a volumetric flow rate that is one-quarter of that of the fresh feed. Determine whether the new process can still remove 99% ammonia? (Tips: material balance)

Choose only ONE question from the below. 5. A blue-green alga grown in a 10m3 chemostat is used to treat ammonia in wastewater, at 25C, Sterile ammonia solution containing 1.0g/LN is fed to the tank. The maximum specific growth rate of the alga is 0.45day1, and the yield of biomass on nitrogen is 18g/gN. Monod equation is applicable, with the substrate constant for N0.5mg/L. No extracellular products are formed. (20 marks =8+12) a. Determine the dilution rate (day1) in order to remove 99% ammonia from the inlet and how much wastewater can be treated by this system per day. b. In order to remove ammonia from 80m3/ day wasterwater, an intensification of the culture process is investigated using cell recycle. A recycle stream containing 100 times the concentration of cells in the effluent is fed back to the vessel at a volumetric flow rate that is one-quarter of that of the fresh feed. Determine whether the new process can still remove 99% ammonia? (Tips: material balance)