It is intended to size a dissolved air flotation thickener (a physical treatment process) to thicken waste activated sludge (WAS). The flow rate of WAS is 500 m/d with a total suspended solids concentration (TSS) of 4000 mg/L. The bench scale data show that 4 wt% solids content is reached in the float at A/S ratio of 0.02 mg/mg. The fraction of air saturation (f) is 0.8. The operating temperature is 20C and solubility of air at this temperature is 18.7 mL/L. The solids loading rate applied actually in the flotation tank with polymer addition is 220 kg/m.d. i) Draw a process flow diagram for recycle and non-recycle modes. [2 marks] ii) Determine the applied gauge pressure for non-recycle mode in kPa. [6 marks] iii) Determine the solids loading rate in kg/d. [5 marks] iv) Determine the surface area of flotation tank in m for non-recycle mode. [5 marks] v) Determine the applied gauge pressure in kPa if the system is worked with recycle mode at recycle ratio of 0.5. [7 marks]