Question 3 (25 marks) A reverse-osmosis plant is used to treat 4,730 m/hr of sea water at 20 C containing 3.45 wt% of sodium chloride (salt). A pump was used to increase the pressure of the inlet feed before entering the reverse-osmosis membrane system, in order to produce 1,578 m/hr of drinking water with 500 ppm of salts (Figure Q3). The reject stream is considered as brine containing 5.25 wt% of salts. The permcate side pressure is 50 psia, and the solvent permeability constant can be taken as 2.23 x 10*kg/ms.atm. Assume that the sea water contains only sodium chloride (Pnaci = 2.16 gem") and pure water (Pwater = 998.2 kg/m' at 20C). The required area of the membrane is 1.85 x 10 m (a) Determine the mass flux of solvent, N. (6 marks) (b) Calculate the osmotic pressure for inlet feed in atm using equation of calculations. (Note: Answers obtained through osmotic table would not be considered) (9 marks) (C) Evaluate the osmotic pressure difference, It in atm. (6 marks) (d) Assuming that the food pressure into the membranc is equivalent to the outlet pressure from the pump, estimate the required outlet pressure from the pump in (4 marks) psia RO - stage 1 Brine 5.25% salt Seawater 3.45% salt Pump #1 Drinking water 500 ppen salt Figure Q3