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QUESTION 3 (PO2, CO2, C4) a) A wastewater containing 200 ppm arsenic was adsorbed by bio-adsorbed avocado seed particles in a packed bed having a diameter of 7 cm and length of 20 cm. The solution enters the bed at a flow rate of 500 g/h. The total amount of the bio-adsorbed use is 100 g. The concentration of the breakthrough curve is given in Table 1 and the breakpoint concentration is set at 0.05. 3 Table 1 Concentration breakthrough curve Time (h) 0 3 3.5 4 4.5 6.7 7.0 8.0 8.5 8.7 9.0 9.3 9.6 c/c. 0.000 0.000 0.005 0.010 0.020 0.040 0.060 0.190 0.400 0.600 0.790 0.890 0.950 i) Determine the total length of unused bed (HUNE) (7 marks) ii) If the breakpoint required increase to 9 h, calculate the new fraction of total capacity used up to the breakpoint. (4 marks) b) A tray of sliced apples with a total surface area of 30 m2 is dried by an air stream flowing parallel to the top surface of the tray at a velocity of 8.5 m/s. The temperature and the humidity of the air are 60 C and 0.06 kg H2O/kg dry air respectively. Determine the rate of drying of the sliced apples in kg/h.m2 during the constant-rate period. Given: Awat 60 C = 2350 kJ/kg