A filtration process is carried out at a constant flow rate. Afterwards, the filtration process continues under constant pressure difference conditions of 400 N/m². It is known that 1.2 m³ of filtrate is obtained in 250 seconds at a constant flow rate. Determine the void fraction (E) of the bed if the final permeate volume obtained after a total time of 1000 seconds for the whole process is 4 m³. Assume that the solid particles filtered in the filter cake consist of homogeneous spheres and their radius is 4 cm. Additional Information: A= 1.8 m² ; l= 18cm ; = 1 g/cm.s=0.1 Pa.s

a) 0.24

b) 0.32

C) 0.11

d) 0.16