An ion exchange resin is used to soften water. The ion exchange resin has a volume of 0.15 m3and a resin capacity of 63 kg CaCO3/m3. The flow of water is measured as 2500 L/day, the influent hardness is 340 mg/L as CaCO3 and the desired hardness is 70 mg/L as Ca CO3. If 25% of the water is bypassed, how long can the resin operate before all sites are saturated and regeneration required?

Amixture of slurry and mud is to be pumped through a horizontal pipe of diameter 500 mm. the fluid behaves as a bingham plastic with a yield stress of 30 pa and viscosity 0.04 pa. s. describe the effects of the shear stress through a transverse section of the pipe by plotting the variation in shear stress and velocity profile: (i) just before the slurry starts to move (ii) as the slurry flows when the pressure gradient is double that in part (i)