Assume that the water temperature is 10°C and the depth of the settling tank is 3.0 m. Calcium carbonate precipitates with a relative density of 1.20 and diameter of 0.10 mm to be removed in a settling tank after softening treatment. Assume discrete particle settling. At 10°C the density and viscosity of water are 999.77 kg/m3 and 1.308x10-3 kg/m. s.
a. Calculate the theoretical settling velocity (cm/s), tank loading (m3 /m2 /d) and detention time (h) required for the removal.
b. How will the settling velocity change, if the viscosity, particle diameter, and the relative density increases by 10%? How will the settling velocity change if the water temperature is 25 oC instead of 10 oC? Vary only one parameter at a time.