Question

What is the main driving force for the filtrate flow?

(a) Difference between the atmospheric pressure and the pressure in the equipment

(b) Atmospheric pressure only

(c) Partial pressure only

(d) Difference between the atmospheric pressure and the partial pressure

I have been asked this question during an internship interview.

The doubt is from Filtration at Constant Pressure Drop in section Filtration of Food Processing Unit Operations

Answer 1

The correct option is (a) Difference between the atmospheric pressure and the pressure in the equipment

The explanation: The main driving force for the filtrate flow is difference between the atmospheric pressure and the pressure in the equipment. Though the hydrostatic pressure still contributes to the driving force, it is usually smaller than the vacuum pressure produced by the pump.