According to Darcy’s equation permeability coefficient (K)represents the" *
Surface area of filter medium
Thickness of cake
Pressure drop
Resistance of filter medium and filter cake
Answers
Answer:
This is also called as theory of filtration which gives idea about factors affecting rate of filtration through the filter medium. Any fluid while passing through porous medium offers resistance, the rate of filtration through the filter media is expressed in the form of an equation which is known as Darcy’s law
The equation is, V = KA ∆ P/ µ l
Where , V = Volume of filtrate
K = permeability coefficient & is dependent on filter medium & filter cake.
A = Area of filter bed.
∆P = Pressure drop across filter medium & filter cake.
l = Thickness of filter cake
µ = Viscosity of filtrate
Thus,
According to Darcy’s law different factors which affect rate of filtration are:
1. Surface area of filter media: The rate of filtration is directly proportional to the surface area of filter media. Filter press works on this principle.
2. Pressure difference on the liquid and below the filter medium: The rate of filtration of liquid is directly proportional to the pressure difference between the filter medium and filter cake. Thus, the rate of filtration can be increased by applying pressure on the liquid being filtered or by decreasing the pressure beneath the filter.
3. Viscosity: The rate of filtration is inversely proportional to the viscosity of the liquid undergoing filtration. Liquids which are very viscous get filtered slowly. Reduction of viscosity of a liquid by raising the temperature is frequently done in order to accelerate filtration.
4. Thickness of cake: The rate of filtration is inversely proportional to the thickness of the filter cake formed during filtration. As the filtration process proceeds, thickness of cake increases which decreases the rate of filtration.
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