In filtration, the use of ‘filter aid’ helps in__________________?

Related Mcqs:

1. The basic filtration equation is given as dt/dV = (μ/A ΔP). [(α .CV/A) + Rm], where, V is volume of the filtrate; A is the filtration area, a is specific cake resistance, μ is viscosity of the filtrate, and C is the concentration of the solids in the feed slurry. In a 20 minutes constant rate filtration, 5 m3 of filtrate was obtained. If this is followed by a constant pressure filtration, how much more time in minutes, it will take for another 5 m3 of filtrate to be produced? Neglect filter medium resistance, Rm; assume incompressible cake ?

   A. 10
   B. 20
   C. 25
   D. 30

2. Filter aids like asbestos, kieselguhr, diatomaceous earth etc. are used to increase the porosity of the final filter cake & reducing the cake resistance during filtration. Filter aid is_______________?

   A. Added to the feed slurry
   B. Pre-coated on the filter medium prior to filtration
   C. Separated from the cake by dissolving solids or by burning it off
   D. All A, B. & C.

3. The cake resistance increases steadily with the time of filtration in a plate and frame filter employing constant ______________ filtration?

   A. Rate
   B. Pressure
   C. Both A. & B.
   D. Neither A. nor B.

4. Addition of filter aid to the slurry before filtration is done to _______________ of the cake?

   A. Increase the porosity
   B. Increase the compressibility co-efficient
   C. Decrease the porosity
   D. Decrease the compressibility co-efficient

5. Filtration operation carried out by continuous increase of the inlet pressure of slurry, is called the _____________ filtration?

   A. Constant rate
   B. Varying pressure
   C. Varying rate
   D. Constant pressure

6. A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ρL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is δ and no cake is formed. The initial pressure drop during filtration is ___________________?

   A. ½w2 . R2 . ρL
   B. ½w2 . δ2 . ρL
   C. ½w2 . δρL (2R + δ)
   D. ½w2 . R . ρL(R + 2δ)

7. Filtration capacity of a rotary drum vacuum filter depends upon the_______________?

   A. Cake thickness
   B. Characteristics of the feed slurry
   C. Both A. & B.
   D. Neither A. nor B.

8. During washing of filter at the end of constant pressure filtration, the rate of washing equals the rate of filtration___________________?

   A. At time zero
   B. At the end of filtration
   C. When half the filtrate has been obtained
   D. At the end of filtration, but decreases with time subsequently

9. Filtration rate through a filter cake is proportional to (where, S = filtering surface R = specific cake resistance μ = viscosity of the filtrate) ?

   A. S
   B. 1/R
   C. 1/μ
   D. All A., B. & C.

10. Filter medium resistance is important during the ______________ of filtration?

    A. Early stages
    B. Final stages
    C. Entire process
    D. None of these