Waste Water Engineering Multiple Choice Questions on “Ultrafiltration”.
1. Ultrafiltration is different from membrane filtration.
a) True
b) False
Answer: b
Clarification: In ultrafiltration, semi-permeable membranes are used. In this filtration forces like pressure or concentration gradients lead to a separation through a semipermeable membrane.
2. __________ is used for ultrafiltration.
a) Permeable membrane
b) Highly permeable membrane
c) Semi-permeable membrane
d) Non-permeable membrane
Answer: c
Clarification: A separation through a semipermeable membrane is achieved. Water and low molecular weight solutes pass through the membrane in permeate (filtrate) while suspended solids and solutes of high molecular weight are retained on the retentate.
3. High molecular weight solutes pass through the membrane.
a) True
b) False
Answer: b
Clarification: Water and low molecular weight solutes pass through the membrane in permeate (filtrate) while suspended solids and solutes of high molecular weight are retained on the retentate.
4. Which of the following factors are considered in ultrafiltration?
a) Size
b) Colour
c) Taste
d) Smell
Answer: a
Clarification: Ultrafiltration is not fundamentally different from micro filtration. In membrane gas separation, it separates based on different amounts of absorption and different rates of diffusion.
5. Which of the following is a tertiary filtration?
a) Coagulation
b) Sand filtration
c) Flocculation
d) Sedimentation
Answer: b
Clarification: It has been used to either replace existing secondary (coagulation, flocculation, sedimentation) and tertiary filtration (sand filtration and chlorination) systems employed in water treatment plants or as standalone systems in isolated regions with growing populations.
6. Which of the following is not correct with respect to ultrafiltration?
a) Chemicals required
b) Compact plant size
c) Good product quality
d) Good pathogen removal
Answer: a
Clarification: The plant size required for the operation of ultrafiltration is compact and the product quality is good with good pathogen removal. There are no chemicals required for the process.
7. Macromolecules deposited uniformly on pore walls is called ______
a) Standard blocking
b) Complete blocking
c) Intermediate blocking
d) Blocking
Answer: a
Clarification: Macromolecules deposited uniformly on pore walls is called standard blocking. The membrane pore completely sealed by a macromolecule is called complete blocking.
8. Which of the following factors does not stimulate scale formation?
a) pH
b) Temperature
c) Area
d) Flow velocity
Answer: c
Clarification: The inorganic salt deposits can block pores causing flux decline, membrane degradation and loss of production. The formation of scale depends on factors like solubility and concentration polarization including pH, temperature, flow velocity and permeation rate.
9. Micro-organisms adhering to the membrane surface forming a gel layer is called ______
a) Scaling
b) Biofilm
c) Gel layer
d) Barrier
Answer: b
Clarification: Micro-organisms will adhere to the membrane surface forming a gel layer – known as a biofilm. The film increases the resistance to flow, acting as an additional barrier to permeation.
10. What is the turbidity for hollow fibers?
a) <15
b) <1
c) <10
d) <12
Answer: a
Clarification: The turbidity of the hollow fiber is less than 15. The turbidity of spiral-wound is less than 1 and that of ceramic tubes is less than 10.
11. Which of the following materials are used for high temperature applications?
a) Polypropylene
b) Cellulose acetate
c) Polylactic acid
d) Ceramic
Answer: d
Clarification: Most ultrafiltration membranes use polymer materials such as polypropylene, cellulose acetate and Polylactic acid. However, ceramic membranes are used for high temperature applications.