sedimentaion Flashcards by darylle r.

This is where the particles are separated from the liquid by gravitational forces.

a. Hindered settling
b. Sedimentation
c. Free settling

b. Sedimentation

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It includes the _________ from liquid sewage wastes, settling of crystals from the mother liquor, and separation of the liquid-liquid mixture from a solvent extraction.

a. Particles
b. Moving fluid
c. Removal of solids

c. Removal of solids

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When the particles are crowded, they settle at a lower rate. A particle is sufficiently far from the walls of the container and other particles so that it stays and is not affected by them.

a. The first statement is true, The second statement is false.
b. Both statements are true.
c. The first statement is false. The second statement is true
d. Both statements are false

a. The first statement is true, The second statement is false.

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In some sedimentation processes, the purpose is to remove the particles from the fluid stream so that the fluid is free of particle contaminants. Fluid can exist in the form of a liquid or gas, and it can be either stationary or in motion.

a. The first statement is true, The second statement is false.
b. Both statements are true.
c. The first statement is false. The second statement is true
d. Both statements are false

b. Both statements are true.

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It is the proportionality constant and dimensionless

a. Drag force
b. External force
c. Drag coefficient

c. Drag coefficient

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Whenever a particle moves through a fluid, one force will act on the particle.

a. The statement is true
b. The statement is false

b. The statement is false

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The resultant force must be equal to the force due to

a. Acceleration
b. Density
c. External force

a. Acceleration

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Gravity acting_____, buoyant force acting______, and drag force acting ______

a. Downward, downward, upward
b. upward, downward, downward
c. Downward, upward, downward
d. All forces are acting downward

c. Downward, upward, downward

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The buoyant force on the particle will counterbalance the external force and the particle will move relative to the fluid.

a. The statement is true
b. The statement is false

b. The statement is false

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The external force of gravity is needed to impart motion to the particle. Density is not needed between the particle and the fluid.

a. The first statement is true, The second statement is false.
b. Both statements are true.
c. The first statement is false. The second statement is true
d. Both statements are false

a. The first statement is true, The second statement is false.

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What is the process called when a dilute slurry separates by gravity into a clear fluid and a slurry of higher solids concentration?

a. Sedimentation
b. Thickening
c. Filtration
d. Centrifugation

a. Sedimentation

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What is the primary mechanism of sedimentation?

a. Buoyancy
b. Gravity
c. Electromagnetic forces
d. Chemical reactions

b. Gravity

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What is the purpose of a batch settling test?

a. To measure the settling velocity of a slurry
b. To determine the concentration of solids in a slurry
c. To predict the size of a thickener
d. To measure the viscosity of a slurry

a. To measure the settling velocity of a slurry

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What is the purpose of a batch settling test in determining settling velocities and mechanisms of settling?

a. To measure the rate of thickening
b. To determine the settling velocity of particles
c. To predict the size of a thickener
d. To measure the rate of sedimentation

b. To determine the settling velocity of particles

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What happens to the particles in zone B during the batch settling test?

a. They settle at a decreasing rate
b. They settle at a uniform rate
c. They settle at an increasing rate
d. They do not settle

b. They settle at a uniform rate

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What happens to the height z during the batch settling test?

a. It increases
b. It decreases
c. It remains constant
d. It fluctuate

b. It decreases

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What is the clear liquid zone in the batch settling test?

a. Zone A
b. Zone B
c. Zone C
d. Zone D

a. Zone A

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What happens during compression in the batch settling test?

a. Liquid is expelled downward from zone D
b. Liquid is expelled upward from zone D
c. The thickness of zone D increases
d. The thickness of zone D decreases

b. Liquid is expelled upward from zone D

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What is the critical point in the batch settling test?

a. The point where the particles start settling
b. The point where the particles stop settling
c. The point where compression first appears
d. The point where particles settle at a uniform rate

c. The point where compression first appears

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What is the method proposed by Talmage and Fitch for determining thickener area?

a. Coe and Clevenger procedure
b. Kynch method
c. Talmage and Fitch procedure
d. Batch settling tes

c. Talmage and Fitch procedure

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For many cases in settling, a small number of particles are present. The velocity gradients surrounding each particle are affected by the close presence of other particles.

a. The first statement is true. The second statement is false.
b. Both statement are true
c. The first statement is false. The second statement is true
d. Both statements are false

a. The first statement is true. The second statement is false.

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In settling, the surrounding particles interfere with the motion of ______ particles.

a. Group
b. Individual
c. Single
d. Combined

b. Individual

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The particles in settling in the liquid displace the solid. An appreciable downward velocity of the liquid is generated.

a. The first statement is true. The second statement is false.
b. Both statement are true
c. The first statement is false. The second statement is true
d. Both statements are false

d. Both statements are false

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The velocity of the liquid is appreciably ____ with respect to the particle than with respect to the apparatus itself.

a. Greater
b. Lower
c. Constant
d. NOTA

a. Greater

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The true drag force is greater in the suspension because? a. Because of the higher effective viscosity of the particle. b. Because of the assistance of other particles. c. Because of the interference of other particles. d. NOTA

c. Because of the interference of other particles.

The higher viscosity of the mixture is equal to what? a. The actual viscosity of the liquid b. The volume fraction of the slurry mixture occupied by the liquid c. The true drag force d. NOTA

a. The actual viscosity of the liquid

The empirical correction factor depends upon what? a. The actual viscosity of the liquid b. The volume fraction of the slurry mixture occupied by the liquid c. The higher effective viscosity of the mixture d. NOTA

b. The volume fraction of the slurry mixture occupied by the liquid

When the Reynolds number is less than 1, the settling is in the? a. Intermediate regime b. Newton's` Law regime c. Stokes` Law regime d. NOTA

c. Stokes` Law regime

When will the wall effect be exerted on the particle? a. When the settling is occurring at the diameter of the particle b. When the correction factor is equal to 1 c. When the diameter of the particle becomes appreciable with respect to the diameter of the container. d. NOTA

c. When the diameter of the particle becomes appreciable with respect to the diameter of the container.

What happens to the terminal velocity when the wall effect is exerted on the particle? a. It reduces b. It increases c. It remains the same d. NOTA

a. It reduces

The Spitzkasten classifier separates particles based on what principle? a. Size and density b. Color and shape c. Electrical conductivity d. Magnetic properties

a. Size and density

In which industry is the Spitzkasten classifier commonly used? a. Food processing b. Mining industry c. Pharmaceutical industry d. Textile industry

b. Mining industry

What is the advantage of using a Spitzkasten classifier? a. It can handle large volumes of material and is relatively inexpensive. b. It is effective only for separating very fine particles. c. It is not suitable for separating particles of different sizes and densities. d. It is complex and expensive to maintain

a. It can handle large volumes of material and is relatively inexpensive.

What is the limitation of a Spitzkasten classifier? a. It can effectively separate very fine and very large particles. b. It cannot be adjusted to accommodate different particle sizes. c. It may not be suitable for very fine particles. d. It is simple to operate and maintain.

c. It may not be suitable for very fine particles.

What is the other name for the sedimentation process called? a. Filtration b. Thickening c. Lixiviation d. Coagulation

b. Thickening

What is the main purpose of a sedimentation thickener in wastewater treatment? a. To add chemicals to the wastewater b. To separate solids from the liquid using gravity c. To change the pH of the wastewater d. To disinfect the wastewater

b. To separate solids from the liquid using gravity

What is the shape of a typical sedimentation thickener? a. Rectangular b. Cylindrical c. Triangular d. Spherical

b. Cylindrical

What is the advantage of using a sedimentation thickener? a. It is less effective for thickening thin sludges to more dense sludges. b. It can be less effective for larger particles due to screen blinding c. It is a simple and cost-effective method for thickening sludge. d. It is difficult to operate and maintain.

c. It is a simple and cost-effective method for thickening sludge.

What is the limitation of a sedimentation thickener? a. Overfeeding the thickener can lead to reduced efficiency. b. It is highly effective for separating smaller particles c. It is not suitable for industrial applications. d. It requires constant replacement of parts.

a. Overfeeding the thickener can lead to reduced efficiency.

In a laboratory set-up, what happens to the solids in the suspension after the sedimentation process? a. They are dissolved in the clarified water. b. They settle at the bottom of the tank. c. They remain suspended in the mixture. d. They are vaporized into the air.

b. They settle at the bottom of the tank.

Brownian motion is present if the particles are? a. quite big b. quite small c. NOTA d. All of the above

b. quite small

How does Brownian motion affect the settling of particles? a. It increases their settling speed. b. It may occur slowly or not at all c. It has no effect. d. It makes them settle in a straight line.

b. It may occur slowly or not at all

At what particle size (approximately) does Brownian motion become appreciable? a. 1 millimeter b. A few micrometers c. 1 centimeter d. 10 micrometers

b. A few micrometers

Which of the following methods can help reduce the effect of Brownian motion for very small particles? a. Increasing gravity b. Decreasing the density of the fluid c. Applying centrifugal force d. Adding salt to the solution

c. Applying centrifugal force

What is the term used for a particle falling under the action of gravity that will accelerate until the drag force balances gravitational force? a. Buoyancy b. Terminal velocity c. Viscosity d. Aerodynamic lift

b. Terminal velocity

What factors can cause fluctuations in the settling of particles? a. Only gravity b. Only particle size c. Vortex shedding and particle shape d. Temperature of the fluid

c. Vortex shedding and particle shape

Where did the drag crisis occur? a. at high Reynolds numbers b. it was not happening c. At lower Reynolds number when the free stream is turbulent. d. NOTA

c. At lower Reynolds number when the free stream is turbulent.

What is the random motion imparted to the particle by collisions between the molecules of the fluid surrounding the particle and particle? a. Terminal velocity b. Brownian Motion c. Gravity d. Sedimentation

b. Brownian Motion

Internal circulation inside the particle and particle deformation can occur when the particles are? a. Spherical Particle b. Non-rigid c. rigid d. None of the above

b. Non-rigid

In the turbulent Newton’s law region above a Reynolds number of about 1000 to 2.0 105, the drag coefficient is? a. 0.44 b. 0.54 c. 0.77 d. All of the above

a. 0.44

Helps in separating coal samples according to the difference in their respective specific gravities in a heavy liquid medium. a. Sink and Float method b. Differential Settling method c. Hindered Settling d. NOTA

a. Sink and Float method

Devices for the separation of solid particles into several fractions based upon their rates of flow or settling through fluids are known as _____ a. Sink and Float method b. Classifiers c. Differential Settling method d. Free Settling

b. Classifiers

Sink and float method is dependent on the sizes of the particles and depends only upon the relative densities of the two materials. This means liquid used must have densities greater than water, since most solid has high densities a. Both statements are true b. Both statements are false c. The first statement is true. The second statement is false d. The first statement is false. The second statement is true

d. The first statement is false. The second statement is true

Utilizes the difference in terminal velocities that can exist between substances of different densities a. Sink and Float method b. Differential Settling method c. Free Settling d. Batch Sedimentation

b. Differential Settling method

What is the disadvantage of the Differential Settling method a. the larger, light particles settle at the same rate as the smaller heavy ones and mixed fraction is obtained b. the smaller, light particles settle at the same rate as the larger heavy ones and mixed fraction is obtained. c. the larger, light particles do not settle at the same rate as the smaller heavy ones thus a mixed fraction is obtained. d. NOTA

a. the larger, light particles settle at the same rate as the smaller heavy ones and mixed fraction is obtained

In the Sink and Float method, what happens to the heavy and light material? a. the heavy material floats while the lighter material settles through the medium b. the heavy material sinks through the medium while the lighter material floats c. both settles through the medium d. both materials floats

b. the heavy material sinks through the medium while the lighter material floats

57. Use of Differential Settling method a. to know the thermal velocity b. to bring in the concept of equal-settling particles c. to settle each particle individually without interaction with neighboring particles d. NOTA

b. to bring in the concept of equal-settling particles

This method is also called heavy-fluid separation a. Differential Settling method b. Sink and Float method c. Free Settling d. Hindered Settling

b. Sink and Float method

In the sink and float method, both light and heavy materials settle through the same medium. This method also brings in the concept of the equal-settling method. a. Both statements are true b. Both statements are false c. The first statement is true. The second statement is false

b. Both statements are false

What is the advantage of the Sink and Float method? a. the separation depends only on the difference in the densities of the two substances and is independent of the particle size b. the separation depends on the similarities in the densities of the two substances and is dependent of the particle size c. the separation depends only on the difference in the densities of the two substances and is dependent of the particle size d. the separation depends only on the difference in the densities of the two substances and is independent of the particle size and shape

a. the separation depends only on the difference in the densities of the two substances and is independent of the particle size

The time given by dividing the vertical height of the chamber by the settling velocity must be ______ the residence time of air. a. less than b. more than c. equal to d. greater than or equal to

a. less than

Which of the following factors most significantly affects the settling velocity of particles in a batch sedimentation tank? a. tank size b. temperature of the suspension c. particle size and density difference between the particles and the liquid d. viscosity of the surrounding liquid

c. particle size and density difference between the particles and the liquid

Which of the following statements about the advantages of batch sedimentation is NOT true? a. it is a relatively simple and low-cost process b. it can handle a wide range of solid particle sizes and densities c. it can be easily scaled up or down for different capacities d. it is a continuous process, allowing for constant operation

d. it is a continuous process, allowing for constant operation

The main purpose of a primary settling tank in wastewater treatment is to: a. completely remove all suspended solids from the wastewater b. remove a significant portion of settleable organic matter and grit through gravity separation c. disintegrate and dissolve organic compounds in the wastewater d. neutralize the pH of the wastewater

b. remove a significant portion of settleable organic matter and grit through gravity separation

Which of the following applications is NOT well-suited for batch sedimentation? a. primary clarification of wastewater b. thickening of sludge before further processing c. continuous production of a chemical product d. recovery of valuable minerals from a slurry

c. continuous production of a chemical product

When designing a batch sedimentation tank, it's important to consider the strength and stability of the structure. What factor plays a crucial role in determining the required wall thickness? a. the desired color of the tank for aesthetic purposes b. the depth of the tank and the volume of liquid it will hold. c. the specific gravity of the material used for construction. d. the type of flocculant used in the sedimentation process

b. the depth of the tank and the volume of liquid it will hold.

Compared to some other wastewater treatment technologies, batch sedimentation offers the advantage of: a. requiring highly specialized equipment b. eliminating the need for any chemical addition to the wastewater c. being a relatively simple and low-tech process with minimal moving parts d. providing complete removal of all organic matter and pathogens

c. being a relatively simple and low-tech process with minimal moving parts

The overall efficiency of a batch sedimentation process can be limited by: a. the ability to continuously monitor and adjust operating parameters during operation b. incomplete removal of settled solids during the unloading stage, leading to solids carryover in the effluent c. the high cost of flocculants required to promote particle aggregation d. the need for highly skilled operators to manage the complex batch cycle

b. incomplete removal of settled solids during the unloading stage, leading to solids carryover in the effluent

Materials used for the construction of a batch sedimentation tank should be: a. lightweight and easily transportable b. chemically resistant to the wastewater being treated c. highly flexible to accommodate thermal expansion d. primarily focused on aesthetics and ease of cleaning

b. chemically resistant to the wastewater being treated

How does properly operating and maintaining a primary settling tank impact a wastewater treatment plant? a. increased operational costs and higher energy consumption b. the generation of a larger volume of sludge for disposal c. a higher risk of accidental spills and environmental contamination d. improved effluent quality and reduced downstream treatment burden

d. improved effluent quality and reduced downstream treatment burden

sedimentaion Flashcards

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