Test: Types Of Screens And Aerators


10 Questions MCQ Test Environmental Engineering | Test: Types Of Screens And Aerators


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Attempt Test: Types Of Screens And Aerators | 10 questions in 25 minutes | Mock test for Chemical Engineering preparation | Free important questions MCQ to study Environmental Engineering for Chemical Engineering Exam | Download free PDF with solutions
QUESTION: 1

 Which process of water treatment is done to avoid floating debris, branches, trees or other large particles suspended in water?

Solution:

Explanation: Screens are used as a pretreatment process for purification of water to avoid large size suspended materials from water.

QUESTION: 2

What is the size of coarse screen used in pretreatment of water?

Solution:

Explanation: Coarse screens are used in the form of bars of 25mm diameter size and are spaced at 75 to 100mm centers.

QUESTION: 3

The coarse screen is inclined at _____ to facilitate the cleaning or raking.

Solution:

Explanation: The coarse screen is inclined at 450-600 so that they can be easily cleaned with a rake. Moreover, it reduces the flow velocity which also helps in cleaning the screen

QUESTION: 4

 The head loss through screen depends on

Solution:

Explanation: The head loss through the screen is given by, h=B (w/b) 4/3h1*sinx Where h=head loss, h1=approach velocity head, b=minimum width, x=angle of rack, B=shape factor. It also depends on the nature of their construction.

QUESTION: 5

The shape factor for circular rods in finding the head loss through the screen is _____

Solution:

Explanation: The shape factor rectangular bar with sharp edges is 2.42, for semicircular face is 1.83 and for circular rod is 1.79.

QUESTION: 6

 Identify the incorrect statement regarding aeration process.

Solution:

Explanation: Aeration reduces the carbon dioxide content and corrosiveness of water and hence, raises the pH value of water.

QUESTION: 7

The reduction of carbon dioxide by cascade aerators is in the range of

Solution:

Explanation:Cascade aerators are the gravity aerators in which water falls from 1-3m height such that it comes in contact with air and reduces carbon dioxide content to 50-60%.

QUESTION: 8

 In which type of aerator, the flow of water is divided into fine streams and small droplets?

Solution:

Explanation: In Cascade aerator, the flow of water is divided into fine streams and small droplets such that they come in contact with air in their trajectories and reduces CO2 by 70-90%.

QUESTION: 9

The elapsed time in gravity filter is 1sec. What is the height of fall in a single descent?

Solution:

Answer: b
Explanation: t = 1sec, g = 9.8
Elapsed time, t = (2h/g) 1/2 in a single descent.
Height of fall, H = t2g/2 = 1*1*9.8/2= 4.9m.

QUESTION: 10

 ______ are used in fine screen so that they do not get clogged up.

Solution:

Explanation: Automatic strainers are self cleaning devices which remove solids from the flowing liquid continuously and help in fine screen so that it do not get clogged up.

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