Question 31 : When the fineness of sand increases
1. The bacterial efficiency increases
2. The rate of filtration increases
3. The rate of filtration first decrease, then increase
4. The bacterial efficiency remains constant
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Question 32 : Which of the following statement is wrong regarding Anthracite?
1. It requires less water
2. It is less inert to caustic solutions than sand
3. It is more costly per tonne than sand
4. It is used in industrial filters.
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Question 33 : The loss of head during cleaning operation of a rapid sand filter is
1. 15-30cm
2. 1-5cm
3. 10-20cm
4. 10-25cm
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Question 34 : State whether the following statement is true or false.
Schmutzdecke acts as an extremely fine meshed straining mat.
1. True
2. False
3.
4.
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Question 35 : ______ are formed in filters due to insufficient washing of sand grains.
1. Sand boils
2. Mud balls
3. Clogging
4. Bubbles
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Question 36 : What is the specific gravity of Anthracite used in a dual media filter?
1. 1
2. 1.4
3. 2.4
4. 4.2
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Question 37 : The under drainage system in pressure consists of
1. Central drains connected to lateral drain
2. Wheeler system
3. Wagner system
4. Pipe grids, false bottom
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Question 38 : Consider the following statements regarding pressure filter
1. It is easy to inspect the under drainage system
2. It is not possible to provide time for chlorination in direct supply from it
3. It is not possible to observe the degree of back washing and the agitation process
Which of the above statement is correct?
1. 1 only
2. 2, 3
3. 1, 2, 3
4. 1, 3
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Question 39 : Which type of problem is caused in filter due to accumulation of solids on the top surface of filter media?
1. Clogging
2. Air binding
3. Sand incrustation
4. Sand leakage
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Question 40 : The value of uniformity coefficient for uniformly graded sand is ______
1. 0
2. 1
3. 10
4. 100
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