Consider the following statement. i. Slow sand filter is not flexible in variation in demand ii. The rapid sand filter is flexible in fluctuations in demand iii. The method of cleaning of a slow sand filter involves agitation and back-washing Which of the above statement is/are correct?

Cleaning is done by (i) Scraping and removal in filters slow sand (ii) Back washing in slow sand filters (iii) Scraping and removal in filters rapid sand (iv) Back washing in rapid sand filtersThe correct answer is

A

(i) and (ii)

B

(ii) and (iii)

C

(i) and (iv)

D

(ii) and (iv)

Cleaning is done by
(i) Scraping and removal in filters slow sand
(ii) Back washing in slow sand filters
(iii) Scraping and removal in filters rapid sand
(iv) Back washing in rapid sand filters
The correct answer is

A

(i) and (ii)

B

(ii) and (iii)

C

(i) and (iv)

D

(ii) and (iv)

Consider the following statement. i. The penetration of suspended matter is deep in the slow sand filter ii. The penetration of suspended matter is superficial in the rapid sand filter iii. Coagulation is not required in the slow sand filter Which of the above statement is/are correct?

A

Only iii

B

i, ii

C

i, ii, iii

D

ii, iii

Consider the following statement. i. The slow sand filter is not efficient in removing turbidity ii. The slow sand filter has a high initial cost iii. Skilled supervision is required in slow sand filter Which of the above statement is/are correct?

A

Only iii

B

i, ii

C

i, ii, iii

D

ii, iii

Which of the following statements are correct pertaining to the value of uniformity coefficient Cu for filter sand? (1) For slow sand filters, Cu = 1.8 to 2.5 (2) For rapid sand filters, Cu = 1.3 to 1.7 (3) For slow sand filters, Cu = 1.3 to 1.7 (4) For rapid sand filters, Cu = 1.8 to 2.5

A

2 and 3

B

1 and 4

C

3 and 4

D

1 and 2

Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters.Reason R: The sand used in slow sand filters is finer than that in rapid sand filtersSelect your answer based on the coding system given below:

A

Both A and R is true and R is the correct explanation of A

B

Both A and R is true but R is not the correct explanation of A

C

A is true but R is false

D

A is false but R is true

Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters.
Reason R: The sand used in slow sand filters is finer than that in rapid sand filters
Select your answer based on the coding system given below:

A

Both A and R is true and R is the correct explanation of A

B

Both A and R is true but R is not the correct explanation of A

C

A is true but R is false

D

A is false but R is true

Consider the following statements in respect of slow sand filter and rapid sand filter: 1. The two filters differ in respect of the standards regarding the non-uniformity of the sand used in their filtering media. 2. The two filters do not differ in respect of the effective size of the sand used in them. 3. The two filters differ in respect of their respective under-drainage system. 4. The two filters differ in respect of their respective rate of filtration. Which of the above statements are correct?

A

1, 2 and 3

B

1, 2 and 4

C

2, 3 and 4

D

1, 3 and 4

The following are certain operating problems of a rapid sand filter: 1. Sand depth should never be depleted by more than 10 cm. 2. Air binding results due to development of negative head and formation of air bubbles in the filter sand. 3. Water softening with lime-soda leads to incrustation of sand. 4. Bumping of filter bed is caused due to negative head. Which of the above statements are correct?

A

1, 2 and 4 only

B

1, 2 and 3 only

C

3 and 4 only

D

1, 2, 3 and 4

The period of cleaning of a slow sand filter is ______ than rapid sand filter.

A

Smaller

B

Larger

C

Slightly smaller

D

Slightly larger

Consider the following statement. i. Slow sand filter is not flexible in variation in demand ii. The rapid sand filter is flexible in fluctuations in demand iii. The method of cleaning of a slow sand filter involves agitation and back-washing Which of the above statement is/are correct?

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