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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? 

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?  Correct Answer 1, 3 and 4

Concept:

The comparison of Slow Sand and Rapid sand filters with respect to concerning parameters are briefed in the following table:

Characteristics

Slow Sand Filters

Rapid Sand Filters

The effective size of filtering sand

The effective size of the filter sand ranges between 0.2 to 0.4 mm.

The effective size of the filter sand ranges between 0.35 to 0.55 mm.

Uniformity coefficient of filtering sand

The uniformity coefficient of the filter sand ranges between 1.8 to 2.5 or 3.0.

The uniformity coefficient of the filter sand ranges between 1.2 to 1.8.

Under drainage system

Laid in order to receive only filtered water. Generally, open jointed pipes or drains covered with blocks is be used

Laid in order to receive filtered water and also to pass water for backwashing. Generally, perforated pipe laterals or diffuser plate bottom are used.

Rate of filtration

 

Low, typically ranges 100 to 200 liters per hour per sq. m of filter area.

High, typically ranges 3000 to 6000 liters per hour per sq. m of filter area.

 

∴ Hence, statement 2 is incorrect, and the rest are correct.

Related Questions

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
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:
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
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:
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
As compared to rapid sand filters, slow sand filters give (i) Slower filtration rate (ii) Higher filtration rate (iii) Lesser efficiency in removal of bacteria (iv) Higher efficiency in removal of bacteria The correct answer is
As compared to rapid sand filters, slow sand filters give
(i) Slower filtration rate
(ii) Higher filtration rate
(iii) Lesser efficiency in removal of bacteria
(iv) Higher efficiency in removal of bacteria
The correct answer is
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?
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?
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?