Question

The periodicity, with which rapid gravity filters need cleaning is of the order of

• A. $ 1-2 \, \text{Years} $
• B. $ 10-15 \, \text{Days} $
• C. $ 1-3 \, \text{Months} $
• D. $ \checkmark \, 24-48 \, \text{Hours} $

Hint:

Remember: - Rapid gravity filters operate at high flow rates. - They require frequent cleaning (daily or every 2 days). - Slow sand filters, in contrast, may only need cleaning every few weeks or months.

Answer 1

The Correct Option is D

Step 1: Understand the operation of rapid gravity filters.
Rapid gravity filters are an essential component of water treatment systems. They remove suspended solids from water by passing it through a bed of sand or other granular media under gravity. Due to their high filtration rate, these filters get clogged relatively quickly and must be cleaned regularly through a process called backwashing.
Step 2: Evaluate each option.
$ 1-2 \, \text{Years} $: Incorrect; this is far too long for effective filter operation.
$ 10-15 \, \text{Days} $: Too infrequent; would lead to reduced efficiency and possible contamination.
$ 1-3 \, \text{Months} $: Still too long; not suitable for rapid gravity filters.
$ 24-48 \, \text{Hours} $: Correct; rapid gravity filters typically require cleaning every 24 to 48 hours to maintain filtration efficiency.
Step 3: Select the correct option.
Based on standard operational practices: $$ \boxed{24-48 \, \text{Hours}} $$