The Air binding problem in a rapid gravity filter is because of the i. negative head ii. increase of water temperature as it passes through the filter bed iii. release of oxygen by algae
- AOnly (i)
- B(i) and (ii)
- C(ii) and (iii)
- D(i), (ii) and (iii)Correct
Solution
Concept
Air binding
Step-by-step solution
1. Negative head makes dissolved air come out of solution. 2. Warming of water reduces gas solubility. 3. Algae release oxygen in the filter bed. 4. All three cause air binding.
Explanation
All three release air into the bed.
Why the other options are wrong
Other options omit a cause.
Correct answer: D) (i), (ii) and (iii)