Match List I with List II
| LIST I | LIST II |
|---|---|
| A. Anaerobic sludge digestor | I. Secondary treatment |
| B. Primary sludge | II. Activated sludge |
| C. Change in BOD | III. Primary treatment |
| D. Bacterial flocs | IV. Biogas |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A-IV, B-III, C-I, D-II
A. Anaerobic sludge digestor — this matches IV. Biogas.
B. Primary sludge — this matches III. Primary treatment.
C. Change in BOD — this matches I. Secondary treatment. BOD falls as microbes use up organic matter.
D. Bacterial flocs — this matches II. Activated sludge.