Arrange the following biological treatment processes in descending order of their oxygen requirements:
1. Aerobic lagoons
2. Anaerobic digestion
3. Trickling filters
4. Facultative ponds
1
2, 4, 3, 1
2
3, 1, 4, 2
3
1, 3, 4, 2
4
4, 1, 3, 2
Arrange the following biological treatment processes in descending order of their oxygen requirements:
1. Aerobic lagoons
2. Anaerobic digestion
3. Trickling filters
4. Facultative ponds