Correct Answer - Option 2 : aerobic suspended
Explanation:
Activated sludge process:
- The essential features of the activated sludge process are an aeration stage, solids-liquid separation following aeration, and a sludge recycle system.
- Wastewater after primary treatment enters an aeration tank where the organic matter is brought into intimate contact with the sludge from the secondary clarifier.
- It requires less space, does not produce obnoxious odor, and requires less time for wastewater treatment.
- It requires skilled supervision
Important point:
Followings are the classification of secondary treatment units:
|
Method
|
Contact Mechanism
|
Decomposition
|
|
Trickling filter
|
Attached growth
|
Aerobic
|
|
Rotating biological contactor
|
Attached growth
|
Aerobic
|
| Activated sludge process |
Suspended growth
|
Aerobic
|
|
Oxidation pond
|
Suspended growth
|
Aerobic
|
|
Septic tank
|
Suspended growth
|
Anaerobic
|
|
Imhoff tank
|
Suspended growth
|
Anaerobic
|
