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Question #45420
The Question
During the secondary treatment of wastewater, an aeration tank receives an extreme, unregulated influx of organic effluent. This causes the Biochemical Oxygen Demand (BOD) to drastically exceed the mechanical aeration capacity. As the Dissolved Oxygen (DO) drops below a critical threshold, which of the following represents the most accurate systemic consequence?
Options
- A.
The 'flocs' will multiply exponentially to compensate for the high organic load, maximizing the release of CO2 and H2O.
- B.
Aerobic microbial populations will crash, shifting the decomposition process to anaerobic bacteria that produce CH4, H2S, and CO2.
- C.
The rate of mineralization will peak as facultative anaerobes utilize the remaining organic matter to form activated sludge.
- D.
Methanogenic archaea will utilize the remaining dissolved oxygen to rapidly ferment the organic matter into biogas.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Biochemical_Oxygen_Demand|Activated_Sludge|Aerobic_Respiration
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume that a higher organic load (more food) will always lead to increased microbial growth (flocs).
They fail to recognize DO as the absolute limiting factor in secondary treatment.
The trap tests the understanding of the ecological tipping point where DO depletion causes a metabolic switch from aerobic to anaerobic decomposition, fundamentally changing the chemical end-products and causing the failure of the aerobic flocculation process.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Chemical Coordination and Integration - Class 11 |
| Concept | Feedback Mechanism Loops |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |