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Question #45919
The Question
During the secondary treatment of sewage, primary effluent is passed into large aeration tanks where it is constantly agitated. If a sudden influx of industrial waste containing high concentrations of heavy metal toxins enters this tank, which of the following represents the most accurate physiological consequence?
Options
- A.
Vigorous growth of flocs is stimulated to bioaccumulate the toxins, leading to a rapid depletion of dissolved oxygen and a decrease in effluent BOD.
- B.
Aerobic heterotrophic microbes are inhibited or killed, halting the complete oxidation of organic matter and causing a sudden surge in the BOD of the effluent.
- C.
The heavy metals act as competitive inhibitors for methanogens, preventing biogas production in the aeration tank and increasing BOD.
- D.
The biological flocs immediately switch to anaerobic fermentation, utilizing the heavy metals as terminal electron acceptors to maintain BOD reduction.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Primary vs Secondary Sewage Treatment|Terminal Electron Acceptor|Activated Sludge
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Understanding that BOD reduction is strictly dependent on the viability and active respiration of aerobic flocs.
Location Trap: Students often confuse the microbial populations and processes of the aeration tank (aerobic heterotrophs) with those of the anaerobic sludge digester (anaerobic methanogens).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Respiration in Plants - Class 11 |
| Concept | Terminal Electron Acceptor |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |