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Question #46569
The Question
A standing water body heavily invaded by the alien species Eichhornia crassipes experiences massive weed mortality and decomposition. If this water is directly channeled into a standard Sewage Treatment Plant (STP), which of the following accurately describes the physiological impact on the treatment process?
Options
- A.
The primary treatment fails because sequential filtration and sedimentation cannot process the sudden spike in Biochemical Oxygen Demand (BOD).
- B.
The aeration tank in the secondary treatment becomes overloaded, causing a rapid depletion of dissolved oxygen and subsequent degradation of aerobic microbial flocs.
- C.
The anaerobic sludge digester experiences a sudden spike in aerobic bacterial growth due to the nutrient-rich leachate, inhibiting biogas production.
- D.
The secondary treatment efficiency increases as the high nutrient load stimulates rapid multiplication of aerobic microbes without requiring mechanical agitation.
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
Activated Sludge|BOD|Eichhornia crassipes
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating the ecological impact of an invasive species (high BOD/low DO from Eichhornia) with the physiological constraints of secondary sewage treatment.
Common Misconception: Students often assume 'more nutrients = better microbial growth' (Option D), failing to recognize that in an aeration tank, Dissolved Oxygen is the limiting factor.
If the BOD load exceeds the aeration capacity, the F/M (Food to Microorganism) ratio is disrupted, the system turns anaerobic, and the essential aerobic flocs die.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Microbes in Human Welfare - Class 12 |
| Concept | Primary vs Secondary Sewage Treatment |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |