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Question #46583
The Question
During the secondary treatment of sewage, an aeration tank experiences a temperature spike and is colonized by an invasive, heat-tolerant aerobic bacterium that does not associate with fungal filaments. It rapidly outcompetes the native microbial flora. Based on the principles of microbial ecology and wastewater treatment, which of the following is the most likely consequence of this ecological shift?
Options
- A.
The Biological Oxygen Demand (BOD) of the effluent will rapidly drop to zero due to the enhanced aerobic respiration of the highly competitive invasive species.
- B.
The sedimentation process in the settling tank will fail, preventing the formation of activated sludge and leading to the discharge of high-BOD effluent.
- C.
The invasive bacteria will immediately shift to anaerobic respiration, prematurely increasing biogas production within the aeration tank.
- D.
The primary effluent will bypass the secondary treatment phase entirely and directly enter the anaerobic sludge digester.
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 Inoculum|Alien Species Invasion Impacts|Thermal Tolerance Ranges
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often equate 'highly competitive aerobic bacteria' with 'efficient BOD reduction'.
The trap lies in forgetting NCERT's emphasis on the structural necessity of 'flocs' (bacteria + fungi).
Even if an invasive species respires aerobically, its inability to form sedimentable flocs destroys the mechanical separation phase in the settling tank, leading to high BOD in the final effluent.
This tests the synthesis of Microbes in Human Welfare with Population Ecology (Competitive Exclusion).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Microbes in Human Welfare - Class 12 |
| Concept | Activated Sludge Inoculum |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |