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Difficulty: MediumDrawing Logical Conclusions

Municipal water filtration plants utilize powdered activated carbon to absorb organic pollutants before water reaches the primary sand filters. While effective, excess carbon particles can clog the sand filter pores if contact basin retention times drop below twenty minutes. To prevent filter clogging during high-demand surges when retention times fall to fifteen minutes, technicians must activate secondary coagulation aids that bind free carbon particles into heavy clumps. Yesterday morning, a sudden demand spike shortened retention times to twelve minutes, but secondary coagulation pumps were shut down for scheduled maintenance.

Based on the passage, which of the following is the most logical conclusion regarding yesterday's filtration process?

  1. A
    The municipal water supply required immediate boil-water notices due to widespread bacterial contamination.
  2. The primary sand filters were vulnerable to clogging by uncoagulated carbon particles.Answer
  3. C
    Powdered activated carbon completely ceased absorbing organic pollutants upon entering the contact basin.
  4. D
    Technicians artificially extended the contact basin retention time above twenty minutes to protect the offline pumps.

Answer

The primary sand filters were vulnerable to clogging by uncoagulated carbon particles.
The passage establishes two key premises: retention times under twenty minutes cause carbon to clog sand filters, and secondary coagulation aids are required to prevent this clogging when retention times are shortened. Because the retention time dropped to twelve minutes and the coagulation pumps were offline for maintenance, the system lacked the safeguard needed to stop carbon from clogging the sand filters.

Step-by-Step Solution

1
Identify the cause-and-effect conditions stated in the passage.
Unbound carbon particles clog sand filter pores whenever retention time drops below twenty minutes, unless secondary coagulation aids are active.
Establishing the rules governing filter operation is necessary to evaluate the outcome of specific operating conditions.
2
Evaluate the specific events that occurred yesterday.
Retention time dropped to twelve minutes (well below twenty minutes), and secondary coagulation pumps were offline.
Matching the actual events against the established rules reveals which safeguards failed.
3
Deduce the logical outcome from the combination of events.
Without active coagulation pumps to bind the carbon particles during a sub-twenty-minute retention period, the primary sand filters faced direct risk of clogging.
Synthesizing the constraints yields a strictly supported deduction about filter vulnerability.

Key Concept

Synthesizing multiple conditional constraints to deduce an unstated operational outcome.
Estimated Time:1m 0s
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Drawing Logical Conclusions

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