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A facultative pond system is employed for wastewater treatment. Which of the following statements is/are true:

1. The dissolved oxygen concentration will be high during daytime compared to night-time
2. The pH will be high during daytime compared to night-time
3. The dissolved oxygen concentration will be low during daytime compared to night-time
4. The pH will be low during daytime compared to night-time

Correct answer: The dissolved oxygen concentration will be high during daytime compared to night-time

Solution

During the daytime, photosynthetic activity by aquatic plants and algae increases, leading to higher levels of dissolved oxygen in the water, while at night, respiration processes dominate, causing oxygen levels to drop.

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