Tennessee Wastewater Operator Practice Exam

What effect does excessive solid accumulation in water have on its quality?

1. Improves clarity

2. Decreases available oxygen

3. Increases biological activity

4. Enhances nutrient levels

The correct answer is: Decreases available oxygen

Excessive solid accumulation in water can significantly decrease the available oxygen levels. When solids accumulate, they can serve as a substrate for microbial growth. As these organisms consume organic material, they utilize dissolved oxygen from the water column in their metabolic processes. This results in lower oxygen levels, which can be detrimental to aquatic life, particularly organisms that rely on oxygen for survival, such as fish and aerobic microorganisms. In contrast, while an increased load of solids might initially seem to enhance biological activity or nutrient levels, the resulting oxygen depletion can create an environment that is unsuitable for many forms of life. Clarity is unlikely to improve under these conditions, as the accumulation of solids typically leads to murkiness and reduced light penetration in the water. Thus, the decrease in available oxygen due to excessive solid accumulation is a critical and detrimental effect on water quality.