Tennessee Wastewater Operator Practice Exam

Why are nutrients in discharged treated wastewater a concern for water quality?

1. It could contain nutrients that promote excess algae growth

2. It could increase water salinity levels

3. It can reduce the pH of the water

4. It could introduce heavy metals into the water

The correct answer is: It could contain nutrients that promote excess algae growth

The presence of nutrients in discharged treated wastewater is a significant concern for water quality primarily because these nutrients can stimulate excess algae growth, a phenomenon known as eutrophication. Nutrients, particularly nitrogen and phosphorus, serve as fertilizers in aquatic environments. When wastewater containing these nutrients is discharged into water bodies, it can lead to algal blooms. These algal blooms can have various detrimental effects on water quality and the ecosystem. They can reduce sunlight penetration in the water, harming aquatic plants, and when the algae die, their decomposition depletes oxygen levels in the water, which can lead to fish kills and the disruption of aquatic life. Additionally, some algae can produce toxins that are harmful to aquatic organisms and humans alike. In contrast, while increased salinity, reduced pH, or the introduction of heavy metals can also negatively impact water quality, they do not relate directly to the nutrient-induced growth of algae, making nutrients a more immediate concern in the context of wastewater discharge.