Where in the treatment plant is nitric acid most commonly used?

• A. In the influent system
• B. To clean the equipment
• C. In the laboratory
• D. In the well system

Answer: (C)

Nitric acid is mainly used in the lab for analytical chemistry tasks such as digesting samples and preparing reagents, as well as adjusting acidity for tests. This controlled, safety-focused setting is where the chemical is most needed and managed. In the influent system, acids or bases are used to adjust process pH, but nitric acid isn’t the typical choice because it adds nitrate to the water and can complicate analyses and corrosion control. Cleaning equipment usually relies on other acids like hydrochloric or sulfuric acids, which are better suited for removing mineral buildup without the same analytical implications. The well system focuses on source water handling and corrosion prevention rather than routine acid use. Therefore, the laboratory is where nitric acid is most commonly used in a treatment plant.