Tennessee Wastewater Operator Practice Exam

What does ultraviolet disinfection primarily target?

1. Heavy metals

2. Solids in water

3. Pathogens

4. Organic nutrients

The correct answer is: Pathogens

Ultraviolet disinfection primarily targets pathogens, which include bacteria, viruses, protozoa, and other microorganisms. The mechanism of UV disinfection involves the exposure of these pathogens to ultraviolet light, which disrupts their DNA or RNA, preventing them from replicating and effectively inactivating them. This makes UV disinfection a highly effective method for reducing microbial contamination in water, ensuring it is safe for discharge or for reuse, particularly in wastewater treatment processes. In contrast, heavy metals, solids in water, and organic nutrients do not respond to UV light in the same way. Heavy metals require chemical treatments for removal, while solids are typically addressed through physical processes such as sedimentation or filtration. Organic nutrients may need biological treatment methods for reduction, such as aerobic or anaerobic digestion. Therefore, the focus of ultraviolet disinfection is specifically on eliminating these harmful microorganisms, making it a critical step in water treatment systems aimed at public health protection.