Tennessee Wastewater Operator Practice Exam

One reason a wastewater treatment plant may prefer UV over chlorine for disinfection is:

1. Lower cost

2. Faster disinfection time

3. Concern over chlorine safety

4. More effective on bacteria

The correct answer is: Concern over chlorine safety

Choosing UV disinfection over chlorine for a wastewater treatment plant is often influenced by concerns over the safety of chlorine. Chlorine can produce harmful disinfection by-products (DBPs) that have significant health and environmental implications. When chlorine is used to disinfect, it can react with organic matter present in wastewater to form these potentially harmful compounds, which are regulated due to their associated risks. In contrast, UV disinfection does not introduce any chemicals into the water, thus eliminating the risk of creating DBPs. It effectively inactivates a wide range of pathogens without altering the chemical composition of the water, making it a safer option in terms of public health and environmental impact. While there may be other considerations such as costs or speed, the primary reason many plants lean towards UV is to mitigate the safety concerns associated with chlorine usage.