Basic Wastewater Operator Practice Exam

What is the primary use of chlorine in wastewater treatment?

1. Increase pH

2. Increase dissolved oxygen

3. Disinfection

4. Decrease solids

The correct answer is: Disinfection

Chlorine is primarily used in wastewater treatment for disinfection purposes. This process involves the application of chlorine to kill or inactivate harmful pathogens and microorganisms present in the wastewater. Disinfection is critical in ensuring that the treated water can be safely discharged into the environment or reused without posing health risks to humans or aquatic life. Chlorine works effectively against a broad spectrum of bacteria, viruses, and protozoa, making it a popular choice in many treatment facilities. It acts quickly and has a residual effect, meaning it can continue to disinfect even after the initial application. In contrast, increasing pH is typically accomplished using alkaline substances like lime, while increasing dissolved oxygen is managed through aeration methods, such as using air blowers or diffusers. Decreasing solids often involves sedimentation or filtration techniques rather than the use of chlorine. Thus, the unique role of chlorine as a disinfectant differentiates it from these other functions in wastewater treatment.