California Wastewater Treatment Operator Practice Exam

What is the purpose of disinfection in wastewater treatment?

1. Breakdown of organic matter

2. Removal of suspended solids

3. Inactivation of pathogenic bacteria

4. Neutralization of acidic pH

The correct answer is: Inactivation of pathogenic bacteria

The purpose of disinfection in wastewater treatment is primarily to inactivate pathogenic bacteria, viruses, and other harmful microorganisms that may pose a risk to public health and the environment. Effective disinfection reduces the transmission of waterborne diseases and ensures that treated wastewater can be safely released into the environment or reused for various purposes, such as irrigation or industrial processes. While other processes in wastewater treatment focus on different aspects—like breaking down organic matter or removing suspended solids—disinfection specifically targets the elimination or inactivation of pathogens. This step is critical because, even after physical and biological treatment, harmful bacteria and viruses may still be present in the effluent, threatening the health of humans and ecosystems. Disinfection methods commonly employed include chlorination, ultraviolet (UV) light treatment, and ozone treatment, each designed to ensure the safety of the treated water. The neutralization of acidic pH is related to balancing wastewater before treatment but is not a primary goal of disinfection.