Basic Wastewater Operator Practice Exam

Which chemical is often used for disinfection in wastewater treatment?

1. Sodium hydroxide

2. Calcium carbonate

3. Chlorine

4. Ammonium sulfate

The correct answer is: Chlorine

Chlorine is commonly used for disinfection in wastewater treatment because of its strong oxidizing properties, which effectively kill bacteria, viruses, and other pathogens present in the water. The use of chlorine helps to ensure that the treated water is safe for discharge into the environment or for reuse, thereby protecting public health and the ecosystem. Chlorination is a well-established process due to its efficiency, availability, and relatively low cost. In addition to its effectiveness as a disinfectant, chlorine can also help in the removal of organic compounds through oxidation. The residual chlorine that remains after disinfection can continue to provide protection against recontamination during storage or transport of treated wastewater. In contrast, the other chemicals listed serve different purposes. Sodium hydroxide is primarily used for pH adjustment, calcium carbonate is typically used for alkalinity control, and ammonium sulfate is primarily used as a nutrient source for biological processes. While these chemicals play important roles in wastewater treatment, they do not serve as disinfectants like chlorine does.