Ontario Operator-in-Training (OIT) Practice Exam

Which method is commonly used for disinfecting wastewater?

1. UV treatment

2. Filtration

3. Gravity settling

4. Flocculation

The correct answer is: UV treatment

The method commonly used for disinfecting wastewater is UV treatment. This process employs ultraviolet light to kill or inactivate harmful microorganisms present in the water without the use of chemicals. UV treatment is effective because it disrupts the DNA of bacteria, viruses, and protozoa, rendering them incapable of reproduction and infection. This method has several advantages, including leaving no chemical residues in the treated water, which is essential for compliance with environmental regulations and safety standards. Furthermore, UV treatment can be used in various types of wastewater treatment facilities, making it a versatile option. In contrast, filtration primarily deals with the physical removal of particles and does not directly disinfect the water. Gravity settling is a separation technique used to remove suspended solids by allowing them to settle at the bottom, while flocculation involves the aggregation of particles into larger flocs for easier removal; neither process specifically targets pathogen inactivation. Therefore, UV treatment stands out as the prominent method for disinfection in wastewater management.