Florida Wastewater Practice Test

What effect does a decrease in temperature have on disinfection processes?

1. It reduces the need for contact time

2. It requires longer contact time

3. It enhances the effectiveness of disinfectants

4. It has no effect on disinfection

The correct answer is: It requires longer contact time

A decrease in temperature has a significant impact on the efficiency of disinfection processes, specifically requiring longer contact time for disinfectants to achieve the desired level of microbial inactivation. At lower temperatures, the kinetic energy of the disinfecting agents and microorganisms is reduced, which can slow down the reaction rates between them. Consequently, the chemical reactions that lead to disinfection are less effective, since the activity and movement of particles are diminished. Therefore, to compensate for the reduced efficiency at lower temperatures, it becomes necessary to increase the contact time between the disinfectant and the pathogens. This adjustment ensures that adequate exposure occurs for the disinfectants to effectively eliminate or inactivate harmful microorganisms in the wastewater treatment process. Additionally, many disinfectants have optimal efficacy at specific temperature ranges, meaning that when temperatures drop below those ranges, their disinfecting power is noticeably diminished.