Florida Wastewater Practice Test

If the coliform count fails to meet standards, and chlorine supply is not an issue, what could be the problem?

1. Low chlorine concentration

2. Short circuiting and low contact time

3. High organic matter in influent

4. Insufficient aeration

The correct answer is: Short circuiting and low contact time

When the coliform count fails to meet standards, and chlorine supply is confirmed to be adequate, one potential issue could be short circuiting and low contact time. Short circuiting occurs when the flow of water through a treatment system does not provide sufficient time for effective disinfection to occur. This means that the pathogens, including coliform bacteria, may not be exposed to the disinfectant (in this case, chlorine) for the necessary duration to ensure their reduction to acceptable levels. In disinfection processes, maintaining proper contact time is crucial for effective pathogen elimination. If water moves too quickly through the system without adequate contact time, the chlorine may not have enough opportunity to interact with and deactivate the coliform bacteria, leading to higher counts than acceptable. This issue highlights the importance of both appropriate flow dynamics in treatment systems and ensuring effective contact time in disinfection processes.