Wastewater Treatment Operator Certification Practice Test

What could happen if the sludge line is isolated by closing the valves on each end for several days?

1. It could result in water hammer

2. Cavitation

3. Increased internal pressure could cause line failure

4. Aerobic conditions would lead to excessive growth of Zooglea

The correct answer is: Increased internal pressure could cause line failure

Isolating the sludge line by closing the valves on each end for several days can lead to increased internal pressure within the line. When the flow of sludge is stopped, the material that remains can continue to produce gases as a result of anaerobic decomposition. These gases build up pressure within the closed system. If the internal pressure exceeds the line's design limits, it can lead to a failure of the line, potentially causing leaks or ruptures. Therefore, increased internal pressure causing line failure is a critical concern in wastewater management. In contrast, other options, such as water hammer and cavitation, refer to different hydraulic phenomena often associated with rapid changes in fluid flow or pressure, which might not directly apply to a stagnated sludge line situation. Aerobic conditions and excessive growth of Zooglea could also occur, but the isolation primarily results in dangerous accumulations of pressure, making that the most critical issue to address.