Tennessee Wastewater Operator Practice Exam

What type of activated sludge plant can handle a high organic shock load?

1. Step feed

2. Continuous flow

3. Suspended growth

4. Extended aeration

The correct answer is: Step feed

The step feed activated sludge process is specifically designed to effectively handle high organic shock loads. This is achieved by feeding wastewater into the treatment system at multiple points along the reactor rather than just one. By introducing the wastewater in steps, the process allows for more controlled treatment and can mitigate the effects of sudden increases in organic matter. This approach prevents the system from being overwhelmed by a sudden surge of pollutants, as smaller amounts of wastewater can be treated in stages. As a result, it develops a more stable microbial population that can respond to varying load conditions effectively. In contrast, other types of activated sludge processes may not be as adept at managing such fluctuations. Continuous flow systems typically provide a steady, uniform input, which might not cope well under sudden load increases. Suspended growth processes, while common, rely on the mixed liquor to buffer against shock loads, which may not be sufficient under extreme conditions. Extended aeration systems are designed for lengthier treatment times and lower organic load scenarios, making them less suitable for sudden high organic loads. Thus, the configuration of the step feed process, with its ability to stagger the input of wastewater, makes it particularly robust in managing high organic shock loads efficiently.