Wastewater New York State Practice Exam

Which activated sludge process can handle shock loads of dairy waste most effectively?

1. Plug flow

2. Sequencing batch reactor

3. Step feed

4. Extended aeration

The correct answer is: Step feed

The effectiveness of the step feed activated sludge process in handling shock loads of dairy waste stems from its design and operational characteristics. This process allows for the gradual introduction of influent into multiple points in the aeration basin, rather than a single point. By splitting the flow of incoming waste, step feed helps mitigate the impacts of sudden increases in organic load, such as those typical with dairy wastes. When dairy waste is introduced, it often contains high levels of fats, proteins, and other organic materials that can disrupt microbial populations if added all at once. The step feed method allows operators to tailor the aeration basin's response to these shock loads, distributing the pollutant load over time and across different zones within the basin. This flexibility enables the system to maintain optimal conditions for microbial activity, which is crucial for effective treatment. Additionally, the step feed process can enhance the overall treatment efficiency, as it encourages the growth of a diverse microbial community that can acclimatize to varying substrate concentrations. This is particularly important in dealing with the variability often associated with dairy waste. In contrast, other processes such as plug flow, sequencing batch reactors, and extended aeration may not offer the same level of adaptability when faced with rapid changes in waste loads. Each of those methods