Texas Wastewater Class B Practice Exam

What is the expected BOD removal percentage typically achieved in the Activated Sludge Process?

1. 50 to 60%

2. 70 to 80%

3. 90 to 99%

4. 100%

The correct answer is: 90 to 99%

The correct answer is that the expected BOD removal percentage typically achieved in the Activated Sludge Process falls within the range of 70 to 90%. The Activated Sludge Process is designed to effectively treat wastewater by reducing Biological Oxygen Demand (BOD), primarily through the action of microorganisms that break down organic matter. While some advanced treatment methods can achieve very high removal percentages, such as 90 to 99%, stating it as the typical expected outcome may be misleading, as operational conditions, loading rates, and specific system configurations can influence actual performance. Variability in these factors means that while exceptional cases exist, the standard performance generally ranges closer to 70 to 90%. Complete removal, denoted by a percentage of 100%, is typically not achievable in practical scenarios due to operational limitations and residual organic matter.