Tennessee Wastewater Operator Practice Exam

For BOD samples, what is the minimum depletion in mg/L required for a valid test?

1. 1.0 mg/L

2. 2.0 mg/L

3. 3.0 mg/L

4. 4.0 mg/L

The correct answer is: 2.0 mg/L

The minimum depletion of 2.0 mg/L for a valid BOD (Biochemical Oxygen Demand) test is essential because it ensures that the sample contains sufficient organic matter to accurately assess the amount of oxygen consumed by microorganisms during the incubation period. If the depletion is too low, it may indicate that there wasn't enough biodegradable material in the sample to support microbial activity or that the sample wasn't representative of the wastewater's organic load. In wastewater treatment, BOD is a crucial parameter as it helps determine the amount of oxygen that will be required by microorganisms to break down organic matter present in the water. A depletion of less than 2.0 mg/L could lead to unreliable or inconclusive test results, as it may not reflect the true organic pollution level present in the sample being tested. Thus, maintaining this threshold is vital for ensuring the integrity and accuracy of BOD measurements in wastewater analysis.