Tennessee Wastewater Operator Practice Exam

Before diluting a BOD sample, what temperature adjustment is necessary?

1. 15 degrees C

2. 20 degrees C

3. 25 degrees C

4. 30 degrees C

The correct answer is: 20 degrees C

Before diluting a Biological Oxygen Demand (BOD) sample, it is essential to adjust the temperature to a specific standard to ensure consistent and reliable results during the testing process. The standard temperature for BOD analysis is typically set at 20 degrees Celsius. This temperature is established because it closely mimics environmental conditions that affect microbial activity, allowing for an accurate assessment of the oxygen demand exerted by bacteria within the sample. When BOD samples are collected, they could be at varying temperatures, which might impact the metabolic rates of the microorganisms involved in the testing. By adjusting the temperature to 20 degrees Celsius before dilution, operators can standardize the testing conditions and minimize fluctuations in microbial activity that could lead to inaccurate readings of the BOD level. Choosing a different temperature, such as 15, 25, or 30 degrees Celsius, would not align with these standards and could lead to discrepancies in the BOD measurements, affecting the reliability of the test results and possibly resulting in compliance issues for wastewater treatment facilities. Standardizing at 20 degrees Celsius helps ensure that tests are comparable and more reflective of actual environmental conditions in wastewater treatment.