Florida Wastewater Practice Test

What should you do if lab samples have settled to the bottom upon arrival?

1. Discard the samples

2. Mix them well

3. Heat the samples

4. Test the bottom layer only

The correct answer is: Mix them well

When lab samples have settled to the bottom upon arrival, the appropriate action is to mix them well. This is crucial because settling can lead to stratification, where different components of the sample separate based on density. Mixing ensures that the sample is homogenous, allowing for accurate testing results that reflect the true composition of the wastewater. Proper mixing helps to distribute any suspended solids or particulate matter throughout the sample, which can be essential for various tests, including those measuring chemical and biological properties. If the samples were simply tested without mixing, the results may be skewed and not represent the overall condition of the wastewater. The other options are not advisable because discarding the samples would waste potentially valuable data, heating might alter the chemical or biological properties of the sample, and testing only the bottom layer would not provide a complete picture of the sample's composition. Thus, ensuring a thorough mix is the best practice to maintain the integrity of the lab samples.