Wastewater New York State Practice Exam

How is the suspended solids concentration calculated from a plant influent composite sample?

1. By multiplying the crucible weight with the sample volume

2. By subtracting the weight of the empty crucible from the wet sample weight

3. By dividing the dry solids weight by the sample volume

4. By calculating the difference in weight as a ratio to the sample volume

The correct answer is: By calculating the difference in weight as a ratio to the sample volume

The correct answer is derived from understanding how to quantify suspended solids concentration in a wastewater sample accurately. When calculating suspended solids concentration from an influent composite sample, the key process involves determining the weight of the solids that remain after the sample has been filtered and dried. The effective method involves measuring the dry solids weight, which is obtained by taking the weight of the crucible containing the dried sample and subtracting the weight of the empty crucible. This gives the total weight of the solids contained in the sample. To find the concentration, this weight is then expressed as a ratio to the sample volume. This results in a concentration measured in units such as milligrams per liter (mg/L), which is a standard way to report suspended solids concentrations in wastewater treatment. The method emphasizes that concentration is fundamentally about understanding how much solid material exists in a given volume of liquid. By dividing the difference in weight (the weight of the dry solids) by the sample volume, one can accurately express how concentrated the suspended solids are in the influent stream. This approach provides a clear and quantitative measure of influent quality, which is essential for effective wastewater treatment management.