Post-DAF Oil and Grease Characterization and Filtration Study

A laboratory is required to characterize oil and grease in a post-dissolved air flotation, or post-DAF, process-water sample.

A previous analysis reported an oil and grease concentration of 31.2 mg/L. Additional testing is needed to better understand whether the reported concentration is associated primarily with free oil, dispersed or emulsified oil, filterable material, dissolved organic compounds, or potential analytical interferences.

The requested scope includes:

1. Analyze the original, unfiltered sample for oil and grease.
2. Filter a representative portion of the sample through a 1-micron filter.
3. Reanalyze the filtered sample for oil and grease using the same analytical method.
4. Compare the filtered and unfiltered results and provide a technical interpretation of the difference.
5. Recommend appropriate supplementary testing that may help distinguish free, dispersed, emulsified, and dissolved hydrocarbon-related material.

The laboratory should explain the limitations of the proposed oil and grease method, including whether it can directly determine the percentage of free, dissolved, or emulsified oil. Suggested complementary analyses may be included where technically appropriate.

The final report should document the analytical method, filtration procedure, detection limits, quality-control results, observations, and any factors that may affect interpretation. The objective is to determine whether the reported oil and grease concentration is predominantly filterable or remains present after 1-micron filtration.