Oil and grease samples are what type of samples?

• A. Grab samples
• B. Composite samples
• C. Random samples
• D. Bulk samples

Answer: (A)

Oil and grease levels in wastewater can vary a lot over short time periods as flows change or when certain discharges occur. Because you want to know the actual condition at a specific moment, a grab sample is used to capture an instantaneous concentration. If you were to use a composite sample, the spikes would be averaged out, potentially hiding peak discharges and giving a misleading picture of the oil and grease burden. Bulk sampling is for large solids or bulk material collection, and random sampling isn’t the standard approach for this parameter, which is typically measured from a single, point-in-time sample.