If an operator collects 200 ml samples from a lagoon's effluent every hour, what type of sample is created?

The scenario describes an operator collecting 200 ml samples every hour from a lagoon's effluent. This sampling method results in a composite sample, which combines multiple individual samples taken at different times. The purpose of a composite sample is to provide a more representative measurement of the effluent quality over a specified period, in this case, one hour.

Composite sampling is particularly useful in wastewater operations because it can help account for variations in effluent quality that may occur due to factors such as changes in flow or influent loading. By integrating the individual samples collected each hour, the operator obtains a broader perspective of the effluent's overall characteristics rather than just a snapshot at a single moment, which is what would occur with a grab sample.

In contrast, a grab sample involves taking a single sample at a specific point in time, and flow proportional sampling refers to a method where the sample volume is collected in proportion to the flow rate of the effluent. Proportional monitoring generally pertains to a broader set of practices that may not specifically refer to how samples are composed over time. Thus, the correct definition and method aligning with the described sampling process is that it is a composite sample.