Which of the following filter media is considered a depth filter?

The choice of paper as a depth filter media is appropriate because depth filters operate by trapping particulates within the thickness of the filter material rather than just on the surface. Paper, being composed of fibers that create a complex network, allows for a three-dimensional matrix that captures and retains particles throughout its depth as fluid passes through. This characteristic enables depth filters to handle larger volumes of fluid and maintain effectiveness over time, as contaminants can be held within the material rather than clogging the surface.

In contrast, media such as metal screens and nonmetal disks are typically classified as surface filters. They primarily capture particles on their surfaces, which can lead to quicker clogging and reduced filtration effectiveness when faced with dirty or particulate-laden fluids. Sintered metal powder, while it can provide some depth filtering capabilities due to its porous nature, is often more recognized for its surface filtration properties as well, depending on its construction and application. Thus, paper stands out as the most suitable example of a true depth filter among the options presented.