What is a key feature of diatomaceous earth pressure filters during operation?

A key feature of diatomaceous earth pressure filters during operation is that body feed is added to maintain filtration. Diatomaceous earth is a porous medium made from the fossilized remains of diatoms, which are microscopic algae. During the filtration process, the diatomaceous earth needs to be kept in suspension and properly distributed across the filter surface. Adding body feed, which is essentially a mixture of diatomaceous earth and water, enhances the filtering capacity and helps in creating a stable layer of DE on the filter elements. This ensures that the filter operates effectively, providing clear water by capturing particles and impurities while extending the filter run time.

In contrast, other options do not accurately describe the operational characteristics of diatomaceous earth filters. For example, while some filtration systems may utilize gravity for flow, diatomaceous earth pressure filters rely on pressure to push water through the filter media, which is a crucial aspect of their operation. Insulation is not a standard requirement for these filters as they do not generally involve temperature-sensitive processes. Lastly, the media used in diatomaceous earth filters does require initial coating with the DE to establish efficient filtration; therefore, the claim that the media does not need coating is not accurate for this specific type of filter.