Which type of filtration is described as pressure filtration?

The correct answer is rapid filtration, which is considered a type of pressure filtration. In rapid filtration systems, water is passed through a filter medium under pressure, allowing for a faster flow rate compared to gravity filtration. This method efficiently removes suspended solids and can handle larger volumes of water in a shorter period.

Rapid filtration systems typically utilize a filter bed composed of materials such as sand or gravel, which traps particulates as water flows through. The pressurized mechanism enhances the process by forcing water through the filter, making it suitable for municipal water treatment plants where efficiency and speed are crucial to meet demand.

Other types of filtration, such as gravity filtration, operate based on gravitational forces rather than pressure. Gravity filtration relies on the natural flow of water downward through the filter medium, which is generally slower and less efficient for large scale operations. Membrane filtration utilizes a different concept, involving semi-permeable membranes to separate particles based on size, and is not specifically defined by pressure filtration alone. Sand filtration also typically functions under gravity, and while it can be pressurized, it is not synonymous with rapid filtration in contexts where these terms are commonly used in water treatment.