A common filter is the slow sand filter, having several layers of differently sized media.

A common filter is the slow sand filter, having several layers of differently sized media.

• A. It has only one layer
• B. It uses activated carbon
• C. True
• D. False

Answer: (D)

Slow sand filtration relies on a bed with multiple media layers: typically a coarse gravel base beneath a finer sand top. The gravel supports the bed and creates large pore spaces, while the sand layer traps smaller particles as water passes slowly through. This arrangement also supports a biologically active layer at the surface that helps remove organic matter and microorganisms, enhancing filtration. Activated carbon isn’t a defining feature of this type of filter. So the statement about slow sand filters having several layers of differently sized media is true.

Slow sand filtration relies on a bed with multiple media layers: typically a coarse gravel base beneath a finer sand top. The gravel supports the bed and creates large pore spaces, while the sand layer traps smaller particles as water passes slowly through. This arrangement also supports a biologically active layer at the surface that helps remove organic matter and microorganisms, enhancing filtration. Activated carbon isn’t a defining feature of this type of filter. So the statement about slow sand filters having several layers of differently sized media is true.