What is another term for a dual media filter?

A dual media filter is commonly referred to as a mixed media filter because it typically uses two different types of filter media to enhance the treatment process. This configuration usually consists of one type of media with a coarser grain, such as anthracite or sand, and another with finer grains, such as activated carbon or sand in a different size. The combination allows for more effective filtration, as the larger particles are captured first, while the finer media removes smaller particles and contaminants from the water more effectively.

The use of mixed media improves flow rates and extends the filter's lifespan by reducing the frequency of backwashing required. This choice enhances the overall efficiency of the filtration system, making it particularly suitable for treating potable water.

In contrast, the other options describe different types of filters that do not share the dual media aspect. A sand filter primarily uses only sand as its filtering media, a biological filter utilizes living organisms to break down contaminants, and an activated carbon filter focuses on absorbing organic compounds, chlorine, and other chemicals using activated carbon. Each of these has its unique purpose and media type, which distinguishes them from the dual media or mixed media filter system.