What are the common types of granular media filters in the US?

Granular media filters are a key component in water treatment processes, specifically designed to remove suspended solids and contaminants from water. In the United States, the most common types of granular media filters are sand filters, dual media filters, and mixed media filters.

Sand filters are perhaps the simplest and most widely used, employing a bed of sand to capture particles from water as it passes through. The grains of sand create a barrier that physically filters out larger particles and adsorbs smaller ones, effectively purifying the water.

Dual media filters consist of two different layers of media, typically sand and a lighter material such as anthracite coal. This combination allows for better filtration efficiency; the lighter media sits atop the sand, creating a gradient that captures particles of varying sizes. This design promotes a more extended run time and decreased headloss, which enhances the filter's overall performance.

Mixed media filters utilize three or more types of media, including sand, anthracite, and sometimes garnet. By mixing various media types, these filters can capture a broader range of particle sizes, increasing the effectiveness of contaminants removal and extending the filter’s operational life.

While reverse osmosis and ultraviolet systems are important water treatment technologies, they do not fall under the category of granular media