Which type of material is filter sand recommended to be composed of?

Filter sand is specifically recommended to be composed of siliceous material due to its physical and chemical properties, which make it ideal for facilitating the filtration process in water treatment systems. Siliceous sand is primarily made up of silica (SiO2), which is a durable and non-reactive material. This quality is essential for ensuring that filter media can effectively trap and retain suspended solids and other impurities without breaking down or leaching harmful substances into the water being treated.

The structure of siliceous materials provides adequate voids for water to flow through while still capturing particles, thus improving the overall quality of the filtered water. The angular shape of certain types of siliceous sands can also enhance filtration efficiency by providing more surface area for contaminants to adhere to.

In contrast, organic materials can break down over time and introduce additional contaminants into the water, clay materials can clog filters due to their fine particle size and plastic materials do not possess the required physical characteristics for effective filtration. Each of these alternative options does not fulfill the necessary criteria for maintaining clarity and cleanliness in water treatment applications.