Waterguide - Sand and silex
General description
Sand (silica) is the oldest filter material found in nature due to its many different forms (sand, silex, gravel). Sand is still widely used to treat communal water in very large open, heavy-duty filters, in swimming pool filters and in pressure filters for treating groundwater. For the filtration of groundwater, filtration using sand was replaced with other filtration methods with better advantages (e.g. faster flow rate, better filtrate quality, lower tare weight, etc.).
Sand can be found everywhere in nature, even washed and sieved. The quality varies from one supplier to the next.
A sand filter that is under pressure always contains different types of sand layers. At the top there is relatively fine sand and coarse gravel as a protective layer. In between these layers it is common to use two other grain sizes.
Physical properties
Colour Brown/yellowish
Bulk density 1.5 – 1.7 kg/l
Particle size There are lots of different types of fine to coarse gravel or sand
Application areas
The sand and silex filter material can be used to remove the following substances:
- Sediment
- Iron
- Manganese