Sand filtration

Sand filtration is a process in which the treatment of the water is realised by the ‘porous’ nature of a sand layer which traps particles present in water. Various other physical/ biological processes also take place in a sand filter which further strip the water of different substances (deferrisation, demanganisation, ammonium removal).

Sand filtration is frequently used in the treatment of groundwater to remove dissolved iron and manganese in the groundwater are oxidised by aeration and the flocs formed are subsequently trapped in the sand filter. After a certain period of time, the filter is saturated with particles and must be cleaned to prevent it from blocking up completely. The sand filters are cleaned by backwashing with air and/or water.

Sand filters can be a great pre filter for ultrafiltration modules and systems since it filtrates very accurate. A sand filter is not used to remove bacteria and virusses, therefore an ultrafilter should be installed downstream the sand filter.