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The filter sand, consisting of 99.5% SiO2, is extremely low in trace metals and polycyclic aromatic hydrocarbons. This makes our filter sand the best sand available for monitoring well systems.
In water treatment, granular filtration is a process where water flows through granular material (often sand) while suspended solids (sand, clay, iron and aluminum flocs) are retained, substances are biochemically decomposed and pathogenic microorganisms (bacteria, viruses, protozoa) are removed.
====Granular media, rapid rate filters and filter media====[[Image:granular high density carbon.jpg|thumb|right|250px200px|Granular, high-density carbon.]][[Image:filter sand.jpg|thumb|right|250px200px|Filter sand, supplied in bags and pallet packages. It consists of 99.5% SiO2 and is extremely low in trace metals and polycyclic aromatic hydrocarbons. This makes our filter sand the best sand available for monitoring well systems. Photo: [http://en.eijkelkamp.com/products/water/hydrological-research/groundwater-monitoring-pipes/filter-sand/filter-sand.htm Eijkelkamp Agrisearch Equipment BV.]]]
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:: *Moderate typically means 90-99% reductions of larger pathogens (helminth ova and larger protozoans) and solids-associated pathogens, but low(<90%) reductions of viruses and free bacteria, assuming no pre-treatment. With pre-treatment (typically coagulation), pathogen reductions are typically >99% (high).<br> **High pathogen reduction means >99%.
===Acknowledgements===
* [http://www.who.int/water_sanitation_health/dwq/wsh0207/en/index5.html Managing water in the home: accelerated health gains from improved water supply]. WHO.