Difference between revisions of "Granular filtration"
From Akvopedia
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|- | |- | ||
|Granular media, rapid rate depth filter | |Granular media, rapid rate depth filter | ||
| − | |Sand, gravel, diatomaceous earth, coal, other minerals | + | |'''Sand, gravel, diatomaceous earth, coal, other minerals''' |
|High | |High | ||
|Easy to Moderate | |Easy to Moderate | ||
| Line 26: | Line 26: | ||
|- | |- | ||
|Slow sand filter | |Slow sand filter | ||
| − | |Sand | + | |'''Sand''' |
|High | |High | ||
|Easy to moderate (community use) | |Easy to moderate (community use) | ||
| Line 33: | Line 33: | ||
|- | |- | ||
|Vegetable and animal derived depth filters | |Vegetable and animal derived depth filters | ||
| − | |Coal, sponge, charcoal, cotton, etc. | + | |'''Coal, sponge, charcoal, cotton, etc.''' |
|Medium to high | |Medium to high | ||
|Moderate to Difficult | |Moderate to Difficult | ||
| Line 40: | Line 40: | ||
|- | |- | ||
|Fabric, paper, membrane, canvas, etc. filter | |Fabric, paper, membrane, canvas, etc. filter | ||
| − | |Cloth, other woven fabric, synthetic polymers, wick siphons | + | |'''Cloth, other woven fabric, synthetic polymers, wick siphons ''' |
|Varies: some low; others high | |Varies: some low; others high | ||
|Easy to moderate | |Easy to moderate | ||
| Line 47: | Line 47: | ||
|- | |- | ||
|Ceramic and other porous cast filters | |Ceramic and other porous cast filters | ||
| − | |Clay, other minerals | + | |'''Clay, other minerals''' |
|Varies: high- low, with materials availability and fabrication skill | |Varies: high- low, with materials availability and fabrication skill | ||
|Moderate. Must be physically cleaned on a regular basis to prevent clogging and biofilm growth | |Moderate. Must be physically cleaned on a regular basis to prevent clogging and biofilm growth | ||
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|- | |- | ||
|Septum and body feed filters | |Septum and body feed filters | ||
| − | |Diatomaceous earth, other fine media | + | |'''Diatomaceous earth, other fine media''' |
|Varies | |Varies | ||
|Moderate to difficult; dry media a respiratory hazard | |Moderate to difficult; dry media a respiratory hazard | ||
Revision as of 19:21, 6 October 2012
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
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: Eijkelkamp Agrisearch Equipment BV.
| Type Of Filtration | Media | Availability | Ease of Use | Effectiveness | Cost |
|---|---|---|---|---|---|
| Granular media, rapid rate depth filter | Sand, gravel, diatomaceous earth, coal, other minerals | High | Easy to Moderate | Moderate* (depends on microbe size and pre-treatment) | Low to moderate |
| Slow sand filter | Sand | High | Easy to moderate (community use) | High** in principle but often low in practice | Low to moderate |
| Vegetable and animal derived depth filters | Coal, sponge, charcoal, cotton, etc. | Medium to high | Moderate to Difficult | Moderate* | Low to moderate |
| Fabric, paper, membrane, canvas, etc. filter | Cloth, other woven fabric, synthetic polymers, wick siphons | Varies: some low; others high | Easy to moderate | Varies from high to low (with pore size and composition) | Varies: low for natural; high for synthetics |
| Ceramic and other porous cast filters | Clay, other minerals | Varies: high- low, with materials availability and fabrication skill | Moderate. Must be physically cleaned on a regular basis to prevent clogging and biofilm growth | Varies from high to low (with pore size and ceramic filter quality) | Moderate to high |
| Septum and body feed filters | Diatomaceous earth, other fine media | Varies | Moderate to difficult; dry media a respiratory hazard | Moderate | Varies |
- *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).
**High pathogen reduction means >99%.
