Household Water Filter or Purifier Methods

(Last Updated On: September 14, 2016)

The water purifier way consists of microfiltration (MF), ultrafiltration (UF) and reverse osmosis (RO) membrane, filtration precision from low to high. MF belongs to the ordinary general microfiltration filtering can filter suspended solids, large odor etc.. The filtration effect of ultra filtration is in the middle, and the filtration precision of the reverse osmosis membrane is the highest, which can be used for seawater desalination. In addition, particle filter (particle adsorption) and ion exchange, can filter bacteria and heavy metal ions.

5 stage filtration

5 stage filtration

1 Microfiltration

Material: PP cotton, or the filter metal mesh.
Can be filtered: smoke, latex, asbestos, pigments, bacteria, etc.

2 Ultra filtration: filter out impurities of 0.01 micron or more

Materials: PES, PVDF, etc.
Can be filtered: gel, albumin, carbon black, endotoxin, virus, etc.

3 Reverse osmosis: can filter out impurities below 0.001 microns

Material: aromatic polyamide

4 Particle filter: filter 1 microns or more impurities

Material: activated carbon, filter net, etc.
Filter: fine dust, ash, pollen, flagellate cells, red blood cells, bacteria, etc.

5 ion exchange: filtration of heavy metal ions, also known as KDF filter

Material: is a kind of high purity copper zinc alloy, is a kind of new filter media, the use of oxygen reduction reaction, electronic exchange and release of pollutants, or electronic, many of the pollutants into harmless substances
Filter: remove heavy metals such as lead, cadmium, mercury and other heavy metals. Ion exchange also called soft purifier.

Filter material distribution, corresponding to the size of the harmful substances, as follows:
Sediment, rust: 50 micron
Bacteria: 0.5 micron
Viruses: 0.02 micron
Heavy metal ion:  0.005 micron.

For each filtration, manufacturers will take some good promotion, such as ceramic membrane filtration, nano technology, PVC alloy, ACF ultrafiltration membrane filtration, in fact can be attributed to several filtering methods above, only the difference between pore size.


Doulton filter design

A collection of several filtration in a stratified composite filtration method, such as the famous five layer filtration from the loose to tight filter, which is a collection of five kinds of filtering methods, including pre PP cotton, activated carbon, fine PP cotton, RO membrane or ultrafiltration membrane, activated carbon filter, most filter is the variant or simplified version of the five kinds filter .

General filter can use the independent function of the filter material, also can be a composite filter. The benefits of independent function of the general size of the larger filter, filter water capacity is also large, can only replace the separate function filter, the general under sink or the central filter system are using the separate filter. The utility model has the advantages of small size and convenient installation, but the disadvantage is that the replacement has to be totally replaced with the filter material, maybe high cost, and is suitable for the counter top filter, faucet tap filter, the pitcher or the small space kitchen under sink filter.


Aquasana under sink filter

The different filter material, the different combination, the different amount of filter water, the formation of hundreds of different filters, but the key points are:
1, filter aperture, which size substances can be removed;
2, whether there is ion exchange, to determine whether the removal of heavy metal ions;
3, the material is environmentally friendly, such as coconut shell activated carbon, etc.;
4, filter capacity, directly related to how long the need to replace the filter material;
5, whether with self cleaning function, in order to extend the service life of the filter element;
6, whether the filter is internally keep water, to avoid the second bacteria breeding;
7, what certification.

Now advanced filters generally have automatic filter element replacement reminder function, otherwise it is necessary to determine the following information:
1, the sense of water
2, the flow of water is small: the filter cartridge is blocked, should be replaced in a timely manner. Replace the pre filter cartridge first, if the flow is still very small which can not meet the demand, it is necessary to replace the fine filter element.
3, on their own calculations: we generally use the time to achieve their ideal life of about 80% of the time to replace.


Doulton filter certification

The authority of the filter certification generally have the following four ways:
1, the United States FDA certification, the United States Food and Drug Administration
2, the United States WQA certification, Quality Association Water
3, the NSF certification of WHO, in terms of food safety and drinking water safety and treatment of designated units
4, where the country’s health permits, such as MOH in China, WRAS in UK.

Understand the filtering methods and principles, the selection of the filter can be judged according to your own needs, do not be misled by the new term business promotion words of the Brands.

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