The three predominate membranes used in residential and commercial water filtration processes are Reverse Osmosis (RO), Ultrafiltration (UF), and Microfiltration (MF). In certain specialized cases, Nanofiltration (NF) is used.
Each level of filtration removes certain sizes of molecules and reverse osmosis in addition can remove dissolved solids such as salts as well as dangerous particles such as radioactive particles occurring naturally in the drinking water or lead and other metals that seep into the water from ageing plumbing or industrial plants or pesticides.
Type of water filtration technology
The pore size on microfiltration membranes ranges from 0.1 – 5um, and has the largest pore size of the four main membrane types. Its pores are large enough to filter out such things as bacteria, blood cells, flour, talc and many other kinds of fine dust in solution. Because its pores are relatively large compared to other membranes, it can be operated under low pressures and therefore low energy.
Ultrafiltration has a pore size range of 0.1um to 0.01um. UF membranes reject particles such as silica, viruses, endotoxins, proteins, plastics and smog/fumes such as ZnO. Due to the decrease in pore size, the osmotic pressure required is higher than that of MF. Does not remove radioactive isotopes, viruses or salts and sugars
Nanofiltration has a pore size range of 0.001-0.01um. NF membranes can filter particles up to and including some salts, synthetic dies and sugars, however, it is unable to remove most aqueous salts and metallic ions, as such, NF is generally confined to specialist uses. Does not remove dissolved metal.
Reverse Osmosis (RO)
Reverse Osmosis has a pore size range of 0.0001um. It is by far the finest separation material available to industry. It is used on a large scale for the desalination and purification of water as it filters out everything but water molecules, with pore sizes approaching the radius of some atoms in many cases. This pore size means it is the only membrane that can reliably filter out salt, dissolved metal and metallic ions from water. A reverse osmosis water purifier protects you from the harmful effects of lead, heavy metals, chlorine, chemical contaminants, pesticides, pathogens, bacteria, viruses, and even radioactive materials.
What is Reverse Osmosis?
Reverse Osmosis (RO) uses a semi-permeable membrane filter (Thin Film Composite or TFC), very pure water is produced but still retains small traces of minerals. RO systems utilize a series of filters (sediment, granulated activated or block carbon), the TFC membrane.
This superior purifying process provides the highest quality of water. RO uses a semi-permeable membrane that has pores large enough to allow water molecules to pass through but small enough to block other types of molecules such as dissolved salts (ions) and other impurities like bacteria at 99.99%. This is the technology used to make (only the purest, but not all) bottled water, it is also the only technology capable of desalinating seawater.
How does Reverse Osmosis work?
When pressure is applied to water on one side of the membrane, water molecules are forced through to the other side of the membrane, producing purified water. Contaminants are essentially filtered out by the process. RO removes 0.0001-micron-size contaminants (the finest filter to date).
The most amazing aspect of RO is all of the impurities are separated and automatically removed through the drain so they don’t build up in the system like any other filtering system (like MF, UF and NF) and re-contaminate the water, thus keeping the membrane and water clean.
You are left with safe, clean-tasting and delicious drinking water that doesn’t have a bad taste or smell. This is the reason why RO membranes can last so long and perform like new ones with minimum maintenance even after years of operation.
What contaminants are removed from Reverse Osmosis?
A high-performing RO system can remove up to 99% of dissolved contaminants found in feed water. These common water contaminants include:
Certified Contaminants Reduction :
|Chromium (Hexavalent)||99.1%||Radium 226/228||80.0%|
Full List Of Contaminants Reduction :
|Silver||Yes||Arsenic + 3||Yes|
|Mercury||Yes||Arsenic + 5||Yes|
|Organic Contaminants Organic molecules with a molecular weight of < 300||Yes||Organic molecules with a molecular weight < 3005||Yes|
Will Reverse Osmosis remove minerals in water?
Yes, an RO system will strip out the minerals, it will also remove a plethora of chemical and bacterial contaminants. Tap water may contain a very small amount of minerals, but the quantity is much too small to have an impact on health.
For example, one glass of orange juice has more minerals than a bathtub of water.
The World Health Organization (WHO) made a clarification that the majority of healthy minerals needed for the human body are from food or dietary supplementary sources and not from drinking water. In addition, minerals found in water can be harmful to human health.
The evidence is strong that calcium and magnesium are essential elements for the human body (WQA, 2011). However, it’s a weak argument to suggest that we should make up for this deficiency through water consumption (WQA, 2011).
Tap water presents a variety of inorganic minerals that which human body has difficulty absorbing (Misner, 2004). Their presence is suspect in a wide array of degenerative diseases, such as hardening of the arteries, arthritis, kidney stones, gall stones, glaucoma, cataracts, hearing loss, emphysema, diabetes, and obesity.
What minerals are available, especially in “hard” tap water, are poorly absorbed, or rejected by cellular tissue sites, and, if not evacuated, their presence may cause arterial obstruction, and internal damage (Dennison, 193; Muehling, 1994; Banik, 1989).
The minerals in the water also include heavy metals which are sometimes toxic and radioactive. Water systems that don’t remove minerals will also leave these unhealthy metals & contaminants in your drinking water.
Reverse Osmosis removes inorganic minerals, metals and much more to provide you with the purest, healthiest and most natural drinking water.
Reverse Osmosis has little effect on water PH
Water pH levels will automatically change when it is ingested and comes into contact with the food in your stomach (Wise, 2011).
Even on an empty stomach, your stomach acid alone is already several times more acidic than RO water (pH 6.5-7.5) with a pH level of 2 (Wise, 2011). The human body regulates pH levels constantly to find balance and equilibrium (see Figure 2).
Therefore under normal conditions, it will always maintain a neutral 7.4 pH balance (Wise, 2011). A healthy body is very robust and it will restore homeostatic pH fairly quickly and easily (Wise 2011).
Soft drinks and sports drinks typically have a pH level of 2.5, orange juice has a 3 pH and coffee has a 4 pH level and we drink these beverages all the time without problems (Wise, 2011).
Benefits of Reverse Osmosis water
RO water is safer, the most cost-effective, filters on demand, is healthier, has no smell and tastes refreshing. Based on our research, no other process is as effective.
Water filtered or treated by RO is pure, clean, and healthy. RO treatment system is currently the only technology that can remove most of the emerging contaminants (i.e., prescription drugs and perchlorate) including other contaminants (i.e., Arsenic, Cyanide, and Fluoride) that are difficult to remove by other treatment methods.
No more ingesting of harmful inorganic minerals means the body will no longer be stressed with trying to absorb something that wasn’t supposed to be there in the first place (Wise, 2011).
Consumers should not be concerned about the removal of minerals by the RO system. WHO (2009) and WQA (2011) pointed out, that the human body obtains the vast majority of minerals from food or supplements, not from drinking water.
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