Reverse osmosis is a filtration process that is often used for water. It works by using pressure to force a solution through a membrane, retaining the solute on one side and allowing the pure solvent to pass to the other side. This is the reverse of the normal osmosis process, which is the natural movement of solvent from an area of low solute concentration, through a membrane, to an area of high solute concentration when no external pressure is applied.
Formally, reverse osmosis is the process of forcing a solvent from a region of high solute concentration through a semipermeable membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure.The membranes used for reverse osmosis have a dense barrier layer in the polymer matrix where most separation occurs. In most cases the membrane is designed to allow only water to pass through this dense layer while preventing the passage of solutes (such as salt ions). This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 2-17 bar (30-250 psi) for fresh and brackish water, and 40-70 bar (600-1000 psi) for seawater, which has around 24 bar (350 psi) natural osmotic pressure which must be overcome.
This process is best known for its use in desalination (removing the salt from sea water to get fresh water), but it has also been used to purify fresh water for medical, industrial and domestic applications since the early 1970s.
Osmosis describes how solvent moves between two solutions separated by a semipermeable membrane to reduce concentration differences between the solutions. When two solutions with different concentrations of a solute are mixed, the total amount of solutes in the two solutions will be equally distributed in the total amount of solvent from the two solutions. Instead of mixing the two solutions together, they can be put in two compartments where they are separated from each other by a semipermeable membrane. The semipermeable membrane does not allow the solutes to move from one compartment to the other, but allows the solvent to move. Since equilibrium cannot be achieved by the movement of solutes from the compartment with high solute concentration to the one with low solute concentration, it is instead achieved by the movement of the solvent from areas of low solute concentration to areas of high solute concentration. When the solvent moves away from low concentration areas, it causes these areas to become more concentrated. On the other side, when the solvent moves into areas of high concentration, solute concentration will decrease. This process is termed osmosis. The tendency for solvent to flow through the membrane can be expressed as "osmotic pressure", since it is analogous to flow caused by a pressure differential.
In reverse osmosis, in a similar setup as that in osmosis, pressure is applied to the compartment with high concentration. In this case, there are two forces influencing the movement of water: the pressure caused by the difference in solute concentration between the two compartments (the osmotic pressure) and the externally applied pressure.
Reverse Osmosis is the reverse, of the natural separation process of Osmosis, when the water in a saline solution of a lower concentration passes through a semi-permeable membrane over to a higher concentration saline solution and diluting it. The process occurs because in nature the solution of different saline concentrations, will attempt to become equal. The salt ions in the solution don't pass through the membrane but the water does. The Osmosis process in nature is an important mechanism in the operation of plant and animal cells. That's way the tree always gets fresh water even in saline environment. RO membranes have been used commercially since the 70's and they have improved to become very efficient. Today there are thousands domestic RO systems, in thousands of home around the world to produce purified drinking water and multimillion dollar desalination plants in many major cities.
Our Reverse osmosis filter systems are capable of removing the contaminants up to the values listed in the table below.
Aluminium up to 98% Ammonium up to 97% Arsenic up to 97% Barium up to 96% Bicarbonate up to 99% Bromide up to 99% Cadmium up to 98% Calcium up to 97% Chloride up to 99% Chromium up to 96% Copper up to 97% Cyanide up to 97% Fluoride up to 98% Iron up to 99% Lead up to 97% Sodium up to 99% Magnesium up to 99% Mercury up to 96% Nickel up to 97% Nitrate up to 95% Potassium up to 99% Selenium up to 95% Silica up to 95% Silver up to 95% Sulphate up to 99% Zinc up to 97%
Ultrafiltration is a type of filtration. Industries such as chemical and pharmaceutical manufacturing, food and beverage processing, and waste water treatment, employ ultrafiltration in order to recycle flow or add value to later products. Ultrafiltration is commonly abbreviated to "UF."
UF's main attraction is its ability to purify, separate, and concentrate target macromolecules in continuous systems. UF does this by pressurizing the solution flow. The solvent and other dissolved components that pass through the membrane are known as permeate. The components that do not pass through are known as retentate. Depending on the Molecular Weight Cut Off (MWCO) of the membrane used, macromolecules may be purified, separated, or concentrated in either fraction.
Currently, the study of UF processing occurs mainly in laboratory setups[citation needed] because it is very prone to membrane fouling caused by increased solute concentration at the membrane surface (either by macromolecular adsorption to internal pore structure of membrane, or aggregation of protein deposit on surface of membrane), which leads to concentration polarization (CP)). CP is the major culprit in decreasing permeate flux. Ultrafiltration is used as a pre-treatment step in reverse osmosis processes in many Middle Eastern countries to potable drinking water, as there is little fresh water available in those areas.
1. Empty plastics from bottled water end up in landfills endangering the environment.
2. Reusable water bottles are just as convenient to carry as bottled water. You can carry your filtered water with a reusable environmentally friendly glass, plastic, or stainless steel bottles. Refillable bottles with internal filter attachments are ideal for camping, hiking, travelling, or sporting events. You don't have to carry loads of bottled water to a camping or hiking trip.
3. Your filtered water is available for you in your own house at any time of the day. You can never run out clean healthy water unlike bottled water. Your water filtration system will provide uninterrupted healthy water for you and your family as long as you replace filter cartridge according to the manufacturers' recommendation.
4. Bottled water is more expensive than filtered water. Bottled water is an ongoing cost.
5. Harmful chemicals in plastic bottles can leach into water making it unhealthier than tap or filtered water.
6. If you are worried about the quality of the public water supply, a home test kit is available to find out if your water is contaminated. If test shows contamination, a certified water filtration system can give you clean, healthy water instead.
7. Government rules are more stringent on public water supplies than bottled water companies. Water authorities have to comply with several rules under the Safe water Act that do not cover bottled water.
8. It's more environmentally-friendly to switch from bottled water to tap or filtered water. Plastic bottle requires fuel for production and transportation which can increase pollution. Less demand for bottled water will reduce the chances of polluting the environment. Shipping bottles of water across the country and across the continent takes tremendous amount of fuel adding to air pollution.
9. Bottled water is not cleaner or healthier than tap or filtered water. NRDC testing of more than 1,000 bottles of different brands revealed a large percentage of contaminated bottled water. Their test also revealed that most bottled water is packaged municipal water that was simply chlorinated. Your own personal home filter system can do it much better.
In this day of massive environmental pollution, most people have some level of awareness about the need to purify their drinking water. Strangely though, many folks won't hesitate to shower in the same tap water they refuse to drink. Most are surprised to learn that waterborne chemicals, including fluorides, are readily absorbed into the body from showering or bathing. 1 In fact, these chemicals are actually more dangerous when absorbed through the skin, for in this manner they enter the bloodstream more easily, bypassing the gut where they would bind with minerals from food, thus diminishing their harmful effects. 2 A growing awareness about water pollution is prompting an increasing number of Americans to buy bottled water (which may be as contaminated as tap water) or invest in water filtration units. Many use activated charcoal, sediment filters, water softeners and/or ceramic filters. These will remove one or more of the following: organic chemicals, particulate matter, calcium ions and some microorganisms.None of these methods will remove fluoride. Many people see the presence of fluoride in their drinking water as beneficial, however, and therefore are not concerned with removing it. They should be.
Fluoride as an Industrial Pollutant
Due to highly successful PR campaigns by industry (and government on behalf of industry) over the past half century, many people mistakenly view fluoride as an essential nutrient. It is not. Fluoride, as it occurs naturally in water (as calcium fluoride), can cause many problems at high levels and is even more toxic when it is added to water supplies in the form of fluorosilicic acid, a waste product of the phosphate fertilizer industry that is part of a pollution concentrate that is heavily contaminated with toxins and heavy metals, such as arsenic, lead and cadmium (all carcinogens) and radioactive materials. 3 This form of fluoride is by far the most widely used today to fluoridate public water supplies.
What to Do?
If you learn that your water supply is fluoridated, you'll want to make efforts to have the fluoridation decision reversed. At the same time, you'll want to assure that your own drinking (and bathing) water is fluoride-free. Water distillers and reverse osmosis systems effectively remove fluoride, along with other dangerous chemicals and are a practical and cost-effective solution to treating drinking water. Unfortunately, however, these methods are neither practical nor cost effective for treating all of the water coming into your home. Whole house filtration is necessary if your water supply is fluoridated because there is no shower filter on the market capable of removing fluoride - and fluoride, as previously mentioned, is readily absorbed through the skin (sidebar). There are three types of filtration media that will remove fluoride from water: bone char (a form of carbon), alumina (aluminium oxide) and a fluoride ion exchange resin. Knowledgeable water treatment professionals in your community can provide details about these filtration options. It should be noted that fluoride is not removed from water by boiling; it only becomes more concentrated in this manner. Even if you have effectively removed fluoride from your drinking and bathing water, if you are living in a fluoridated community, you will still need to exercise caution when dining out, for the water served - and everything made with it, like coffee - will contain fluoride. Aside from drinking only non-fluoridated water, you'll want to buy only unprocessed foods. Choose whole foods that are grown organically, without use of chemical fertilizers or pesticides. The ultimate solution to the fluoride pollution problem, however, is to stop fluoridation.
Carbon has been used for long time to absorb impurities and is perhaps the most powerful absorbent known to man. One pound of carbon contains a surface area of roughly 125 acres and can absorb literally thousands of different chemicals. Activated carbon has a slight electro-positive charge added to it, making it even more attractive to chemicals and impurities. As the water passes over the positively charged carbon surface, the negative ions of the contaminants are drawn to the surface of the carbon granules.
There are two different types of carbon used in water filtration, Carbon Block and (GAC) Granular Activated Carbon. Although both are effective, carbon block filters generally have a higher contaminant removal ratio. The two most important factors affecting the efficiency of activated carbon filtration are the amount of carbon in the unit and the amount of time the contaminant spends in contact with it. More carbon the better it is, particle size also affects removal rates.
Activated carbon filters are usually rated by the size of the particles they are able to remove, measured in microns, and generally range from 0.5 microns (most effective) to 50 microns (least effective).
Our filters use coconut shell carbon, which costs about 15-20% more but is the most effective.
Applications
Carbon filters are very common in a number of home water treatment systems. It can be used as a standalone filter to reduce or eliminate bad tastes and odours, chlorine, and many organic contaminants in municipal (pre-treated or chlorinated) water supplies to produce a significantly improved drinking water. It is also very commonly used as a pre-treatment as part of a reverse osmosis system to reduce many organic contaminants, chlorine, and other items that could damage the reverse osmosis membrane.
Carbon filters require very little maintenance, however, it is very important to ensure that filter replacement schedules are followed to ensure proper filtration at all times. Filters should be changed before the bad taste and odours return.
What does carbon remove?
Carbon filters remove, reduce many (VOC) volatile organic chemicals, pesticides and herbicides, as well as chlorine, benzene, solvents and hundreds of other man-made chemicals found in tap water. Some activated carbon filters are moderately effective at removing some, but not all, heavy metals. In addition, densely compacted carbon block filters mechanically remove particles down to 0.5 micron, including Giardia.
Carbon filters are NOT generally successful at removing dissolved inorganic contaminants or metals such as minerals-salts (hardness or scale-causing contaminants), antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, copper, fluoride, mercury, nickel, nitrates-nitrites, selenium, sulphate and thallium. Removing these contaminants requires either a reverse osmosis water filter system or a distiller (some can also be removed by KDF-55 or manganese greensand).
Granular Activated Carbon (GAC) does not remove sediment - particulate material very well, so they are often preceded by a sediment filter. Sediment pre-filters also prolong the activate carbon cartridge life by eliminating gross contaminants that would otherwise clog the activated carbon thereby reducing the surface area available for absorption. Carbon block filters are generally better then GAC filters at removing sediment.
