Most Effective Methods Of Water Purification

by Optimum Nutrition Admin
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A review of water distillation systems

There are many types of water purification systems available that vary widely not only in the contaminants they remove but where they are removed (e.g. sinks, showers, whole house) and at what cost. It is important to distinguish between the primary objectives of water treatment systems, namely purification and disinfection. Water purification is the removal or elimination of any contaminant and all treatment systems will provide some form of purification. Water disinfection is the destruction or removal of microorganisms such viruses, bacteria, protozoa and other infectious agents. Only certain types of treatment systems eliminate biological organisms which are ozone generators, ultra violet light treatment and distillation. While these methods kill pathogens, the types and amounts of other contaminants they remove from the water differs greatly. No single method will provide complete purification and, typically, the higher the quality and effectiveness of the system, the higher the price tag and frequency of maintenance.

The following represent the most popular types of water purification systems with each category possessing significant equipment variations:

  • Sediment filters
  • Activated carbon filters
  • UV light treatment systems
  • Distillation systems
  • Reverse osmosis systems
  • Ozone generators

Each of the above systems is available in point of use or point of entry types. Point of use (POU) water treatment equipment is designed to treat small amounts of drinking water for use in the home. These devices can be countertop units, faucet or shower head attachments, or under sink installations. They differ from point of entry (POE) devices which are installed on the incoming water line to decontaminant all the water flowing into the home. The most common point of use (POU) location is the kitchen sink. Only the water that is actually used for drinking, cooking and beverage and food preparation is treated. Purifying the water at this single location is economical since only a few hundred gallons of water need to be treated per year instead of thousands of gallons that would be treated by a whole-house (POE) system. POU and POE systems have their advantages and disadvantages and should be evaluated based on the desired level of purification, the initial and ongoing costs and their ability to eliminate the water problems specific to one’s household.

One of the most cited objections to investing in any type of water purification equipment (besides the cost) is that essential minerals are removed from the water – particularly from distilled water. This is an extremely ignorant reason to reject something that would provide safer, cleaner drinking water for an entire family. Yes, beneficial minerals can and should be removed by an effective system. If the equipment did not extract these minerals, it would not be able to filter out any inorganic contaminants such as arsenic, asbestos, barium, lead or mercury to name a few. Again, a good treatment system has the potential to kill or remove bacteria, viruses, cysts, heavy metals, radionuclides, particulates, organic compounds and inorganic compounds, which include beneficial minerals. Equally untrue is the myth that water devoid of beneficial minerals due to purification will leach the minerals that exist within the human body when the purified water is consumed. Muscle testing will verify this misconception is false.

The reality is that the amount of beneficial minerals being derived from one’s water is negligible at best, regardless of the source. For example, a person living in Boston, Massachusetts and drinking the municipal tap water would have to consume 42 gallons of water every day in order to obtain the recommended daily allowance (RDA) of calcium. It would require over 115 gallons a day to receive enough magnesium, 53 gallons per day for iron and a whopping 10,560 gallons every day to acquire a sufficient amount of phosphorus. If anyone believes they are receiving the necessary minerals to live from their water does not understand nutrition whatsoever. Even if someone is fortunate enough to have an abundant amount of beneficial minerals coming from a deep, underground spring or well, eliminating the risk of contamination and their potentially deadly effects on the body more than justifies the loss of minerals in the process. Does it make sense to consume harmful toxins and pathogens just to save the minerals present which, in the vast majority of cases, is a miniscule amount? Minerals can and should be obtain from other sources, specifically food and supplementation.  If minerals being present in your drinking water are a priority, purchase a pure above-sea coral calcium powder and add it to your filtered water.  Coral minerals are ionic; therefore, 92% of the 73 beneficial minerals present are immediately absorbable.  This will give your water more minerals than it ever could have had, even in a pristine, natural state.

Sediment Filters

Sediment filters act as a sieve to remove solid particles from a water supply. It is important to realize that these filters do not remove microorganisms or dissolved compounds such as chemicals or heavy metals. Pressure forces the water to be filtered through a porous material, trapping the sediments. These filters come in a variety of sizes from fine to coarse, with the lower micron rating being the finer. The finer the filter, the more particles the filter will remove and the more frequently it will need to be replaced. Sediment filters are further classified as nominal or absolute. For example, a nominal five micron filter can remove 85% of particles from the water that are three microns and larger. An absolute three micron filter can screen out 99.9 % of particles three microns and larger. If sediment filtration is to be the treatment system of choice, it is best to use an absolute-rated filter.

Sediment filters basically consist of two types of material – fiber and ceramic. Fiber filters use materials such as cellulose, polypropylene, polyester, cotton or rayon that are woven into a tight but porous mess. Fiber filters are often used as prefilters to remove larger particles that could clog an activated carbon or reverse osmosis filter. Fiber filters will not remove organic or inorganic compounds (chlorine, lead, mercury, trihalomethanes, etc.) that are dissolved in the water or any microorganisms. Ceramic filters’ function is similar to fiber filters except water is forced through a porous ceramic material. If the pores of the ceramic are small enough, this filter can reduce asbestos fibers and other particulate matter. Also like fiber filters, ceramic filters will not remove dissolved organic or inorganic compounds, viruses or any other pathogens. Ceramic filters may be used in conjunction with other purification systems to prevent clogging and achieve a more thorough cleansing of contaminants.

While sediment filters are relatively inexpensive, they do not change the way water tastes or smells and their effectiveness as a comprehensive purification system is marginal. They are a poor choice as a stand-alone solution to water decontamination unless it is the only option for a limited budget. However, as an additional component on other treatment systems, sediments filter increase overall system performance, reduce clogging and minimize equipment maintenance.

Activated Carbon Filters

Activated carbon is particles of carbon that have been treated to increase their surface size and absorption ability for the filtration of soluble substances, particularly organic compounds. Contaminate reduction is accomplished by forcing water through a column containing active carbon, a highly porous material, which absorbs a wide range of contaminants. The effectiveness of an active carbon (AC) filter depends on the temperature and the nature of the substances. The filtration process is influenced by the following factors: 1) the carbon’s pore size and surface area, 2) the type of carbon medium, 3) the chemical composition and concentration of contaminants, 4) the water pressure and 5) the extent to which the contaminants are exposure to the carbon medium. The amount of activated carbon within the filter and the contact time the water has with it will the greatest impact on contaminant removal. The more contact time and the denser the carbon medium, the better the results.

Contaminant reduction is accomplished two ways: 1) trapping solid particles that are too large to pass through the pores and 2) the adsorption of dissolved contaminants that are attracted to the surface of the carbon medium. The characteristics of the carbon material (such as particle and pore size, surface area, surface chemistry, density and hardness) all effect the degree to which impurities are eliminated. Microorganisms are not killed or filtered by activated carbon and, in actuality, they can promote bacteria growth if not properly maintained or periodically replaced. Over time, AC filters will eventually be less effective at reducing contaminants as the pores become clogged and its adsorptive surfaces become saturated with dissolve substances. Finally, since it is difficult to know when these filters have become saturated with contaminants and because they are subject to bacterial buildup, flushing and cartridge replacement should be conducted in accordance with the manufacturer’s specifications. Also noteworthy, particularly when using countertop and faucet mounted carbon filtration systems, hot water should never be run through a carbon filter as it will damage it.

There are essentially two types of carbon filters – granular and solid block. In granular activated carbon filters, water flows through a bed of loose activated carbon granules which trap some particulate matter while removing some chlorine and other inorganic compounds, some organic contaminants and most undesirable tastes and odors. Loose granules of carbon do not restrict the water flow to the same extent as solid block AC filters. This enables them to be used in situations like whole house filters where low flow rate and water pressure may be an issue. Granules AC filters require simple, economical maintenance with a typical filter cartridge needing to be changed every few months to a year, depending on water use, level of contamination and the manufacturer’s specifications. Granular AC filters do not require electricity or waste water.

Granular filters are effective and valuable treatment devices however, like all purification systems, their limitations need to be evaluated. Granular AC filters, like all activated carbon filters, do not naturally reduce the levels of soluble salts, nitrates, fluoride or potentially harmful minerals like arsenic and cadmium. Also, on their own, they cannot reduce microorganism contamination. Their primary design shortcomings are channeling, dumping and large pore size. Water seeks the path of least resistance so water flowing through the filter can potentially “channel” around the carbon granules and avoid filtration. Channeling is difficult to detect therefore one will assume all water is being filtered when, in actuality, it is not. Dumping occurs when pockets of contaminated water that have formed in the filter collapse with the change in flow rate or water pressure. This “dumps” the contaminated water into the already filtered flow. Granular AC filters large pore size allows many small substances, not subject to absorption, to pass through the filter.

Solid block AC filters contain carbon that has been specially treated, compressed and bonded to form a solid, uniform matrix. This solid block allows for a much smaller pore size than a granular AC filter. This allows for the removal of smaller particles and provides longer contact time with the activated carbon for more complete contaminant reduction. If the pore size is small enough (0.5 micron or smaller), bacteria that become trapped do not have the space to multiply, eliminating the bacterial accumulation problem commonly seen in granular AC filters. The solid block AC filters’ design provides greater adsorption of many different chemicals (pesticides, herbicides, chlorine, chlorine byproducts, etc.) and more thorough filtration of parasitic cysts, asbestos and other particulates. When combined with certain specialized materials, these filters can be modified to remove other contaminants such as lead, mercury and arsenic. The rigid structure of the solid block AC filter also eliminates the channeling and dumping issues associated with granular filters. Solid block AC filters do not require electricity to be completely effective and do not waste water like reverse osmosis. They require simple, economical maintenance with a typical filter cartridge needing to be changed every few months to a year, depending on water use, level of contamination and the manufacturer’s specifications.

There are fewer weaknesses to solid block filtration than granular, but some do exist. Like granular filters, solid block filters are less effective at removing nitrates, chloride and heavy metals such as cadmium, chromium, copper, lead and mercury. Due to the dense material and smaller pore size, water flow can be restricted; therefore, households with inherently lower water pressure may not be able to use this type of filter. With usage and contaminant accumulation, the problem of restricted water flow is exacerbated. Also, like most other systems, as solid block AC filters remove impurities from the water, they gradually lose effectiveness until they are no longer able to adsorb or filter contaminants. Detecting when a filter is nearing the end of its effective life cycle is exceptionally difficult. Adhering to the manufacturer’s guidelines for cartridges replacement is always recommended.

UV Light Treatment Systems

Ultraviolet light is one of Nature’s powerful disinfectants. A UV treatment device possessing sufficient intensity and the correct wavelength can destroy microorganisms such as bacteria, viruses and protozoa. Disinfection occurs when water flows through a clear chamber where it is exposed to an ultraviolet bulb. If the light is of sufficient intensity for the type of water to be treated, it will destroy the genetic material of the pathogens. The effectiveness of a UV system is contingent upon the clarity of the incoming water supply. If the light is block by particulates or dissolved organic/inorganic matter, the infectious agents could be completely or partially shielded from exposure and therefore survive the disinfection process. Consequently, water may need to be filtered to remove solid particles prior to UV treatment. The primary strengths of a ultraviolet system are that it destroys, or renders inactive, pathogenic microorganisms in a matter of seconds without introducing any toxic or significant nontoxic byproducts into the water. A UV system adds no smell or taste to the treated water and in certain situations will remove some existing odors and foul taste.

There are significant weaknesses inherent to UV devices. As previously stated, UV treatment is not suitable for water with high turbidity (substances that scatter light). These substances can react with ultraviolet radiation and reduce performance. Turbidity makes it difficult for radiation to penetrate water and pathogens can be shadowed, protecting them from the light. UV light has no effective on non-living contaminants such as lead, asbestos, organic chemicals, chlorine, flouride and so on. Resilient cryptosporidia cysts are fairly resistant to ultraviolet light. UV light can also alter some organic compounds into equally harmful byproducts. UV devices are insufficient for comprehensive purification unless combined with a reverse osmosis system or activated carbon filter.

Ozone Generators

Like ultraviolet light, ozone (O3) is another of nature’s natural disinfectants but it also eliminates some other contaminants. Ozone is a naturally occurring component of fresh air consisting of three oxygen atoms. The oxygen (O2) we breathe possesses only two chemically linked oxygen atoms. Lighting storms leave a very distinct fresh smell in the air which is large amounts of ozone created by the electrical discharges of the lighting bolts. Ozone is also created by the Sun’s ultra violet rays which forms the layer of ozone in the Earth’s upper atmosphere. Ozone is very reactive and unstable with a short existence before it reverts back to oxygen or attaching to another atom. In other words, one of the three oxygen atoms has a weak connection on the others and easily transfers its electrons to substances in air or water (oxidation). Manmade ozone is accomplished either by an electrical field, as in the corona discharge type ozone generators, which simulate lightning, or by ultraviolet light used by UV type ozone generators, which simulate sunlight. The ozone is then injected or diffused into the water supply. Note: ultraviolet ozone generators typically produce a lower output than corona discharge devices and tend to be more expensive.

There are many advantages to using an ozone generator that go beyond water treatment. First and foremost, ozone is an effective and efficient disinfectant that kills microorganisms. Being it is the most powerful and rapid acting oxidizer man is able to create, ozone will oxidize (eliminate) all bacteria, viruses, mold and yeast spores and some organic material given sufficient exposure. Ozone also oxidizes and precipitates iron, sulfur and manganese so they can be filtered out of the water. Ozone adds no taste or odor to the water and in many cases will improve both. Since ozone is a derivative of oxygen and reverts back to pure oxygen, it quickly dissipates after being released into water so there are no residual disinfectants. Ozonation can also affect turbidity which is the suspension of microscopic or colloidal particles, both organic and inorganic. These particles often possess a positive electrical charge as opposed to ozone which has a negative charge. When the two collide, the particles are oxidized and will precipitate. Ozone can be used to disinfect fruits and vegetables when submerged in ozone treated water. When water or olive oil that has just been treated with ozone is consumed, it will kill intestinal worms and some species of protozoa.

A major weakness of ozone treatment is that it is primarily a disinfectant and therefore is not effective as a stand-alone purification system. In fact, if some water is not prefiltered, harmful byproducts can be created such as formaldehyde and bromate. Also, ozone is not effective at removing dissolved salt or minerals. Because ozone is so reactive, the internal parts of inexpensive units that are exposed to the ozone, particularly the rubber diaphragm, can quickly degrade. However, when quality ozone generators are combined with other treatment systems, such as activated carbon filters or a reverse osmosis device, the level of purification is tremendous.

Reverse Osmosis Systems

Reverse osmosis device requires water pressure to force water molecules through several filters which remove particulates and dissolved substances. Osmosis is the natural tendency for water molecules to pass through a semipermeable membrane consisting of extremely small pores (0.0001 microns), from the side low in dissolved impurities to the side high in dissolved impurities. The component unique to a reverse osmosis system is the membrane which removes dissolved solids at the ionic level. The purified water is collected from the clean side of the membrane while water containing the impurities is expelled from the device. The typical reverse osmosis (RO) system is a unit consisting of a sediment prefilter, the semipermeable membrane, a collection tank and an activated carbon post filter.

RO systems significantly reduce most all contaminants including inorganic and organic compounds and microorganisms with the purity of the treated water approaching the level produced by distillation systems. Reverse osmosis is an excellent method for decontaminating water with high levels of dissolved inorganic contaminants that can not be removed effectively or economically by other devices. A good example of this is people with wells in areas where agribusiness introduces high levels of nitrates. RO devices are also often used to desalinate seawater or brackish water. Though slower than activated carbon or sediment filters, RO systems can typically purify more water per day than distillers. Most RO systems do not use electricity however they do require fairly high water pressure to operate effectively. There are portable countertop models that use electricity.

The most significant disadvantage to using a RO system is the large amount of contaminated wastewater generated. This can be as much as 50 to 90 percent of the incoming water. The amount depends mostly on the water pressure difference across the membrane. The greater the pressure difference, the smaller the wastage rate. Typically, two to four gallons of contaminated water are flushed down the drain for each gallon of purified water produced. If you live in an area with high municipal water rates, this system may not be an economically sound choice. Another potential downside is the possible existence of a defective to damaged membrane which are extremely difficult to detect. This situation could allow pathogens and other substances to escape filtration undetected into what one would be assuming is purified water. Additionally, many factors affect the reverse osmosis membrane’s efficiency which include contaminant concentration, chemical properties of the contaminants, the quality of the membrane and its condition, water pH, water temperature and water pressure. An electric pump can be used to increase water pressure if needed. Like all purification systems, RO devices require cleaning and maintenance. The prefilter, post filter and membrane must be changed according to the manufacturer’s specifications and the storage tank must be cleaned periodically.

Distillation Systems

The distillation process passes water over a heated coil‚ causing the water to vaporize and become gaseous. The steam rises, leaving most contaminants behind. It then transfers to a cooling chamber where it condenses back into a liquid. The resulting distillate drips into a storage container. Salts, sediment and inorganic compounds like lead‚ cadmium and radon (anything that does not boil or evaporate) remain in the distiller. The boiling water of distillation also destroys microorganisms which are also left behind in the tank. Distillation is less effective at removing organic chemicals (volatile organic chemicals or VOCs) since many of them possess a lower boiling point than water and therefore are vaporized into the steam. Most quality distillation systems include a VOC gas vent and carbon activated post filter giving these systems an impressive 99% contaminant removal rate. Distillation is one of the few practical ways to remove heavy metals, nitrates, chloride and salts that sediment filters, activated carbon filters and ozone generators have difficulty removing. Another attribute of a distiller is that the high quality of purification will be very consistent regardless of the water source. Unlike sediment, carbon and RO filters, there is no decrease in performance or water quality over time as long as the components are kept clean. Distillers require periodic cleaning of the boiler, condensation unit and storage tank.

There are several primary drawbacks to distillation. First, it takes a considerable amount of time to purify water which can be nearly five hours to produce a single gallon of clean water. Needless to say, this results in a significant usage of electricity making distillation one of the more expensive in terms of ongoing costs. Also, the method of purification cannot be for a point of entry (whole house) application therefore only the household’s drinking will be clean. Finally, many countertop units are low quality devices sold by multilevel marketing companies. These units typically do not include AC filters or VOC vapor traps. Like all purification systems, complete removal of contaminants requires a combination of methods therefore a vapor trap, carbon filter or other device must be used in conjunction with a distiller.

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