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Centralized Water Treatment
Building hi-tech water treatment plants to remove impurities aren`t the solution: Only 2% of water supplied to our homes is used for human consumption. A large percentage of our population has small rural or private well supplies for water. These would not be benefited by large municipal treatment centers. It isn`t logical to build costly plants to treat the water we use for our lawns, to flush our toilets, and to fight fires. It`s evident that it isn`t practical to upgrade our treatment plants to treat all the water they process. It has the opportunity to pick up materials from the pipes before coming out of the tap.
Boiling Water
Boiling reduces the threat of living organisms. It serves as a method for killing bacteria during emergencies, it is not recommended for long term use. Very little is removed by boiling. You may kill germs, but you still have dirt, sediment, dissolved solids, bad taste, and odor remaining - there may also be many chemical contaminants.
Bottled Water
Is the solution for safe drinking water provided y paying $.80 to $2.00 per gallon to drink water prepared and bottled by someone else? This cost ineffective price reflects the costs of bottling, storage, trucking, fuel expenses, wages, insurances, etc. If you have a point of use water system, you eliminate all of these middleman costs, and enjoy purified water for pennies per gallon.
Point of Use Water Treatment
The most efficient and cost effective approach to the problem of water purity is to treat JUST the water you will consume for drinking and cooking WHERE you will consume it. Devices for point of use water treatment are available in a wide variety of sizes, designs, and have varied claims as to their ability to remove impurities.
Mechanical Filtration
One of the most widely used water quality improvement methods is mechanical filtration which acts much like a fine strainer. Particles of suspended dirt, sand, rust, and scale (i.e. turbidity) are rapped and retained, greatly improving the clarity and appeal of water. When enough of this particulate matter has accumulated in or within the filter element, it is usually discarded. This type of filter is usually considered a pre-filter.
Ultraviolet Disinfection
Ultraviolet light, at the germicidal wavelength of 253.7 nanometers, alters the genetic (DNA) material in cells so that bacteria, viruses, molds, algae and other microorganisms can no longer reproduce. The microorganisms are considered dead, and the risk of disease from them is eliminated.
As the water flows past the UV lamps in UV disinfection systems, the microorganisms are exposed to a lethal dose of UV energy. UV dose is measured as the product of UV light intensity times the exposure time within the UV lamp array. Microbiologists have determined the effective does of UV energy (expressed in microwatt - seconds/cm2) needed to destroy pathogens as well as indicator organisms found in waste water.
Used properly, ultraviolet light effectively destroys bacteria, viruses and other microorganisms in water and waste water, without using chemicals. By doing away with chemical treatment, many other problems are also eliminated. There is no longer need to worry about operator safety of the requirement for buildings for storage and handling dangerous solutions and gases. Costly liability insurance premiums are significantly reduced. Testing of effluent for chlorine residual is no longer necessary, and toxicity problems associated with chlorine use are eliminated.
Ultra filtration/Reverse Osmosis
Osmosis occurs in living organisms in which there is a piece of tissue or a membrane with fluids on either side of it. Fluids having a lesser concentration will be drawn through the tissue/membrane to mix fluids having a greater concentration. This is to equalize the concentration of substances in the fluids on both sides of the tissue/membrane. This can be illustrated if you cut open an avocado, and salt the surface on one half. In a short time, you will notice water has been drawn out of the avocado to try to equalize the concentration of salt placed on the surface of the avocado. Reverse Osmosis occurs when there are two fluids of differing concentration separated by semi-permeable membrane. The fluid will pass through the membrane in the direction of the most concentrated solution. When we quench out thirst with water, a quantity us placed in our stomach. This water will be diffused into our system to replenish what is lost as the life processes.
In the natural world surrounding us, inside of use, there is a vast network of biological membranes. These screening barriers govern the selection and passage of chemicals and fluids. In essence, these membranes control the traffic of the life processes themselves.
Membranes help organisms carry out an immense variety of exchanges with their environment. The gills of a fish obtain oxygen from water. Our lungs extract oxygen from the air and place it in our blood stream. In plants, the cell walls allow photosynthesis to take place by providing the medium for the transfer by many seeming miraculous processes.
One integral function is that of the kidneys. As the blood enters the kidney, it flows in smack arteries in close contact with tiny excretory units of the kidney known as nephrons. From the blood, water is extracted along with wastes to become an essential component of urine. Water can remain in the nephron to become reabsorbed back into the blood stream if not enough water is consumed to be excreted freely. Without our kidneys, we would not be able to survive. The first artificial kidney was built from a cellophane membrane in 1994. In the early 1950`s, Drs. Sidney Loeb and S. Sourirajan from UCLA Medical School developed the first synthetic membrane made from cellulose acetates. This had commercial Reverse Osmosis Capabilities.
Reverse Osmosis is exactly the opposite of osmosis. In Reverse Osmosis (RO), water having a lesser concentration of substances is derived from water having a higher concentration of substances. Tap water with dissolved solids and other materials in it is forced by water pressure inherent in our water pipes against a membrane. The water is removed from this concentration of materials by penetrating the RO membrane, and leaving the materials behind - this can be up to a 99% removal of dissolved solids.
The RO membrane is an ultimate mechanical filter, or ultra filter. It strains out virtually all particulate material, turbidity, bacteria, microorganisms (on potable water only), and asbestos, even single molecules of the heavier organics. To appreciate the fineness of this membrane or ultra-filter, its pore size would be two one hundred millionths of an inch in diameter. That`s smaller than what can be seen by an optical microscope! By the remarkable phenomenon of RO, particles smaller than water molecules themselves are removed! The molecules diffuse through the membrane in a purified state, and collect on the opposite side. Ultra-filtration/RO membranes remove and reject such a wide spectrum of impurities from water using VERY MINIMAL ENERGY - just water pressure. RO gives the best water available for the lowest price expended.
Reverse Osmosis Effectively Reduces the Following:
- Particulate matter, turbidity, sediment, etc.
- Colloidal matter.
- Total Dissolved solids (up to 99%).
- Toxic metals.
- Radium 226/228
- Microorganisms (potable water only)
- Asbestos
- Pesticides and herbicides (coupled with AC)
Reverse Osmosis and Activated Carbon Adsorption
Ultra filtration/Reverse Osmosis alone will not remove all of the lighter, low molecular weight volatile organisms such as THM`s, TCE, vinyl chloride, carbon tetrachloride, etc. They are too small to be removed by the straining action of the RO membrane. Their chemical structure is such that they aren`t repelled by the membrane surface. Since these are some of the most toxic of the contaminants found in tap water, it is very important that a well designed carbon filter be used before the membrane. In ALL applications with quality RO systems, there is AC after the membrane. This means that post AS filters don`t have to contend with bacteria and all of the other materials which cause fouling and impair performance if AS follows a well maintained membrane.
Not all Ro systems are created equally. That is why you`ll see such variation in price. The engineering and experience behind the RO design is crucial to its overall performance and dependability. NOTE: The typical time required to purify one gallon of RO water is three to four hours. RO uses water to purify water. This is what`s known as the rate of recovery. Superior RO`s use three gallons if brine (waste water) to make one gallon of purified water, and have an automatic shut-off. Some systems have used up to twenty gallons of brine to purify one gallon of product water. Brine is necessary to remove excess accumulated materials from the RO membrane. These materials have been rejected from the purified water, and it left in the system impair efficiency. Our bodies also have a waste water elimination system through the kidneys. If we can`t purge our bodies of these waste materials, WE DIE. Many owners of RO systems direct brine outside and use it in an additional drip line for their gardens, etc. The cost of water energy for fine RO system will amount to about $1.33 per month if one pays for their water at the rate of $1.00 per 100 cubic feet!
Activated Carbon Adsorption
Activated Carbon Adsorption is probably the most widely sold method for home water treatment. This is because of its ability to improve water by removing many disagreeable tastes and odors including objectionable chlorine. Activated Carbon (AC) is processed carbon. In this form it will remove far more contamination from water than will non-activated carbon. AC is made from a variety of carbon based materials such as coal, petroleum, nut shells, and fruit pits. These are heated to high temperatures with steam in the absence of oxygen (the activation process) leaving millions of microscopic pores and great surface area. One pound of activated carbon provides from 60 to 150 acres of surface area. The ores trap microscopic particles and large organic molecules while AC theoretically has the ability to remove or reduce numerous organic chemicals like pesticides, THM`s, TCE, PCB, etc., its actual effectiveness is highly DEPENDENT on the following factors:
- The type of carbon and the amount used.
- The design of the filter and how SLOWLY water flows through it (Contact Time).
- How long the carbon has been in service and how many gallons it has treated.
- The kinds of impurities it has removed.
- The water conditions (e.g. turbidity, temperature, etc.)
One problem with carbon filters is the growth of bacteria. At first, when the carbon us fresh, practically all organic impurities and even some bacteria are removed. Once organic impurities accumulate they can become food for the growth of more bacteria. These can multiply within the filter to great numbers. While these bacteria may not be disease causing, their high concentration is considered by some to present a health hazard. It is often advised that after periods of non-use (such as overnight) a decent quantity of water be flushed through the carbon filter to minimize the accumulation.
Oligodynamic, Silver Impregnated or Bacteriostatic Carbon
A manufacturer who adds (impregnates) silver compounds to the surface of the carbon granules is trying to inhibit bacteria growth within the carbon bed. However, EPA sponsored testing of such filters have shown that they are "neither effective no dependable in meeting these claims" [EPA Report #EPA/600D-86/232 October 1986]. Some manufacturers have also made misleading claims that their silver impregnated filters will eliminate bacterial contamination from virtually any water source. The low concentration of silver found in these filters is not capable of destroying influent waterborne bacteria or providing protection from contaminated water under normal flow conditions. Pyrogens can induce fever (from dead bacteria). Bacteria destroyed in silver impregnated carbon can still end up in your drinking water. Because silver is also toxic to humans, such filters are regulated by the EPA under the Insecticide, Fungicide, and Rodenticide Act and must be registered and issued a registration number. This registration doesn`t imply any EPA approval of the unit or its effectiveness. It does certify that the carbon will not release more than 50 parts per billion of silver - the maximum safe level.
Chemical Recontamination of Carbon Filters
Another problem with carbon filters is chemical recontamination which can occur when the carbon surface has become saturated with the sum total of impurities it has absorbed - a point that is impossible to predict. If the use of the carbon is continued, the trapped organics can release from the surface and recontaminate the water with more impurities than those contained in the raw tap water. To get the most out of carbon, it should be kept scrupulously clean of sediment and heavy organic impurities such as the by-products of decayed vegetable matter and microorganisms. These impurities prematurely use up the carbon`s capacity, preventing it from doing what it does best - adsorbing light weight toxic organic impurities like THM`s and TCE, and undesirable gases such as chlorine.
Solid Block Carbon
This Is obtained when very fine pulverized carbon is compressed and fused together with binding media (such a polyethylene plastic) into a solid block. The intricate maze developed within the block insures contact with organic impurities and therefore more effective removal. The problem of channeling (open paths developing because of the buildup of impurities, and rapid water movement under pressure) in a loose bed of granulated carbon granules is eliminated by solid carbon block filters. Carbon block filters can also be fabricated to have such a fine porous structure that they are capable of mechanically filtering out coli form and other associated disease bacteria. Solid carbon block filters with this feature will require replacement more regularly. Among the disadvantages of compressed carbon filters is the reduced capacity due to the inert biding agent and their tendency to plug up quickly with particulate matter. They are also substantially more expensive than conventional carbon filters.
Limitations of Carbon Filters
A properly designed carbon filter has shown itself capable of removing many toxic organic contaminants, but they fall short of being an overall water treatment system for providing protection from the wide spectrum of impurities which have been referred to in this paper.
They are not capable of removing any of the excess Total Dissolved Solids.
Only a few carbon solid block or carbon matrix systems have been certified for the removal of lead, asbestos, VOC`s, cysts, fecal coli form, and other disease bacteria. Large SUSPENDED materials will be removed by some filters. Small DISSOLVED materials can`t be removed by carbon filtration.
They have no effect on harmful nitrates, or high sodium and fluoride levels.
For any carbon filter to be effective (even for organic removal), water must pass through the carbon (whether it be granular or compressed) slowly enough to insure that complete contact is made between the carbon and the impurities.
THE ALL IMPORTANT FACTOR IS REFERRED TO IN THE INDUSTRY AS CONTACT TIME. At useful flow rates of 0.5 - 1 gallon per minutes, the flow rate is determined by the amount of carbon, and leading manufacturers use the right amount of carbon. One must read carefully the claims which are made by carbon filter companies. Make sure there is a Data sheet to back up their claims. Many companies have certified their water systems with National Sanitation Foundation (NSF). NSF standard protocols are being used by certain states such as California as the model for all systems to be evaluated against. The NSF circle on a product specification sheet demonstrated to the consumer that the product has been tested and verified by NSF and has their certification. Before we leave AC filters, there is another area to be addressed - minerals in drinking water.
Purveyors of AC filter systems usually bring up to the point that "We need minerals in water - these are essential for good health." The only problem with this statement is that there has NEVER BEEN any scientific studies conducted to once and for all PROVE that minerals in water are essential for good health. Frankly, it isn`t a priority in the scientific community to spend the vast amounts of money necessary to conduct the investigation needed to arrive at the conclusion of this issue. Therefore, the value of minerals in drinking water remains a moot point - no one really knows for sure. Everybody may have an opinion regarding this matter - but the fact is that nobody knows for sure. One making a dogmatic statement that "minerals in drinking water are bad, or minerals in drinking water are good" really is showing his/her ignorance of the issues involved. The reason filter dealers bring up this point is because their product will not remove dissolved solids. To keep all of the dissolved minerals requires that one keep all of the total dissolved solids, hardness, and some heavy metals.
---Tony Otero
TGI Pure, CWS II
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