طرق معالجة لمياه من التلوث البكتيرى باستخدام الاشعة فوق البنفسجية/فلاتر الاوزون/الدايونيزر/فلاتر الخارصين

Water disinfection treatment methods
Ultra Violet Light:
Water passes through a clear chamber where it is exposed to Ultra Violet (UV) Light. UV light effectively destroys bacteria and viruses. However, how well the UV system works depends on the energy dose that the organism absorbs. If the energy dose is not high enough, the organism’s genetic material may only be damaged rather than disrupted.
The advantages of using UV include:
No known toxic or significant nontoxic byproducts introduced
Removes some organic contaminants
Leaves no smell or taste in the treated water
Requires very little contact time (seconds versus minutes for chemical disinfection)
Improves the taste of water because some organic contaminants and nuisance microorganisms are destroyed

Many pathogenic microorganisms are killed or rendered inactive.
Does not affect minerals in water
The disadvantages of using UV include:
UV radiation is not suitable for water with high levels of suspended solids, turbidity, color, or soluble organic matter. These materials can react with UV radiation, and reduce disinfection performance. Turbidity makes it difficult for radiation to penetrate water and pathogens can be 'shadowed', protecting them from the light.



UV light is not effective against any non-living contaminant, lead, asbestos, many organic chemicals, chlorine, etc.

Tough cryptosporidia cysts are fairly resistant to UV light.
Requires electricity to operate. In an emergency situation when the power is out, the purification will not work.

UV is typically used as a final purification stage on some filtration systems. If you are concerned about removing contaminants in addition to bacteria and viruses, you would still need to use a quality carbon filter or reverse osmosis system in addition to the UV system.
Water Softeners and deionizers:
Water softeners operate on the ion exchange process (specifically a cation exchange process where + ions are exchanged). In this process, water passes through a media bed, usually sulfonated polystyrene beads. The beads are supersaturated with sodium (a positive ion). The ion exchange process takes place as hard water passes through the softening material. The hardness minerals (positively charged Calcium and Magnesium ions) attach themselves to the resin beads while sodium on the resin beads is released simultaneously into the water. When the resin becomes saturated with calcium and magnesium, it must be recharged. The recharging is done by passing a concentrated salt (brine) solution through the resin. The concentrated sodium replaces the trapped calcium and magnesium ions which are discharged in the waste water. Softened water is not recommended for watering plants, lawns, and gardens due to its elevated sodium content.
Several factors govern the efficiency of a cationic softener:
Type & quality of resin used;
Amount of salt per cubic foot of resin for regeneration;
Brine concentration in the resin bed during regeneration;
Brine flow rate through the resin bed (contact time) during regeneration;
Raw water hardness;
Raw water temperature - softeners perform better at higher temperatures; and
Optimal flow rate of hard water through the resin bed.
Although not commonly used, potassium chloride can be used to create the salt brine for softeners designed to use KCl. In that case potassium rather than sodium is exchanged with calcium and magnesium. Before selecting an ion exchange water softener, test water for hardness and iron content. When selecting a water softener, the regeneration control system, the hardness removal capacity, and the iron limitations are three important elements to consider
The advantages of water softeners include:
The nuisance factor of hard water is reduced.
some other other cations like barium, radium and iron may be reduced depending on the manufacturer's specifications.

The disadvantages of water softeners include:
The process of regenerating the ion exchange bed dumps salt water into the environment.

The elevated sodium concentration of most softened water can affect the taste and may not be good for people on low sodium diets, although sodium concentrations are typically quite low relative to sodium levels in most food.

Cation exchange does not reduce the level of anions (like nitrates), or biological contaminants (bacteria, viruses, cysts) ; nor does the process reduce the levels of most organic compounds.


Typically, approximately 50 gallons of rinse water per cubic foot of resin is required to totally remove hardness and excess salt from the resin after each regeneration.


Water Deionizers use both Cation and Anion Exchange to exchange both positive and negative ions with H+ or OH- ions respectively, leading to completely demineralized water. Deionizers do not remove uncharged compounds from water, and are often used in the final purification stages of producing completely pure water for medical, research, and industrial needs.
A potential problem with deionizers is that colonies of microorganisms can become established and proliferate on the nutrient-rich surfaces of the resin. When not regularly sanitized or regenerated, ion-exchange resins can contaminate drinking water with bacteria.
KDF "Filters":
KDF filters employ a matrix (generally small granules) of a zinc/copper alloy, which allegedly eliminates contaminants from water by utilizing electrochemical oxidation reduction. Chemical properties of KDF include its alleged ability to:
Remove chlorine (actually changes free chlorine to a less active form)
Kill algae and fungi
Control bacterial growth in the filter
Remove hydrogen sulfide, iron, lead, cadmium, aluminum, mercury, arsenic and
other inorganic compounds
Partially reduce hardness
Zinc and copper are the preferred metals used in the KDF alloy since both are relatively good reducing agents with respect to common inorganic contaminants (such as chlorine), and both can be tolerated in solution in moderate concentrations without adverse side effects.
The advantages of KDF filters include:
KDF is the only filter medium I am aware of that allegedly removes contaminants from running hot water (unlike carbon filters where hot water can release trapped contaminants into the water stream). This makes them ideal for use in the shower.


The filters change the free chlorine some people are allergic to into a form (zinc c chloride) that is much more easily tolerated.

The disadvantages of KDF filters include:
KDF filters do not, by themselves, remove organic chemicals (pesticides, disinfection byproducts, MTBE, etc.), or parasitic cysts (giardia and cryptosporidium). If you are concerned about removing any of these contaminants, other strategies will be needed in addition to the KDF media.



KDF filters need to be backwashed periodically with hot water to remove the
insoluble contaminants. This method wastes many gallons of hot water and there is no way to prevent dislodged pollutants from coming out later with the supposedly filtered water.

Ozonation:
The formation of oxygen into ozone occurs with the use of energy. This process is carried out by an electric discharge field as in the CD-type ozone generators (corona discharge simulation of the lightning), or by ultraviolet radiation as in UV-type ozone generators (simulation of the ultra-violet rays from the sun). In addition to these commercial methods, ozone may also be made through electrolytic and chemical reactions.
Ozone is a naturally occurring component of fresh air. It can be produced by the ultraviolet rays of the sun reacting with the Earth's upper atmosphere (which creates a protective ozone layer), by lightning, or it can be created artificially with an ozone generator.
The ozone molecule contains three oxygen atoms whereas the normal oxygen molecule contains only two. Ozone is a very reactive and unstable gas with a short half-life before it reverts back to oxygen. Ozone is the most powerful and rapid acting oxidizer man can produce, and will oxidize all bacteria, mold and yeast spores, organic material and viruses given sufficient exposure.
The advantages of using Ozone include:
Ozone is primarily a disinfectant that effectively kills biological contaminants.
Ozone also oxidizes and precipitates iron, sulfur, and manganese so they can be filtered out of solution.

Ozone will oxidize and break down many organic chemicals including many that cause odor and taste problems.

Ozonation produces no taste or odor in the water.
Since ozone is made of oxygen and reverts to pure oxygen, it vanishes without trace once it has been used. In the home, this does not matter much, but when water companies use ozone to disinfect the water there is no residual disinfectant, so chlorine or another disinfectant must be added to minimize microbial growth during storage and distribution.


The disadvantages of using Ozone include:
Ozone treatment can create undesirable byproducts that can be harmful to health if they are not controlled (e.g., formaldehyde and bromate).

The process of creating ozone in the home requires electricity. In an emergency with loss of power, this treatment will not work.

Ozone is not effective at removing dissolved minerals and salts.
Caution - The effectiveness of the process is dependent, on good mixing of ozone with the water, and ozone does not dissolve particularly well, so a well designed system that exposes all the water to the ozone is important.
In the home, ozone is often combined with activated carbon filtration to achieve a more complete water treatment.
Activated Alumina:
Activated Alumina is a granulated form of aluminum oxide. In this process, water containing the contaminant is passed through a cartridge or canister of activated alumina which adsorbs the contaminant. The cartridge of activated alumina must be replaced periodically. Activated alumina devices can accumulate bacteria, so treated water may have higher bacteria counts than raw water.
The advantages of Activated Alumina filters include:
An effective way to reduce levels of fluoride, arsenic, and selenium
The disadvantages of Activated Alumina filters include:
The use of other treatment methods would be necessary to reduce levels of other contaminants of health concern