Water is the most essential ingredient of human life. Our bodies consist of 66% water, and we drink around 2 liters every day!

Yet not everybody in the world has access to good quality water. Some shocking statistics indicate just how much of an issue unsafe water is all over the world: around 1.1 billion people do not have access to safe drinking water! Overall an estimated 900 million people suffer and approximately 1.8 million die from water-related diarrhoeal illnesses each year – the vast majority of which is concentrated on children in developing countries.

About water treatment

Numerous techniques, processes and products are available for treating water. Systems and products have been developed on various different scales; from complex treatment plants for industrial and municipal use, to portable and disposable products for personal use. All these systems use combinations of technologies and processes that are suitable for the type of raw water that is being treated.

Basic treatment

For raw waters of very poor quality processes such as screening, sedimentation, aeration and flotation are often used to remove the bulk of contaminants. Further treatment then involves techniques that are also used on slightly better quality source water. Chemical treatments such as coagulation and flocculation are used to clarify water and remove solids. Next, a wide range of filtration techniques can be employed.

Filtration and activated carbon

Filtration media that are often used include sand, diatomaceous earth (DE), fibrous materials such as textiles or polymers, ceramics, and activated carbon (AC). Activated carbon is very popular because of the added effectiveness of its ability to adsorb certain chemicals. It comes in the form of powder, granules or blocks, and is often used in common filter cartridges. Well-known applications include the filter cartridges used in the AquaDoc UV and kettle-type filters used in many households.

AC has the ability to improve the taste and odour of water, and to remove chemicals such as certain pesticides and chlorine. A major disadvantage of AC is that it is known to accommodate the growth of bacteria and other microbes and release them into product water. Therefore, wherever AC is used in a water treatment system it should be maintained properly and if necessary followed by effective disinfection of the water.

Reverse osmosis

Specialised water treatment can involve the use of membrane filtration or reverse osmosis (RO). These processes use very thin films (membranes) that allow water to pass through while blocking even the smallest of particles. RO works by applying pressure to contaminated water on one side of the membrane to push only the water through while retaining everything else behind it. This process produces very pure water, without any of its natural constituents. This water is mostly used in industrial processes and laboratory environments. However, in recent years RO devices have become very popular for home water purification. This is a controversial development because it has been shown that drinking highly pure water poses a health risk, due to the lack of minerals, electrolytes and other desirable substances present in natural water.

Water test scam

It has come to light that sales people from various water treatment companies have been using an electric precipitator test to supposedly show that only RO water is clean. This is a serious scam to trick people into buying their product. It is based on an outright lie and uses the reduced ability of RO water to conduct electricity to make normal water look dirty. To read more, or to share your experience, click here. Do not let yourself be fooled!

Disinfection

In most cases disinfection is the most important process for the supply of safe drinking water. Common methods of disinfecting water include boiling, the use of chemicals such as chlorine and ozone, and ultraviolet radiation. Chlorination is perhaps the best known method as it is often used for treating water in swimming pools. It involves the application of a high dose of chlorine, chloramines or chlorine dioxides, in the form of powders, tablets or liquids. Chlorine is very effective in killing many microbes and leaves a residual effect that can keep the water safe for a long time. Another advantage is that by saturating the chlorine demand of the water a leverage is created that can cover for variations in the water quality. Disadvantages of chlorination include objectionable taste and odour, and the possible formation of harmful by-products.

Disinfection using ozone is a more specialised process, because it involves the production and application of the dangerous gas that is ozone. Like chlorination it is also very effective in inactivating many pathogens, but unlike chlorine it does not have much of a residual effect. Small point-of-use ozone treatment systems are available, but they are generally hard to maintain and expensive. Therefore it is more often used on a central level, where specialised equipment and skilled operators are available.

Ultraviolet disinfection

Ultraviolet (UV) disinfection works by passing high-intensity UV radiation through water. UV radiation destroys microbes by inactivating their genetic materials (RNA or DNA). Sunlight contains some UV light and can thus be used for disinfection. The effectiveness of solar treatment depends on the intensity of the sun and the water temperature; it often takes very long for solar disinfection to have any useful effect. In professional UV water treatment products high intensity lamps are used that provide a strong dose of UV radiation to disinfect the water. Advantages of UV disinfection are that it is very effective in inactivating all kinds of pathogens, does not change the chemical constitution of the water, and leaves no taste or odour. A disadvantage is that it does not provide a residual effect.

UV technology

Ultraviolet (UV) disinfection works by passing high-intensity UV radiation through water. UV radiation destroys microbes by inactivating their genetic materials (RNA or DNA).

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Water treatment

Numerous techniques, processes and products are available for treating water. All these systems use combinations of technologies and processes that are suitable for the type of raw water that is being treated.

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