Water (in its pure form) is a tasteless, odorless substance that is essential to all known forms of life and is known as the universal solvent. It appears colorless to the naked eye in small quantities, though it can be seen to be blue with scientific instruments or in large quantities (as in a swimming pool). Clean water is essential to human health and in many parts of the world it is in short supply .
Chemical and physical properties
Water has the chemical formula H2O meaning that one molecule of water is composed of two hydrogen atoms and one oxygen atom. It can also be described ionically as HOH, with a hydrogen ion (H+) that is bonded to a hydroxide ion (OH-). It is in dynamic equilibrium between the liquid and vapor states at standard temperature and pressure. At room temperature, it is a nearly colorless, tasteless, and odorless liquid. It is often referred to in the sciences as the universal solvent and the only pure substance found naturally in all three states of matter.
Color
Water strongly absorbs infrared radiation. As infrared radiation is next to red-colored light on the EM spectrum, a small amount of visible red light is absorbed as well. This results in pure water appearing slightly blue, when seen in mass quantities such as a lake or ocean. The blue color can easily be seen as one sees the blue color of the sea or a clear lake under an overcast sky, which means that it is not a reflection of the blue sky.
In practice, the color of water can vary strongly, depending on impurities. Limestone turns bodies of water turquoise, while iron compounds turn it red/brown and copper compounds create an intense blue. Algae commonly colors water green.
Solvation
Water is a very good solvent, dissolving many types of substances. The substances that will mix well and dissolve in water (e.g. salts) are known as "hydrophilic" (water-loving) substances, and those that do not mix well with water (e.g. fats and oils), are known as "hydrophobic" (water-fearing) substances. Whether a substance dissolves or not is decided by whether or not the substance can match or better the strong attractive forces that water molecules generate between themselves. If they cannot, the molecules are "pushed out" from amongst the water, and do not dissolve. Substances dissolved in water are referred to as "aqueous".
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Life forms that live in water
Earth's waters are filled with life. Fish live exclusively in water, and there are many types of marine mammals, such as dolphins and whales that also live in the water. Some types of animal, such as amphibians spend portions of their lives in water, and portions on land. Plants such as kelp and algae grow in the water, and are the basis for some underwater ecosystems. Plankton, however, is generally the foundation of the ocean food chain.
Different water creatures have found different solutions to obtaining oxygen in the water. Fish have gills instead of lungs, though some species of fish, such as the lungfish have both. Marine mammals, such as dolphins, whales, otters, and seals need to surface periodically to breathe air. |
Human uses of water
Water pressure in a sprinkler |
A leaking tap |
Humans use water in typically three variety of ways:
For drinking - About 72% of the fat free mass of the human body is made of water. To function properly, the body requires between one and seven liters of water per day to avoid dehydration, the precise amount depends on the level of activity, temperature, humidity, and other factors. Most of this is ingested through foods or beverages other than drinking straight water (hot tea being often used in deserts to avoid dehydration, etc.) It is not clear how much water intake is needed by healthy people.
Humans require water that does not contain too many impurities. Common impurities include metal salts and/or harmful bacteria, such as vibrio. Some solutes are acceptable and even desirable for perceived taste enhancement and to provide needed electrolytes.
As a solvent - Water is a good solvent, dissolving (or suspending) is used to wash everything from the human body, clothes, floors, cars, food, pets, and just about anything and everything in between. Sometimes water is not enough, and many chemicals can be added in order to improve the solvating power of water. These chemicals include soap, shampoo, alcohol, vinegar and various surfactants; these are all examples of emulsifying agents. When water will not do (e.g. removing a none water-soluble substance such as paint), other solvents are used, such as ethanol (in meths) or acetone (in nailvarnish remover).
As a thermal transfer - Boiling, steaming, and simmering are popular cooking methods that often require immersing food in water or its gaseous state, steam. Water is also used in industrial contexts, as a coolant during metallurgy, and in almost all power stations as a coolant and to drive steam turbines to generate electricity. In the nuclear industry, water can also be used as a neutron moderator.
Recreational use of water
Humans use water for many recreational purposes, as well as for exercising and for sports. Some of these include swimming, waterskiing, boating, skiing, fishing, and diving. In addition, some sports, like hockey and ice skating, are played on ice.
Lakesides and beaches are popular places for people to go to relax and enjoy recreation.
Drinking water from a tap. |
Health and pollution
Water fit for human consumption is called drinking water or "potable water". Water that is not specifically made for drinking, but is not harmful for humans when used for food preparation is called safe water.
This is why drinking water must be free of any chemicals , toxic metals , bacterial and parasitic contamination .But because of the chemicals and toxic wastes which are poured in rivers and lakes ; contaminants sources of drinking water are resulted .
Watermust provides a suitable solution to overcome this problem by using filters …
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General idea of filters :
A water filter is composed of a screen with many microscopic holes which are measured in microns; the smaller the holes the more sediment the filter can remove.
Thus water can be divided to several types according to the amounts of total dissolved solids (TDS) :-
• Fresh water :<1000 TDS
• Brackish water : 1000 – 5000 TDS
• Highly brackish water : 5000 – 15,000 TDS
• Saline water : 15,000 – 30,000 TDS
• Sea water : 30,000 – 40,000 TDS
• Brine : 40,000 – 300,000+ TDS
Now amounts of salts (TDS) can be controlled i.e. varies according to the health conditions.
Types Of Filtration Media :-
1- KDF – 55 :-
• Is a high purity Copper-Zinc alloy .
• Used to kill bacteria , viruses , reduction of heavy metals and chlorine .
• KDF-55 pretreatment for heavy metals removal to reduce membrane damage and elongate membrane element duration life .
2- Granular Activated Carbon (GAC) :-
• Adsorption of chlorine chemicals, tastes , odors and pesticides .
3- Silver Impregnated Activated Carbon (SIAC) :-
• For reduction of chlorine, chemicals, tastes, odors and killing of any bacteria and viruses.
4- Birm :-
• For iron removal.
5-Anthracite:-
• For sediment and turbidity removal.
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