Importance, Composition, Properties and Contaminants of Water

1. Water composition and molecular structure
* It consists of 2 hydrogen atoms and one oxygen atom, and each hydrogen atom is attached to oxygen with a single covalent bond.
* The length between the two hydrogen nuclei is very small and the molecule is not linear, it has the shape of almost a tetrahedron with an angle of 105 ° between the H.
* This structure makes it polar, that is, it has a lot of negative charge accumulated at one end and little negative charge at the other end or positive pole.
* It has great stability against heat, only 1% decomposes at temperatures higher than 1100 ° C.
* If it is pure it does not conduct electricity, but if we add an acid or a base it easily conducts electric current.
Polarity and hydrogen bridges.

* Polarity. It is when a molecule has opposite but separate charge centers and this property helps us to classify organic solvents: The higher the polarity, the higher the dissolution power.
* Hydrogen bonds. It is not a true bond but an electrostatic attraction between a proton and a pair of electrons of a small atom like: O, N or P and this It gives a special behavior to the substance that presents it, which is soluble in water as it forms hydrogen bonds with the molecule of Water.

5. Solutions.
A solution It is a homogeneous mixture, with components of uniform distribution, composed of solute and solvent.
Solute and solvent concept.
Solute It is the component that dissolves within the solvent and generally goes in less quantity.
Solvent Medium in which solute dissolves and is generally more abundant in solution.
6. Water contamination.
Main pollutants: physical, chemical and biological.
* Wastewater and other waste that demand oxygen (mostly organic matter, whose decomposition produces the deoxygenation of the water).
* Infectious agents
* Plant nutrients that can stimulate the growth of aquatic plants. These, in turn, interfere with the uses to which the water is put and, by decomposing, deplete dissolved oxygen and produce unpleasant odors.
* Chemicals, including pesticides, various industrial products, substances surfactants contained in detergents, and the decomposition products of other compounds organic.
* Oil, especially from accidental discharges.
* Inorganic minerals and chemical compounds.
* Sediments formed by soil particles and minerals carried by storms and runoff from farmland, unprotected soils, mining operations, roads and debris urban.
* Radioactive substances from waste produced by mining and refining of the uranium and tone, nuclear power plants and the industrial, medical and scientific use of materials radioactive.
* Heat can also be considered a pollutant when the discharge of the water used for the Cooling factories and power plants raises the temperature of the water from which they are they supply.
Generating sources: industrial, urban and agricultural.
Urban pollution is made up of wastewater from homes and commercial establishments. For many years, the main objective of municipal waste disposal was only to reduce its content in materials that demand oxygen, suspended solids, dissolved inorganic compounds (especially phosphorus and nitrogen compounds) and bacteria pathogens. In recent years, on the contrary, more emphasis has been placed on improving the means of eliminating solid waste produced by purification processes. The main urban wastewater treatment methods have three phases: primary treatment, which includes grit removal, filtration, grinding, flocculation (aggregation of solids), and sedimentation; secondary treatment, which involves the oxidation of dissolved organic matter by means of biologically active sludge, which is then filtered; and tertiary treatment, in which advanced biological methods are used to eliminate the nitrogen, and physical and chemical methods, such as granular filtration and carbon adsorption activated. The handling and disposal of solid waste represents between 25 and 50% of the capital and operating costs of a treatment plant.
The characteristics of industrial wastewater can differ greatly both within and between companies. The impact of industrial discharges depends not only on their common characteristics, such as the biochemical oxygen demand, but also its content in organic and inorganic substances specific. There are three options (which are not mutually exclusive) to control industrial discharges. Control can take place where plant tooth is generated; the waters can be previously treated and discharged into the urban purification system; or they can be completely purified at the plant and reused or simply discharged into streams or bodies of water.
Agriculture, commercial livestock, and poultry farms are the source of many organic and inorganic pollutants in surface and groundwater. These pollutants include both sediments from cropland erosion and Phosphorous and nitrogen compounds that, in part, come from animal waste and fertilizers commercial. Animal waste is high in nitrogen, phosphorus, and oxygen-consuming matter, and often harbor pathogenic organisms. Factory hatchery wastes are disposed of on land by containment, so the main danger they pose is that of seepage and runoff. Control measures may include the use of settling tanks for liquids, limited biological treatment in aerobic or anaerobic lagoons, and a host of additional methods.
7. Importance and applications of water for humanity.
* Water has many different uses, it is simply necessary for maintenance of life since living beings have an important percentage composition in water.
* Water is the universal thermoregulator, the seas help to conserve the temperature of the earth so that it is appropriate for life.
* Also, water is a universal solvent and vehicle for many organic substances.
* There are almost no activities of humanity that do not use water directly or indirectly.
8. Responsible use and preservation of water.
Water, being a vital liquid, must be used wisely and strictly for needs.