Vrut: Importing text file

2014-07-14T23:05:13Z

Importing text file

Nová stránka

:Slovak term: [[Slovenský termín]]
# The pH of a solution is the negative common logarithm of the hydrogen ion activity:<br />pH = −log (H+) (WHO 2007)
# An expression of the intensity of the basic or acid condition of a liquid (WHO 2006).

==Explanation==
Most substances have a pH in the range 0 to 14, although extremely acidic or extremely
basic substances may have pH less than 0 or greater than 14.
The pH of water is a measure of the acid-base equilibrium and, in most natural waters, is
controlled by the carbon dioxide-bicarbonate-carbonate equilibrium system (WHO 2007).
An increased carbon dioxide concentration will therefore lower pH, whereas a decrease
will cause it to rise. Temperature will also affect the equilibria and the pH. In pure water, a
decrease in pH of about 0.45 occurs as the temperature is raised by 25°C. In water with a
buffering capacity imparted by bicarbonate, carbonate and hydroxyl ions, this temperature
effect is modified. The pH of most raw water lies within the range 6.5-8.5.
pH is an important consideration in the management/controlling of disinfection by-product
formation arising from treatment processes (Amy et al. 1987 and Stevens et al. 1976).

==Example==
Although pH usually has no direct impact on water consumers, it is one of the most
important operational water quality parameters. Careful attention to pH control is
necessary at all stages of water treatment to ensure satisfactory water clarification and
disinfection. For effective disinfection with chlorine, the pH should preferably be less than
8.0. The pH of the water entering the distribution system must be controlled to minimize
the corrosion of water mains and pipes in household water systems. Failure to do so can
result in the contamination of drinking-water and in adverse effects on its taste, odour and
appearance.

==References==
* Amy, G.L., Chadik, P.A., and Chowdhury, Z.K. (1987) Developing models for predicting trihalomethane formation potential and kinetics. J. Am. Water Works Assoc., 79: 89.
* Stevens, A.A., Slocum, C.J., Seeger, D.R., and Robeck, G.G. (1976) Chlorination of organics in drinking water. J. Am. Water Works Assoc., 68: 615.
* WHO (2007) [http://www.who.int/water_sanitation_health/dwq/chemicals/pH/en/ pH in Drinking-water: Revised background document for development of WHO Guidelines for Drinking-water Quality.]
* WHO (2006) [http://www.who.int/water_sanitation_health/wastewater/gsuww/en/index.html Guidelines for the safe use of wastewater, excreta and greywater]

==Links==
* [http://apps.who.int/thelexicon/ WHO — The Health and Environment Lexicon]
* WHO (1996) [http://www.who.int/water_sanitation_health/dwq/gdwq2v1/en/index1.html Guidelines for drinking-water quality. Volume 2: Health criteria and other supporting information.]

[[Category:EN]]

PH (eng) - História úprav

Vrut: Importing text file