General information:
The continuity of chlorides in drinking water generally expresses the salinity of drinking water.
Referential after which the analysis is performed:
The analysis of the determination of chlorides at drinking water is performed in its own laboratory according to the standard national SR ISO 9297/2001.
Principle of the method:
Determination of chlorides in drinking water is performed by titrating in the presence of potassium chromate with silver nitrate until the color of the solution is turned into reddish-brown.
Canss of sample rejection – amount of unsuitable sample, samples collected in inappropriate containers, samples not properly labelled, etc.
Recipient – clean container.
The amount of sample required to perform the analysis - minimum 210ml.
Processing required after harvesting – If the pH of the sample is not between 5 and 9,5, adjust using, as the case may be, either nitric acid solution or sodium hydroxide solution, as follows: add 2 or 3 drops of phenoftalein solution and bring it to the turn point of the indicator, with nitric acid or sodium hydroxide solution, as follows: add 2 or 3 drops of phenoftalein solution and bring it to the indicator's turning point, with nitric acid or sodium hydroxide solution, as follows: add 2 or 3 drops of phenoftalein solution and bring it to the indicator's turning point, with nitric acid or sodium hydroxide solution, recording the volume of reagent added. If there are ammonium ions in the sample with concentrations higher than 10 mg/l, adjust the pH between 6.5 and 7. If the pH is less than 5, to improve the buffer capacity, it may be useful to adjust the pH with calcium carbonate.
Sample stability – freshly harvested water is stable for 2 days at 2-8°C or 6 hours at ambient temperature.
The analysis method - volumetrica.
Reference values according to the Water Law1)
Parameter / Unit of measurement | CA value (Maximum permissible concentration) |
|
max. 250 |
2)Water should not be aggressive.
Recommendations for performing the analysis/ Effects of exceeding the reference values –
An excessive and generalized presence of salts in the water is usually found in the waters of great depth, or in those located in coastal areas, due to the infiltrations of marine water. The water has a salty or bitter taste. Excessive salinity makes these waters can not be used in any field, domestic or industrial, due to the chemical aggressiveness that causes corrosion in contact with the metal.
In order to reduce salinity, an installation with reverse osmosis is used, composed of semipermeable membranes that can reduce the amount of salts in a percentage between 70-58%, while the water with residual saline concentration is thrown at the channel.
Bibliography:
- LEGEA 458/2002 as amended and supplemented by Law no. 311/2004, Government Ordinance no. 11/2010, Law no. 124/2010 and Government Ordinance no. 1/2011