General information:
The iron appears naturally in the depth waters in three forms: Iron Ferura (the water is clear), Feric Iron (red water) and Red organic complex containing iron (Organic Iron).
Referential after which the analysis is performed:
The analysis for determining the iron content of drinking water is performed within its own laboratory according to the national standard SR 13315:1996 +C91:2008.
The principle of the method:
Determination of iron content in drinking water is performed by the spectroscopy method of atomic absorption in flame.
Canuses of sample rejection – quantity of unsuitable sample, sample collected in inappropriate containers, samples not properly labeled, etc.
Recipient of collection – clean container, before sampling, the container after being washed normally, is washed with nitric acid d = 1.4 diluted 1+1 and then with water.
The amount of sample required to perform the analysis - minimum 100ml.
Processing required after collection – Samples, of about 1L, are taken in glass or plastic containers. The determination of iron is performed on samples filtered by filter paper with medium porosity, washed with nitric acid d = 1.4 taken 1+1. (NOTE – If it is also interested in the iron content of the suspensions, the samples are not filtered before preservation.). The preservation of the samples is done by adding nitric acid d = 1.4 to pH = 1... 3, and another 2 ml for each liter of sample.
Sample stability – freshly harvested water is stable for 2 days at 2-8°C or 6 hours at ambient temperature.
The analysis method –spectroscopy of atomic absorption in flame.
Reference values according to water law1)
| Parameter / Unit of measurement | CA value (Maximum permissible concentration) |
| Fier, μg/L | 200 |
Recommendations for performing the analysis/ Effects of exceeding the reference values –
The iron appears naturally in the waters of depth in three forms: Iron Ferura (water is clear), Ferric Iron (red water) and Red organic complex containing iron (Organic Iron).
Each state may be present alone but also in combination with the others. Iron in the first form is also called ferrous bicarbonate. The water is clear when it is fresh but becomes cloudy in contact with the air. The air oxidizes the iron ferura and transforms it into Feric iron or ferric hydroxide, which is visible in fresh water and is red in color. Organic iron is a combination of decomposed vegetation and iron. These organic matter are the cause of the reddish color of water. Certain bacteria feed on iron. They oxidize iron from the ferrous into the ferric and store it in a gelatinous mass with which it surrounds. These gelatinous formations are dangerous because they can block valves and filter media.
For reducing the iron content of the water, special deferization installations are often used.
Bibliography:
- LEGEA 458/2002 with subsequent amendments and completions Law no. 311/2004, Government Ordinance no. 11/2010, Law no. 124/2010 and Government Ordinance no. 1/2011
