Nitrates / Nitrites
Nitrates (NO3)- and nitrites (NO2)- occurs naturally in outside environment and are a part of the nitrogen cycle. Nitrites are widely used as a industrial fertilizers, oxidation reagents in production of expolsives , for potassium purification in glass production . In the food industry, nitrates and nitrites are used as a stabilizers and preservatives. Nitrites can be found in surface and/or groundwaters as a result of agricultural activity.
Nitrates belong among the highly monitored substances, which are due to its toxicity, or more precisely due to its chemical conversion into the toxic nitrites, harmful to adults and especially to children. Hazard which nitrates represent, is that they are the subject to change in toxic nitrites in the human digestion system. Nitrites further react with haemoglobin to form methaemoglobin, which is not able to transfer the oxygen and causes the nitrite alimentary methaemoglobinaemia (DAM), the condition especially hazardous for infants and small children. Therefore, nitrate content is limited in the infant drinking water production to 15 mg/l. For adults the limit value is 50 mg/l.
There is a simmilar process for nitrate removal (denitrification) as it is for water softening, when a water flows thru the ion exchange resin filling, which is going to be anex in this case. As in the water softening process, after decreasing its ion exchanging capacity, the resin filling needs to be regenerated with natrium chloride solution.