Environmental contamination by nitrates is becoming in recent years a particularly relevant dimension because of the progressive and uncontrolled increase of their presence in the soil and both surface and deep water.
The limit value of the concentration of nitrates in drinking water beyond which it is advisable to provide for the installation of a denitrification is equal to 50 mg / L (NO3). Above this concentration water can not be considered potable. However, even the tap water, while presenting the chemical-physical and microbiological fit for human consumption may contain nitrate ions in sufficient concentration to give water a corrosive tendency to many metals that make up a plumbing distribution of drinking water.
Therefore, to reduce the nitrate content in water or, otherwise, to bring the nitrate concentration within the limits allowed by law can provide for the installation of denitrification.
Denitrificators are fully automatic equipment that are based on the denitrification process by ion exchange or using anionic resins with selective action capable of retaining the nitrates present in the water, replacing them with chloride ions.
Even in this case, the resins are periodically “exhausted” and it is therefore necessary to perform the regeneration with a solution of sodium chloride (salt) to restore the regular capacity of the resins.