Consideration regarding treatment possibilities of drinking water supplies containing nitrogen compounds

Abstract

The paper presents some relevant aspects related to the influence of pollution matrix specific to the groundwater supplies, upon the treatment technologies applied in order to remove the inorganic nitrogen - based compounds (ammonium, nitrite, nitrate ions). The main association of ammonium (NH4+) with inorganic/organic pollutants in groundwater are, as follows:  NH4+ and metallic ions (Mn  Fe);  NH4+ and sulphur derivatives (S2-, S2O32-, SO32-);  NH4+ and nitrite/nitrate ions (NO2-/ NO3-);  NH4+ and natural organic matter (NOM - THMs precursors) in the presence of bromide ion (Br-). Also, the concentration levels of nitrogen - based compounds and associated pollutants are very important in the selection of suitable treatment procedures, including the succession of treatment steps. The treatment technologies developed for NH4+ and NO3- ions removal from groundwater supplies have as specific steps: breakpoint chlorination (NH4+) or biological nitrification (NH4+) and denitrification (NO2-/ NO3-) processes. Among the main problems specific for the most applied technology at industrial level for NH4+  oxidizable pollutants removal (one step chlorination), are mentioned:  low treatment efficiency (NH4+, S2-);  generation of trihalometanes (THMs), especially brominated ones, with unpleasant consequence upon the treated water quality, which is not proper for human consumption.