U ovom radu provedeni su pokusi uklanjanja sastojaka s dušikom iz otpadne vode rafinerije nafte primjenom procesa nitrifikacije i denitrifikacije. Za uklanjanje sastojaka s dušikom uporabljena je mješovita kultura sastavljena od odabranih sojeva bakterija kao tročlana mješovita kultura i obogaćena tročlana kultura s dva dodatna bakterijska člana podrijetlom iz otpadne vode rafinerije (OMBK-NI/DNI). Pokusi su provedeni pri odabranim čimbenicima okoliša: pH-vrijednost, koncentracija otopljenog kisika, temperatura i koncentracija biomase. Pokusi nitrifikacije i denitrifikacije motreni su određivanjem koncentracije amonijakalnog, nitratnog, nitritnog dušika i pH-vrijednosti. Postupnom prilagodbom OMBK-NI/DNI na otpadnu vodu rafinerije, dokazana je aktivnost za uklanjanje sastojaka sa dušikom iz otpadne vode procesima nitrifikacije i denitrifikacije pri odabranim čimbenicima okoliša. Kao izvor ugljika za odvijanje procesa denitrifikacije uporabljen je natrij-acetat u omjeru C:N=1.5:1. Provedbom pokusa nitrifikacije otpadne vode rafinerije pomoću OMBK-NI/DNI nakupljao se nitrat i nitrit, dok je provedbom pokusa denitrifikacije nitrificirane otpadne vode rafinerije postignuto 100%-tno uklanjanje nitrita i preko 70% uklanjanje nitrata.

In these work experiments of nitrogen removal from petrol industry, wastewaters were invastigated using processes of nitrification and denitrification. When removing nitrogen compounds, mixed culture consisting of chosen strains of bacteria as trinominal culture with two added bacteria strain origin from refinery wastewater (OMBK-NI/DNI) were used. Experiments were performed under selected environmental parameters: pH, concentration of soluble oxygen, temperature and concentration of biomass. In the processes of nitrification and denitrification concentrations of ammonium, nitrate, nitrite and pH were determined. In the gradual adaptation of OMBK-NI/DNI on refinery wastewater, the activity was established for nitrogen removal from wastewaters by agency of processes nitrification and denitrification under environmental conditions. Sodium-acetate was used as carbon source in ratio C:N=1.5:1 for denitrification process. During the nitrification process with OMBK-NI/DNI nitrite and nitrate were accumulated, while during the denitrification process, 100% of nitrite removal was achieved, and more than 70% removal of nitrate.