NOX Process

NOx processes is a new possi-bility of stimulating and controlling the activ-ity of the Nitrosomonas-like microorganisms by the addition of nitrogen oxides. The Nitrosomonas strains have a versatile metabolism and are able to gain energy during the aerobic and anaerobic ammonia oxidation or by denitrification using hydrogen or organic compounds as electron donors.The anaerobic ammo-nia oxidation by Nitrosomonas is dependent on the nitrogen dioxide (NO2). The conversion of about 50% of the ammonia load to nitrite occurs and the nitrite produced is used as a terminal electron acceptor, which leads to N2 production.The Nitro-somonas eutropha consumes ammonia and NO2 at the ratio of approximately 1:1.An equivalent amount of NO is produced. Then, during denitrification of nitrite to N2 small amounts of N2O are produced. Trace amounts of gases NO and NO2 (NOx) can be added to induce a short-ened nitrification/denitrification route by Nitrosomonas and can therefore be the regula-tory signal for the denitrification activity. NO2 concentrations of up to 50 ppm have no toxic effects on Nitrosomonas eutropha but NO at concentration above 25 ppm inhibit the ammonia oxidation.
Consequently, in the NOx process, the nitrifi-cation part is more efficient due to a 50% lower oxygen demand whereas the following step demands up to 80% less organic matter for denitrification.There is a possibility of implementing this process in the existing treatment facilities with minimal financial efforts and minor changes in the operation strategy.
3NH4++3O2+3[H] → 1.5N2+3H++6H2O