A multi-chamber nitrification reactor for fugate processing, characterized in that it comprises: - a tank which comprises three separate chambers (S1, S2, S3), wherein the chambers have mutually different volumes, wherein the volume of the first chamber is smaller than the volume of the second chamber, which is smaller than the volume of the third chamber, and wherein said tank further comprises an air distribution device connected to a source of compressed air; - a measuring and control unit located outside the tank; - an inlet for raw fugate into each of the tank chambers (S1, S2, S3); - an outlet for the nitrified fugate from each of the tank chambers (S1, S2, S3); - a probe for measuring pH, located inside each chamber (S1, S2, S3) and connected to the measuring and control unit; - a probe (C') for measuring the O 2 concentration, located inside each chamber (S1, S2, S3) and connected to the measuring and control unit; - an inlet for a defoamer in each of the chambers (S1, S2, S3), connected to a pump connected to a container for defoamer; - a neutralization station, located outside the tank, comprising a tank for the pH adjusting agent and a pump, said neutralization station being connected to each chamber (S1, S2, S3) by an inlet for the pH adjusting agent; wherein the pump, and the air distribution device are connected to the measuring and control unit by feedback; and wherein the volume of the first chamber is in the range of from 5 to 10 % of the total reactor tank volume, the volume of the second chamber is in the range of from 20 to 30 % of the total reactor tank volume, and the volume of the third chamber is in the range of from 60 to 75 % of the total volume of the nitrification reactor tank; and wherein the device further comprises a pump configured to pump the liquid content from the first tank chamber to the second tank chamber, and from the second tank chamber to the third tank chamber. - a tank which comprises three separate chambers (S1, S2, S3), wherein the chambers have mutually different volumes, wherein the volume of the first chamber is smaller than the volume of the second chamber, which is smaller than the volume of the third chamber, and wherein said tank further comprises an air distribution device connected to a source of compressed air; - a measuring and control unit located outside the tank; - an inlet for raw fugate into each of the tank chambers (S1, S2, S3); - an outlet for the nitrified fugate from each of the tank chambers (S1, S2, S3); - a probe for measuring pH, located inside each chamber (S1, S2, S3) and connected to the measuring and control unit; - a probe (C') for measuring the O 2 concentration, located inside each chamber (S1, S2, S3) and connected to the measuring and control unit; - an inlet for a defoamer in each of the chambers (S1, S2, S3), connected to a pump connected to a container for defoamer; - a neutralization station, located outside the tank, comprising a tank for the pH adjusting agent and a pump, said neutralization station being connected to each chamber (S1, S2, S3) by an inlet for the pH adjusting agent; wherein the pump, and the air distribution device are connected to the measuring and control unit by feedback; and wherein the volume of the first chamber is in the range of from 5 to 10 % of the total reactor tank volume, the volume of the second chamber is in the range of from 20 to 30 % of the total reactor tank volume, and the volume of the third chamber is in the range of from 60 to 75 % of the total volume of the nitrification reactor tank; and wherein the device further comprises a pump configured to pump the liquid content from the first tank chamber to the second tank chamber, and from the second tank chamber to the third tank chamber.