BIOLOGICAL WATER TREATMENT PROCESS AND PLANT USING ACTIVATED SLUDGE WITH REGULATION OF AERATION

The invention relates to a method and installation for the biological treatment of water using activated sludge or mixed cultures, including the aeration of the activated sludge tank. The inventive method consists in: (a) fixing the times for the aeration (T1min and T1max) and non-aeration (T2min and T2max) periods, high (SHNO3) and low (SBNO3) set values for the nitrate concentration of the treated water or the mixed liquor, and a high set value for the redox potential (SH redox) of the water present in the tank; (b) continuously measuring the aeration (T1) and non-aeration (T2) times, the nitrate levels in the treated water or the mixed liquor, and the redox potential of the mixed liquor, and not aerating the mixed liquid either (i) when the nitrate concentration is less than SB NO3 and T2 is less than T2min or (ii) when the nitrate concentration is greater than SB NO3 but T2 has not reached time T2max; and (c) aerating the mixed liquor either (i) when the measured nitrate concentration is greater than SH NO3, (ii) when the measured redox potential value is greater than SH redox and T1 is less than T1min, (iii) when the nitrate concentration is less than SH NO3, or (iv) when the oxidation-reduction potential value is less than SH redox but T1 has not reached T1max.