A wastewater treatment method. The method includes establishing a setpoint value of oxidation-reduction potential of a mixed liquor, measuring a measured value of oxidation-reduction potential of the mixed liquor, comparing the measured value of oxidation-reduction potential and the setpoint value of oxidation-reduction potential, generating a control signal based at least in part on the step of comparing, controlling operation of an aeration device using the control signal, acquiring at least one value corresponding to the control signal and adjusting the setpoint value of oxidation-reduction potential using the at least one value. The value includes a frequency of operation of the aeration device.