Abstract: 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.

Abstract: A method and apparatus for conditioning a sensor to measure an oxidation reduction potential of an aqueous solution such that the time to obtain a reliable oxidation reduction potential measurement is substantially reduced. Such conditioning is often necessary when the sensor is moved from potentiometric equilibrium (e.g., the sensor is cleaned, the sensor is exposed to air, and the like). The method may comprise generating a current through a measurement electrode and a reference electrode of the sensor for a duration of time. A reliable oxidation reduction potential measurement can be made as the voltage across the measurement electrode and the reference electrode stabilizes after the duration of time. Depending on the aqueous solution, the stabilized value can be constant or variable.

Abstract: Wastewater treatment controls that maintain the ORP of a mixed liquor at a relatively stable value during a wastewater treatment process such as an aerated-anoxic wastewater treatment process. The wastewater treatment control may compare a setpoint value of ORP and a measured value of ORP of the mixed liquor, generate a control signal based at least in part on the comparison, and control a biological nutrient removal control parameter using the control signal. Values corresponding to the control signal may be acquired and utilized to adjust the setpoint value of ORP to maintain stable operating conditions of the wastewater treatment process.