An adaptation of a pressure-based most-open-valve control strategy to be applied in aeration control systems of any full scale Wastewater Treatment Plant (WWTP) is described in this paper. This control strategy minimises aeration energy consumption by leading the aeration system to work under the minimum pressure level that is possible given the air distribution system design characteristics and the effluent criteria. Several fuzzy-logicbased control loops are used in the different levels of a supervisory control architecture where knowledgebased rules are also applied. Results obtained in the implementation of this control strategy in three WWTPs with different configurations showed the capability of fuzzy algorithms to maintain dissolved oxygen concentration and pressure always close to setpoint values. Average electrical energy savings of 25 %, 22 % and 16 %, where achieved, respectively, in each WWTP, quantified as kWh per kg of removed COD.