This paper presents a comparative analysis among four control strategies for the control of a combined anaerobic-aerobic wastewater treatment configuration. The anaerobic stage is an Upflow Anaerobic Sludge Blanket (UASB) reactor, whereas the aerobic stage consists of the Activated Sludge (AS) process. The control variables are solids concentration in the effluent and sludge wastage rate. The proposed control strategy is considered the most reliable among them. It is based on two cascaded PI-controllers for the solids concentration in the effluent and a look-up table for the sludge wastage rate control. Experimental and simulated results are presented.