This paper deals with the design of an integrated co-operative supervision system to optimise activated sludge wastewater treatment. For this purpose a biological wastewater treatment pilot, suitable for industrial up scaling and composed of a biological reactor, a settler, sludge recirculation and aeration systems, has been carried out. The reactor configuration is adjustable to treat both urban and industrial wastewater. The pilot scale allows to reproduce industrial hydrodynamics and RTD (Residence Time Distribution) measurements are presented. The supervisory system includes instrumentation and industrial supervisor. The integrated co-operative supervision approach emphases the importance of process behavior anticipation. Information for the human operator will be extracted from a suitable model and a state estimator, which results are presented.