The aim of this work is to develop an integrated control of anaerobic digesters in wastewater treatment plants, to ensure optimal depollution performances. To achieve this goal, we have to summarise our knowledge in a mathematical model, which is an essential tool for control design.Various control strategies can be chosen, but their performances are very different (stabilisation, biogaz production,F F F). Each of them is evaluated through 3 criteria. Then we present an original linear model for process stability which take into account the input pollution (flow rate, concentration). We show with simulations how this model help us to select the appropriate control strategy and the improvement of depollution efficiency.