Industries often discharge their effluents directly into the environment, impacting rivers and groundwater. They often contain a wide range of pollutants, including heavy metals, oils and fats, acids, etc. It is obviously important to limit or prevent all possible contamination of industrial water on groundwater and rivers and on the environment in general. To do this, it is imperative to control their treatment processes and treat their effluents efficiently. In this context, we have studied a new approach which consists of modelling the treatment plants and subsequently we have optimised the overall performance of the liquid effluent treatment plant. Thus the reduction of the invested costs and the compliance of the liquid effluent treatment plants with the regulations in force.