Evaluating the greenhouse gas emissions of a sewage system, which tools and which experiences?

While sewage services are not the most polluting local public services in terms of greenhouse gases, their impact on climatic change will become more and more taken into consideration. More generally, this entry in the accounts will concern the overall environment compartments and not only the water and soils. This criterion will become a decision help element for the choice of new water and sludge treatment processes. The use of existing methods (life cycle analysis approach, carbon status) will probably be generalized to all collective sewage systems whatever their size. However, this supposes that the methodologies to be implemented will be accepted by everyone, which is not the case today, and that a more precise knowledge of the different factors at the origin of greenhouse gas emissions from sewage systems will be available. (J.S.)