Odourous emissions from anaerobic digestion

When it comes to recycling organic waste, anaerobic digestion offers a number of advantages. Among other things, it minimizes waste and produces energy with a low carbon footprint. This process uses anaerobic bacteria and can accept a wide variety of inputs from different origins, leading to the production of biogas, the interesting part of which is methane, and digestate, which can be used as a soil improver by returning it to the soil. Materials are introduced into a digester, where bacteria produce a gaseous fraction and a liquid/solid fraction. However, the molecular families encountered in volatile emissions, both from inputs and products, may have potential impacts on the environment of anaerobic digestion plants. The aim of this article is to estimate the odorous emissions of such plants, in relation to gaseous emissions. In this way, it will be possible to assess the effects of the nature of the inputs, depending on the type of plant, by establishing, whenever possible, the link between chemical nature and odor power. Social acceptability of anaerobic digestion is a major obstacle to the rapid development of this energy production technique, and the particular problem of odours is an important part of the rejection reaction.

Operations of various types have therefore been examined both on the basis of standardized or innovative olfactometric analyses and on the basis of detailed chemical analyses providing information on the qualitative and quantitative aspects of the molecules emitted. At the end of this article, (future) plant operators, engineering consultants or government officials will be able to identify the problem areas for each type of plant, so as to avoid creating odor nuisances in the vicinity.