2. Biological techniques for intensive ERU treatment: the basics

2.1 Principle

The aim of biological purification is to eliminate biodegradable pollutants present in ERU, whether or not they have been previously decanted. This transformation results in the creation of suspended matter containing micro-organisms and their residues, which can be more easily recovered.

The degradation of pollutant matter can take place by two routes: the aerobic route, in the presence of oxygen, or the anaerobic route, in the absence of oxygen. In the latter approach, which takes place without contact with air, organic carbon is transformed, after decomposition, into carbon dioxide (CO ₂ ), methane and biomass. This specific treatment, known as "anaerobic digestion", is mainly intended for industrial...