2. Bacterial stacks: principle, origin and applications

2.1 Operating principle

Bacterial cells are electrochemical systems made up of two electrodes, two conductive materials, connected externally by an electrical circuit. The first electrode is an anode installed in an anaerobic compartment at the bottom of the wastewater, where oxygen is scarce and anaerobic bacteria thrive naturally. These bacteria spontaneously adhere to the surface of this anode to form a biofilm, a complex and robust bacterial structure. Biofilm bacteria feed on the organic matter present in wastewater, oxidizing it. This oxidation reaction transforms the waste into carbon dioxide, which is released into the earth's atmosphere.

Among the bacteria present in the biofilm, electroactive bacteria are able to use the anode as the final electron...