Optimised bio-electrochemical reactor, in particular for degradation of the chemical oxygen demand of an effluent

A bio-electrochemical reactor for treating a liquid effluent, comprising at least one anode compartment and at least one cathode compartment, at least one separator located between the at least one anode compartment and the at least one cathode compartment, characterised in that at least one amongst the anode and cathode compartments is a microbial biofilm compartment including:

• at least one fluid inlet located at one end of the compartment,
• at least one fluid outlet located at an opposite end of the compartment,
• means for circulating the fluid inside the compartment between the at least one inlet and the at least one outlet according to an X direction,
• an electrolyte comprising electroactive microorganisms,
• a biocompatible granular support material,
• a multi-stage current collector located between the at least one fluid inlet and the at least one fluid outlet of said microbial biofilm compartment, said collector comprising at least two stages each defining a chamber serving as a container for the granular support material and letting the fluid pass, said collector conforming to the shape of the microbial biofilm compartment over the height of said collector measured according to the X direction and having a structure provided with a multitude of orifices not letting the particulate material pass,
• and in that,
• the direction X of circulation of the fluid inside said microbial biofilm compartment is not parallel to a direction Z from the anode compartment to the cathode compartment, and,
• inside at least one chamber of the current collector so-called the fluidisation chamber, a height at rest of the granular support material measured according to the X direction in the absence of fluid circulation inside the microbial biofilm compartment, is a height suitable for fluidisation of said granular support material smaller than the total height of the fluidisation chamber.