In the reaction
phase, the filled wastewater was continuously aerated
(with the exception of the first hour for denitrification) by air
injection through porous stones placed close to the upper
sieve and recycled through the biomass supporting material
using a recycle pump, in order to obtain a homogeneous distribution
of substrate and oxygen. Finally, the treated wastewater was discharged by gravity using a port located in
the liquid phase over the bed through the opening of a
motorized valve (duration of the drawing phase: 15 min).