The operation of the reactor was based on treatment cycles,
each consisting of three consecutive phases (namely
filling, reaction and drawing). During the filling phase (few
minutes), a fixed volume of wastewater was added from the
bottom of the reactor to the liquid volume retained from the
previous treatment cycle using a peristaltic pump.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