imposed through daily biomass purge. GSBR1 and GSBR2 worked
in 6-h cycles with a HRT of 12 h and no imposed SRT (deliberate
biomass wastage was limited to the sampling needs). The feed solution
was inserted atthe bottom ofthe bioreactors with a volumetric
exchange ratio of 50%. At the end of the fill phase, FSBR1 and GSBR1
were additionally supplied with AR14 at the top of the bioreactors.
The reaction phase of each SBR cycle included a mixed anaerobic
stage followed by an aerated stage. Mixing was provided by magnetic
stirring during the non-aerated reaction. During the aerobic
reaction, aeration was supplied by air compressors through porous
membrane diffusers. The different cycle phase durations tested in
the flocculent and granular bioreactors are summarized in Table 1.
Pumping, mixing and aeration were automatically controlled via
an interface by a computer with dedicated software