Treatment performance
The influent to the biological compartment of the Alto Seveso
WWTP, after preliminary treatments to remove grit, sand and
coarse material, was used in our tests. The experimental
SBBGR campaign lasted 200 days. During the first 3 months of
the experimentation particular attention was paid to the
generation of the particular biomass of SBBGR (i.e., a mixture
of biofilm and granules packed in the filling material) by
operating with a high value of hydraulic retention time (HRT),
i.e. 25e30 h, and 8 h-treatment cycles. Thanks to the design of
the reactor, granulation is simply achieved using such a slow
increasing step-feed approach: more details about the startup
of an SBBGR can be found in De Sanctis et al. (2010