The better performance of SBBGR compared to Alto Seveso
WWTP can be ascribed to the particular type of biomass
growing in the first system consisting of a mixture of biofilm
and granules, completely packed in the filling material of the
reactor. This allows a greater retention of the biomass in the
system and then a much higher biomass age (higher than
150 d). The packed biomass acts as a filtering medium to
remove suspended particulate matter (and the associated
COD) from the wastewater whereas the high age of the
biomass allows the hydrolysis of the captured solids to produce
soluble organic compounds which are then removed by
the same biomass