avoid peak flow discharges of treated wastewater into the
sewerage) is no longer necessary (Vives et al., 2003).
To better assess the convenience of SBBGR treatment, it would
be advisable to compare the results of this study with those
achievable with other technologies, especially in terms of specific
treatment cost. However, due to the high compositional variability
of textile wastewaters, only experiments carried out on the same
wastewater type can guarantee a good evaluation of advantages
and disadvantages of the technologies under comparison, as done
by Papadia et al. (2011), who analysed the performances of four
different biological treatments for a real wastewater. Their study
proved that conventional activated sludge performance is more
sensitive to organic loads if compared to innovative treatments
(like Bioflotation or a fixed bed biomass reactor) because of the
lower biomass concentration. Moreover, even if Bioflotation
showed the highest removal capacity, a decrease in COD removal
was observed with OLR. On the contrary, as demonstrated by the
results previously shown, SBBGR is able to maintain constant good
performances up to 2.4e2.6 kgCOD m3 d1, 5 times higher than the
maximum load (0.5 kgCOD m3 d1) tested by Papadia et al. (2011).
Nevertheless, apart from the high cost, in current treatment
methods involving physical and chemical processes, sludge
disposal problems (accumulation of concentrated sludge) can arise
and excessive use of chemicals can also lead to secondary pollution
(European Commission, 2003). Biological systems able to effectively
degrade textile wastewaters are preferable because they are
cheaper and produce lower amounts of sludge. As sludge treatment
and disposal is a key element in the global cost of a treatment,
SBBGR can be a promising technology for on-site treatment also
due to its very low sludge production