The MBR Book: Principles and Applications of Membrane

Figure 5.24 The original plant at Brescia
Table 5.13 Discharge design criteria, Brescia plant (from Table 1,
Annex 5 of D.Lgs 152/99)
Parameter Units Regulation limit Design Value
COD mg/L 125 125
BOD mg/L 25 25
TSS mg/L 35 5
TN mg/L – 10
Total P mg/L – 10
Escherichia UFC/100 ml – 10 on 80% of the samples
100 on 100% of the samples
Case studies 237
activated sludge treatment system to an MBR. High effluent quality and limited
available footprint were the key driving forces leading to the decision to employ MBR
technology for the plant upgrade. The need for improved effluent quality resulted
from new Italian legislation (Community Directive 91/271/CEE and D.Lgs. 152/99),
requiring mandatory nitrification/denitrification and effluent TSS limits lowered from
80 mg/L to 35 mg/L (Table 5.13). In addition, ASM had extremely limited available
land to extend the plant footprint. Estimates for conventional processes treating the
same capacity and incoming loads showed that the footprint required would be twice
that of an MBR for the biological reactor and roughly six times greater for the final sedimentation.
The decision to pursue the MBR solution was also made easier by prior
experience with the same membrane technology at full scale from the summer of 1999
onwards for the plant’s leachate treatment system, with positive results. The upgrade
was initiated in 2001 and completed in October 2002. The MBR system was expanded