The WWTP is located in an urban area of Milan (Italy), and it
receives wastewater from the city (1,250,000 Inhabitant Equivalents, corresponding to 432,000 m3/day average inflow (Pizza,
2014), which includes that from many hospitals. The within-plant
treatment scheme (Fig. 1 ) starts with pretreatments (screening,
sand and oil removal). This step is followed by the biological
treatment with activated sludge, including pre-denitrification and
biological oxidation (8 h hydraulic retention time, 30 day sludge
retention time). After secondary settling, the biologically treated
effluent undergoes rapid sand filtration to improve the removal of
suspended solids and phosphorus.