The Pero treatment plant is in operation since 1999 and is located in the South of the City area. The plant is a biological activated sludge with extended oxidation. It is used as the treatment of municipal wastewater from the municipalities of Arese, Baranzate, Bollate, Cesate, Garbagnate Milanese, Lainate, Nerviano, Novate Milanese, Parabiago. (Villastanza), Pero, Pogliano Milanese, Pregnana Milanese, Rho Senago, Solaro, Vanzago, as well as those that are part of the relevant area of Varedo purifier (Ceriano Laghetto, Cogliate, Lazzate, Limbiate, Misinto – Province of Monza Brianza).
Plant flow into the sewage from two consortia collectors inter-municipal network that direction roughly north-south trace in the median direction the basins of Lura and Guise streams. At the Municipality of Bollate also engages the new inter-municipal collector which collects the waste of Varedo purifier.

The treatment cycle consists of:


it consists of the following steps, covered and equipped with suction and air treatment: Screening coarse; Fine screening; Grit removal, de-oiling,-vent; primary sedimentation; intermediate lifting sewage to the biological treatment section; biological treatment, along 8 lines. Each line consists of four phases:

  • sector anoxic pre-denitrification;
  • compartment ventilated nitrification;
  • segment of post-anoxic denitrification;
  • compartment re-ventilation.

Secondary sedimentation; Final lift to tertiary treatment; Chemical removal of phosphorus; Final filtration; Final disinfection carried out with sodium hypochlorite.


it consists of the following steps, covered and equipped with suction and air treatment:

  • Pre-static thickening of primary sludge;
  • Dynamic pre-thickening;
  • Anaerobic digestion;
  • Post-thickening;
  • Treatment of tertiary sludge (powered by water backwash of the final filters);
  • Conditioning and dewatering by centrifuges and polyelectrolyte.


the biogas produced is accumulated in a gasometer, and is used in a combined power generation plant of electric and thermal energy; any excess is flared.


Realization Plant Treatment




Detailed Design and Construction