Milano San Rocco - Municipal Wastewater Treatment Plant
Milano San Rocco municipal wastewater treatment plant handles 40% of wastewater of the city of Milan and a part of the discharge of the municipality of Settimo Milanese (population equivalent of 1,050,000). It is located south of Milan, between the districts of Rozzano and Opera, in a protected agricultural estate. Almost all treated water can be reused for farm irrigation and additionally, its versatile structures can accommodate exceptional storm water loads.
The plant’s strongest point is the simple design of its treatment process. The activated sludge technology adopted is a tested method already tried in many facilities. In this specific application, it is further optimized by a biological treatment stage (step feed and alternating zones processes). The final step in the treatment chain, disinfection by ultraviolet radiation, produces water suitable for agricultural irrigation at a rate of 14,400 m3 /h in the dry season.
The WWTP is of extreme importance for the city of Milan as it improves the environmental quality of surrounding countryside and conserves the local water resources. The plant is indeed fully compliant with the principles of sustainable development.

Resources needed

Construction began in September 2002 and was completed in just 21 months on 7 June 2004, 86 days ahead of the contract schedule.

Evidence of success

Treating the water allows the WWTPs to discharge directly in the river Lambro Meridionale and to dedicate water flows to the water bodies connected to the irrigation network, Roggia Pizzabrasa and Roggia Carlesca, in the peak months, from may to august. The high quality level of the resource does not compromise the agricultural practices and encourage the farmers not to adopt more traditional water sources as drinking water or groundwater.

Potential for learning or transfer

The WWTP contribute to the purification of wastewater showing that a solution for improving urban water management is feasible and can also be at the cutting edge: treated water from the WWTP of Milano San Rocco not only significantly exceeds the requirements of current regulations but is also in line with foreseeable legislative changes.
The wastewater used to irrigate the rural areas is a precious resource for agriculture, also from the circular economy viewpoint. The WWTP is indeed a great example of reduction of water demand from conventional sources and efficient use of water resource, even across sectors.

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Main institution
Lombardia, Italy (Italia)
Start Date
January 2002
End Date


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