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Bresso:enhancement of biomethane upgrade from sewage sludge by algae valorization

Type of organisation or company:

Bresso (MI)

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Project elaborated in partnership: 
Submitted by: 
Davide Scaglione
Start/End date: 

Type of funding:

Gruppo CAP

Contact details


BIOMETHANE: CAP HOLDING, at the Bresso/Niguarda wastewater plant, has installed two sewage sludge biomethane upgrade plants, one based on membrane technology and the other on zeolite filtration.

The ultimate aim of the project is to evaluate the technical feasibility of biomethane production from sewage sludge accordingly to CEN standards. Depending on the evolution of national legislation, the potential end-use of biomethane is: the introduction into the national natural gas network and the use as a fuel for automotive (reference standards: UNI TR 11537 and EN 16723 Specifications for biomethane for injection in the natural gas network) and 2 (Automotive fuel specifications). The first test results were validated by CNR-IIA (National research center - Atmospheric Pollution Institute) and by FCA Automotives with which CAP HOLDING has signed technical collaboration agreements.

The study has shown that the production of biomethane (compliant to all requirements required by the aforementioned standards) by sewage sludge is technically possible using a technology already applied to biogas produced by other biomasses. The industrialization of the plant (1,1 M€ investment) is on-going with the tender already concluded and contract awarded.

The estimated biomethane production at Bresso WWTP will be 341.640 kgCH4/year, enough to supply fuel for 416 cars (20.000 km/year each). The plan is to convert the complete vehicle fleet of the company to methane cars, first 150 cars purchase: IIIQ/2018.

Check BIOMETHANE production details

ALGAE VALORIZATION: The idea is to grow microalgae and put them into the purification process to improve the quality of the wastewater by reducing the content of micro-pollutants. Algae, in fact, are able to grow using the nutrients present in the wastewater, reducing their concentration. At the same time algae need CO2 that can be recovered from the exhaust gases produced by the biomethane upgrade plant in a complete circular path.


Main results: 

The project has been validated by the national research center. The biomethane industrial plant realization is on-going with completion foreseen for the IIIQ/2018.

  •  Biomethane production: 341.640 kgCH4/year;
  • 8.320.000 km of road total, equivalent to over 200 times the circumference of the Earth;
  • CO2 emission reduction: 97% compared to gasoline vehicles;
  • 3.720 KgCO2/km saved (replacing 200 cars);

The microalgae cultivation details and results can be found at the website The first results have been presented during the “ALGAEUROPE Conference” (05-07 December 2017, Berlin-Germany) with an oral presentation titled: “Integration of microalgae culturing as a side-stream process into WWTP”. The microalgae can grow on digestate (areal productivity 4-10 gDW*/m2/d) with high P removal and with photo-oxygenation that supported nitrifiers activity. The algal biomass sent to the digesters could increase by 10% the present biogas/biomethane production of Bresso WWTP.

*dry weight.