Cométha – SIAAP Syctom innovation partnership for the treatment of organic waste and sewage sludge in the greater Paris area

In the greater Paris area, several million humans generate enormous amounts of waste and wastewater. In order to make the best possible use of this waste, the Cométha research partnership was set up. One of the consortia entrusted with the research is a Franco-German consortium with the participation of Fraunhofer IGB. Here a new modular solution is being tested for digesting the organic components to biogas, subsequent gasification of the digestion residues to synthesis gas and biological conversion of the CO2 to methane, as well as recovery of the inorganic nutrient salts phosphate and ammonium. In the three-stage project the developments at laboratory scale will be followed by piloting on site. Finally, a large-scale plant is to be planned and built based on one of the tested concepts.  



In the greater Paris area, around 6 million inhabitants in 84 municipalities produce almost 2.3 million tonnes of municipal waste annually, which is treated by Syctom (l’agence métropolitaine des déchets ménagers) in 12 industrial plants. The wastewater of almost 9 million people in the Ile-de-France region, which includes Paris, is treated by the SIAAP (service public de l’assainissement fracilien). This makes Syctom and SIAAP one of the largest public operators in Europe in their field.

© Fraunhofer IGB
Plant for drying HTC coal with superheated steam.
© Fraunhofer IGB
Liquid phase and phosphorus fertilizer derived therefrom: Magnesium ammonium phosphate (struvite).

Objective: Co-méthanization with the best energy balance

Both public operators have set up an innovation partnership in order to efficiently convert all municipal organic waste in the greater Paris area combined with sewage sludge into biogas or methane – a regenerative energy source. The aim is to maximize the conversion of organic carbon to methane. By-products are to be minimized and nutrients e.g. phosphates recovered. The highest environmental standards are achieved. Following a competitive bidding process four consortia were contracted for scientific analysis and planning of the pilot unit.


Project plan

The Franco-German consortium with participation of Fraunhofer IGB has developed a solution which optimally combines the individual processes. In phase 1, laboratory-scale investigations were carried out and the pilot plant was designed. If contracted for the next stages, the results generated with this pilot plant will deliver a solid base for the planning and construction of a highly efficient large-scale plant.


The role of Fraunhofer IGB

Fraunhofer IGB helps to realize sustainable, future-oriented nutrient management.

Nitrogen and Phosphorous are recovered leading to no additional load for the sewage plant. Furthermore, Fraunhofer IGB evaluated wet fermentation of the organic waste and sewage sludge mixture with exceptionally good results.



This flagship project makes Paris the world leader in organic waste management in terms of CO2 emissions and environmental footprint. At the same time safe and climate-neutral energy production is ensured.

Project information

Project title

SIAAP – Innovation partnership for the treatment of organic waste and sewage sludge in the greater Paris area


Project duration

  • Phase 1:March 2018 – August 2019
  • Phase 2: since March 2020
  • Overall project timeline: March 2018 – September 2026


Project partners

  • DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH, Leipzig, Germany
  • France Biogaz Valorisation, Strasbourg, France
  • Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Stuttgart, Germany
  • GICON – Großmann Ingenieur Consult GmbH, Dresden, Germany
  • Tilia GmbH, Leipzig/Paris, Germany/France (Coordination)


We would like to thank Le Syctom (l’agence métropolitaine des déchets ménagers) and le SIAAP (service public de l’assainissement fracilien) for funding this project.