Circular economy

SUEZ supports Mulhouse region's energy transition by building a methanation unit in Sausheim (France)

On Monday 12 November, Jean Rottner, President of the Mulhouse region’s SIVOM, and Marie-Ange Debon, Senior Executive VP of SUEZ in charge of France, Italy and Central Europe, laid the first stone of a methanation unit that will allow to recover 100% of sludge from Sausheim wastewater treatment plant to supply green energy for the equivalent of 125 urban transport buses by 2020

Working in perfect synergy with the wastewater treatment plant and the neighboring waste-to-energy power plant, this methanation unit will make possible to valorize in green energy all the sewage sludge and will use the fatal heat of the waste-to-energy power plant to maintain the two methanation tanks at constant temperature (37° celcius). Sludge collected from the methanation process will then be centrifuged and its solid residue recovered as energy.

At the end of the 21-month project, in mid-2020, the facility will have an equivalent treatment capacity of 490 000 inhabitants. It will produce 2,000,000 m³ of purified biomethane every year, which will be injected into the GRDF network to supply the equivalent of 125 urban transport buses (19GWh / year).


Phosphorus recovery: a national first

As a limited resource, phosphorus is a real issue in the circular economy. It is an essential element for agriculture in particular.Thanks to its Phosphogreen process, SUEZ integrates the recovery of phosphorus contained in the treatment sludge into the methanation process and then transforms it into struvite. With the implementation of this process, the Mulhouse region’s SIVOM will be therefore the first territory in France to valorize phosphorus on a wastewater treatment plant, with an annual production of 3,500 bags of struvite for local agriculture.

A structuring project for the Mulhouse Agglomeration

This project is part of the energy transition of the Mulhouse agglomeration and reinforces the energy complementarity between the wastewater treatment plant on the one hand and the waste-to-energy power plant on the other hand:

  • Electricity production for the self-consumption of the two sites,
  • Steam production for the Papèteries du Rhin,
  • Supply of the hot water network for the methanizer heating,
  • Supply of the hot water network for district heating in Rixheim,
  • Mid-2020: biogas production for urban transportation.
Jean Rottner, President of the Mulhouse region’s SIVOM: “the realization of this project is a major element in the energy transition policy conducted throughout the agglomeration of Mulhouse. The entire Sausheim site, which includes the waste-to-energy power plant and the wastewater treatment plant, evolves progressively to become a major actor in the circular economy and renewable energy production, by mixing both production of electricity, steam, gas and fertilizer."