The wastewater treatment plant for the Ehn basin has an extremely localised particularity, in that it handles waste liquids from sauerkraut production. Rather than being merely a treatment plant, it is first and foremost an environmental platform that transforms waste materials into renewable energy.

Exemplary nature of the technical solutions implemented

This treatment plant offers very high-performing technical solutions:

  • The plant provides a complete series of water-treatment processes culminating in tertiary filtration using Filtrazur which makes it possible to further refine treatment prior to discharging the water into the river Ehn;
  • An innovative thermal dryer transforms sludge into a product that can be used in the agricultural and incineration sector;
  • Odour treatment by installing a top-of-the-range deodorisation system.

Summary of the skills and expertise that can be seen on the site

Waste liquids from sauerkraut production are acidic, very corrosive and rich in organic matter. Treatment used to be a problem but today they undergo a special methanation process. Fermentation of these liquids makes it possible to produce biogas.

The biogases produced during treatment of sauerkraut production waste liquids are mixed together with those produced during treatment of sludge and fats. The resulting biogas feeds boilers and supplies the site’s heating requirements (premises, sludge-drying, keeping digesters at the right temperature, etc.) Superfluous energy is fed into the electrical grid by means of a process of co-generation.

Key figures

Start-up date: October 2011
204,500 inhabitant equivalents
11 villages served, equivalent to 27,000 inhabitants in the Terres de Sainte Odile area.
Effluent from local sauerkraut factories is the equivalent of 140,000 inhabitants.
The area produces 70% of national sauerkraut production.
Maximum capacity of the plant: 38,700 cubic metres per day
5,464 MWh per year of primary biogas produced (equivalent to the energy consumption of 1,542 inhabitants of France)
Cost of the plant: €23,850,000 excluding taxes

Main stakeholder

Suez Environnement

20 rue des métiers 68000 Colmar

Players involved and their roles

SIVOM du Bassin de l'Ehn

Suez Environnement

Degrémont (constructeur) ; Cofinanceurs : Agence de l'Eau Rhin meuse, Conseil Général du Bas-Rhin, Fonds européen / région Alsace