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Digestate evaporation for biogas plant

Four-stage vacuum evaporator

At our customer Jakob Bösch AG in Switzerland a digestate evaporation system was integrated into the existing biogas plant. The volume of digested material is reduced by the evaporation and the product ASL, ammonium sulphate solution, is obtained. In addition, the nitrogen concentration in the fertilizer can be lowered due to the nutrient balance of the evaporation and thus the nitrogen/phosphorus ratio per hectare of application area can be optimized.

Facts about the project:

Four-stage vacuum evaporation: The first stage is heated with the thermal energy of the CHP, for the further evaporation stages the vapour condensation of the previous stage is used.
Digestate: 35.000 t/a
Sulphuric acid

Distillate: 19.000 t/a
Concentrate: 14.000 t/a.
Ammonium sulphate solution, ASL: 2.000 t/a. Mineral fertilizer