Bioethanol

Production processes

Bioethanol is a natural product and is manufactured by the fermentation of plants containing sugar and starch. In our plants we produce bioethanol from renewable raw materials and from raw alcohol of agricultural origin.
Our plant in Zeitz produces bioethanol from wheat, maize, barley or triticale as well as from sugar syrups.
At this plant the production of bioethanol from starch-containing cereals takes place in five steps:
  1. Milling, i.e. the mechanical crushing of the cereal grains to release the starch components
  2. Heating and addition of water and enzymes for conversion into fermentable sugar
  3. Fermentation of the mash using yeast, whereby the sugar is converted into bioethanol and CO2
  4. Distillation and rectification, i.e. concentration and cleaning the ethanol produced by distillation
  5. Drying (dehydration) of the bioethanol
Bioethanol can also be produced directly from sugar syrups. This dispenses with steps 1 and 2, which serve to prepare the grain for fermentation.
At the next-generation bioethanol plant in Wanze the bioethanol is produced from wheat and sugar syrups. However, the production process is different as it incorporates a different energy concept and produces different food and animal feed products:
  1. The wheat is cleaned and ground in a mill. The bran is separated from the wheat grains and is used to generate primary energy in a biomass plant.
  2. The next processing step separates the gluten from the rest of the grain.
  3. By adding enzymes the starch contained in the wheat is converted into fermentable carbohydrates, which can then be fermented into alcohol. Sugar syrups can be fermented directly.
  4. In the next step, the fermentation process, yeasts convert the carbohydrates into alcohol and CO2. The alcohol-containing mixture that is produced is referred to as "mash".
  5. Distillation separates the alcohol from the other constituents of the mash.
  6. In the rectification process this alcohol is then cleaned again. The dehydration - also referred to as drying - of the alcohol then removes virtually all the water it contains. The result is bioethanol with an extremely high purity of 99.7 vol.-%.
  7. The other constituents, the so-called "stillage", are thickened and processed into Concentrated Distiller's Solubles (CDS).

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