Thin liquor
The thin stillage is in the ethanol - distillation accumulating Abspaltprodukt obtained by separating the liquid from the solid components of the distillation residue (the slop ) is obtained.
When burning alcohol or the production of bioethanol from distillable raw materials such as molasses and other starch or sugar-containing raw materials , depending on the raw material, between 1,100 and 1,400 l of raw stillage with a dry matter content of 7-10% are produced for every 100 l of pure alcohol . The solids can now be separated by decanting , sieving or centrifuging and thus condensed into so-called thick stillage (dried dry stillage or Dried Distillers Grains with Solubles , DDGS), so that the liquid thin stillage remains as a fine suspension.
Thin stillage is used as feed and fertilizer as well as a fermentation substrate for biogas production. The industrial biotechnology can use the material as a nutrient medium. In modern distillation processes, stillage can be returned to the distillation process (recycling).
use
Feed and fertilizer
The German law on the spirits monopoly stipulated for a long time that grain or potato pulp produced in agricultural distilleries must be completely fed to one's own cattle. However, the compulsory feeding has been lifted in recent years, so that stillage can also be applied to agricultural areas as a fertilizer. In solution or suspension, in solution or suspension, in addition to unreacted starch and sugar residues, rich amounts of fats, proteins, salts as well as vitamin B created by yeast fermentation are found, so that they are well suited as supplementary feed . Ideally, it is fed warm, as it is then more digestible and is still sterile due to the preceding distillation process. If it cools down, it is very susceptible to acidification and putrefaction and should therefore be used no later than the day after it is burned.
Commercial distilleries and industrial ethanol refineries usually do not have enough livestock or land to use the stillage immediately as animal feed or fertilizer. Here the thin stillage is mostly evaporated into a vinasse- like syrup with a dry matter content of 23–45%, which is traded as Condensed Distillers Solubles (CDS). This can either be used in its pure form as feed or mixed with the wet thick stillage and then fed. Such a mixture of thick stillage and CDS is traded as WDGS (Wet Distillers' Grains with Solubles) .
Biogas raw material, nutrient substrate
Since the drying and evaporation of stillage is very energy-intensive, it has been increasingly used undried as a substrate for the production of biogas in recent years . This means that up to 50% of the process energy required for distillation can be provided. In the USA in particular, it is mixed with silage and fermented in biogas plants . The residue remaining after the production of biogas fermentation residue can be used as fertilizer can be used. In Germany, this is the case to a lesser extent, as the smaller farm sizes often make an own biogas plant seem unprofitable and the transport of the stillage requires very complex logistics. Thin stillage can serve as a nutrient substrate for biotechnological processes, for example for fungal mycelia, which are left over from biotechnology and synthesize the biopolymer chitosan .
recycling
With advanced distillation technologies such as the Hohenheim dispersing mash process, the thin stillage can be recycled, i.e. it is returned to the mash in order to minimize the supply of fresh water during the distillation process. A higher total ethanol yield can be achieved through such a cycle.
Individual evidence
- ^ Heinrich Kreipe: Grain and potato distillery. Verlag Eugen Ulmer, Stuttgart, 1981. pp. 102-106.
- ↑ Law on the Spirits Monopoly ( Memento of the original of September 24, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (Federal Ministry of Justice).
- ↑ Hans-Joachim Pieper: Fermentation technology alcohol production. In: M. Kling, W. Wöhlbier: Trade feed. Vol. 2 A. Verlag Eugen Ulmer, Stuttgart 1983. pp. 91-106.
- ^ Greg Lardy: Feeding Coproducts of the Ethanol Industry to Beef Cattle (College of Agriculture, Food Systems, and Natural Resources).
- ↑ Agler, Garcia, Lee, Schlicher, Angenent, 2008: Thermophilic Anaerobic Digestion to Increase the Net Energy Balance of Corn Grain Ethanol. Environmental Science and Technology 42: 6723-6729.
- ↑ G. Groeger, W. Geyer, T. Bley, J. Ondruschka, 2006: Fermentative production of chitosan from fungal mycelia. In: Chemie Ingenieur Technik, 78/4, pp. 479–483.
- ↑ D. Pejin, L. Mojovic eta al: The bio-ethanol production with the thin stillage recirculation. (PDF; 367 kB) In: Chemical Industry & Chemical Engineering Quarterly 15: 1, 2009.
