EtAcMem - Production of ethyl acetate from milk residues with Kluyveromyces marxianus and product recovery by membrane process
In 2020, 32.6 million tons of milk will be processed in Germany. A high proportion of the milk is used to make quark and cheese, with large quantities of whey being produced. Milk powder, milk proteins and lactose are produced from the milk. The milk proteins are separated by ultrafiltration, the milk solids are concentrated by reverse osmosis and dehydration, and the lactose is crystallized. The last step produces a mother liquor (melasse), which is difficult to recycle because of its high salt content.
Melasse still contains 150 to 200 g/L of lactose and about 90% of the milk's minerals, but is often considered waste because of its high mineral content. The lactose contained in melasse is an interesting source of raw materials for biotechnological processes, such as the production of ethanol, acetoin, bernstein acid and lactic acid. Up to now, only the production of ethanol has reached the technical scale; since 2008, a plant with an annual capacity of 12 million tons of bioethanol exists in Saxony. L of bioethanol. However, this process has some disadvantages.
Alternatively, lactose can be converted to ethyl acetate using yeast. Ethyl acetate, also known as ethyl acetate, is an organic solvent with a wide range of applications. In 2015, 3.5 million metric tons of the ester were produced exclusively from natural gas. Ethyl acetate is microbiologically easily degradable and is increasingly replacing environmentally harmful solvents, which is why the market for ethyl acetate is growing at an annual rate of 4.5%. The market price of ethyl acetate is strongly influenced by the cost of natural gas and is currently around 2000 €/t. Microbially produced ethyl acetate, on the other hand, would be a sustainable product that, with the right marketing strategy, could be used to produce goods with a good image and high value added.
In the preliminary project (AiF 20311 BR) it was shown that a large part of the organic matter contained in the melasse is converted into ethyl acetate and that the ester formed can be removed from the bioreactor in a process-integrated manner by stripping and largely removed from the exhaust air of the bioreactor by means of a membrane process. Compared to the process for the production of ethanol from melasse, there are a number of advantages: (a) the yeast does not have to be cultivated in a separate process step; (b) the process duration is shortened by a factor of 10; (c) the yeast retains its activity and is recyclable; (d) the stripping of the highly volatile ethyl acetate prevents the product from being blocked; (e) the energy required for the production of the product is lower; (f) the market price of ethyl acetate is higher by a factor of 1.3.
The main research objective of EtAcMem is to create the prerequisites for a short-term implementation of the results into production practice by means of optimization in the laboratory and work on a pilot scale. The optimization of the milk-based production of ethyl acetate on the basis of milk residues at the Institute for Natural Materials Technology (TU Dresden), together with the further development of the membrane-based extraction of the esters at the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS, Hermsdorf), is intended to lead to a technically mature and economically viable process with which dairy companies can make sensible use of milk residues.
Project Funding:
IGF - industrielle Geimschaftsförderung
Förderkennzeichen: 01IF23055N
Project Lead:
© Mann
Private lecturer
NamePD Dr.-Ing. habil. Christian Löser
Head of Bioprocess engineering
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Project staff:
Wissenschaftliche Mitarbeiterin
NameMs Paula Klein Dipl.-Ing.
Bioprozesstechnik
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Project duration:
01.03.2024-31.08.2026