Up-Whey - Upstream processing of lactose whey for bulk chemicals and energy production

Michael Mandl, Marlene Kienberger, Paul Demmelmayer, Stefan Pflügl, Regina Kutscha, Angelo Gössi, Alan Pérez, Wolfgang Riedl

Research output: Contribution to conferenceAbstractpeer-review


The scope of the UP-Whey project includes the development and assessment of new technologies for valorising dairy wastes, in particular sour and sweet lactose whey for sustainable production of chemicals such as (i) lactic acid (LA) and (ii) isopropanol. The focus of the lactic acid process is not on the fermentation, but on the development of an integrated lactic acid downstream process suitable for complex solutions using a membrane-supported liquid-liquid extraction approach. The fermentation process for producing isopropanol is designed to be robust to directly valorise typical dairy waste side streams to avoid further pre-treatments. Works also include downstream processing to separating isopropanol at high concentration and quality. Developed processes are used to define scenarios for system integration into a whey biorefining. Technology scenarios will be assessed from a technical, economic (prefeasibility) and environmental (LCA) perspective. The assessment also includes the production of biogas (power & heat) from whey as a reference scenario, results of UP-Whey will hence give a clear status on product and energy scenarios for utilising dairy wastes. Presentation provides a status of work and interim results of process developments with a clear focus on lactic acid and isopropanol.
The investigation of a membrane supported liquid-liquid extraction for LA involved a solvent screening, the calculation of mass transfer based on a rigorous model, the evaluation of the main operating conditions (flow rate, membrane area, flow direction and temperature), and the implementation of a subsequent back-extraction step [1&2]. Commercial PTFE capillary membranes were used due to its chemical stability and ease of cleaning [2]. A solvent phase consisting of tri-octyl-amine (TOA, 20 wt.%) and 1-decanol was used as base case and resulted in a high extraction efficiency, green solvents, including deep eutectic solvents boosted the extraction efficiency by a factor of up to 10% [2]. In all cases LA was successfully removed from any feedstock, including a technical fermentation broth, without any crud formation. After back-extraction an aqueous LA-solution with a concentration of 8-10% LA was achieved. The obtained overall mass transfer coefficients were in the range of 1.5 - 2.5·10-7 m/s and thus is in good agreement with typical values of membrane-supported extraction processes [3&4]. Further work will focus on optimizing the operating conditions of LA extraction with the PTFE membrane contactor, based on a sensitivity analysis combining modelling and experimental work. Further work will deal with the transfer of deep eutectic solvents to the membrane reactor and also the pre-treatment of sour whey.
Isopropanol fermentation process development included a screening phase to identify the “best producer” among several Escherichia coli W strains engineered for isopropanol production. After confirming its suitability for whey utilization, we assessed the strain performance in different bioprocess scenarios. Initial screenings in batch mode cultivations revealed the capability for the concomitant uptake of lactose, galactose and lactate contained in sour and sweet whey. Additionally, fed-batch and continuous approaches will be investigated and will allow the identification of key performance parameters. The subsequent determination of the optimal process mode will be done with regard to minimal feed pre-treatment, high productivity and low CO2-yield. To allow for efficient downstream processing and to avoid accumulation of isopropanol up to inhibitory concentrations, possibilities of in situ product removal will need to be implemented. Eventually, the final process will be subject to economic and environmental evaluation.
Results on TEE -technical, economic and environmental assessment of whey biorefinery scenarios are expected to be available by July 2024.

[1] Chemical Engineering Science: X 13 (2022) 100119
[2] Separation and Purification Technology 241 (2020) 116694
[3] The Canadian Journal of Chemical Engineering, Volume 77, October, 1999
[4] Mass Transfer in Multiphase Systems and its Applications, IntechOpen, London. 10.5772/15276.
Original languageEnglish
Publication statusPublished - 31 Jan 2019
Event7. Mitteleuropäische Biomassekonferenz: CEBC 2023 - Messe Graz, Graz, Austria
Duration: 18 Jan 202320 Jan 2023


Conference7. Mitteleuropäische Biomassekonferenz: CEBC 2023
Abbreviated titleCEBC 2023
Internet address

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