Biopolymers Produced by Treating Waste Brewer’s Yeast with Active Sludge Bacteria: The Qualitative Analysis and Evaluation of the Potential for 3D Printing

Gregor Drago Zupančič, Anamarija Lončar, Sandra Budžaki and Mario Panjičko
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Gregor Drago Zupančič: CROTEH Ltd., Avenija Dubrovnik 15, 10020 Zagreb, Croatia
Anamarija Lončar: CROTEH Ltd., Avenija Dubrovnik 15, 10020 Zagreb, Croatia
Sandra Budžaki: Faculty of Food Technology Osijek, Josip Juraj Strossmayer University of Osijek, Franje Kuhača 18, 31000 Osijek, Croatia
Mario Panjičko: CROTEH Ltd., Avenija Dubrovnik 15, 10020 Zagreb, Croatia

Sustainability, 2022, vol. 14, issue 15, 1-16

Abstract: Biopolymers are a suitable alternative for the ongoing problem of plastic accumulation, even though commercialization is difficult, which is reflected in the price of the product. However, costs can be reduced if active sludge bacteria and cheap, accessible substrates such as waste brewer’s yeast are used. Waste brewer’s yeast is a rich source of carbon and nitrogen and is widespread as a substrate in various industries. Thus, the cultivation of active sludge bacteria was performed on waste brewers’ yeast to obtain biopolymers that can be used in 3D printing. FT-IR, TG, and DSC analyses of produced polymers were conducted after extraction, as well as biogas and biomethane potential tests. Results of cultivation under various conditions show that biopolymer content is extremely heterogeneous. However, during cultivation in SBR, signals at 1741.3, 1709.6, 1634.3, and 1238 cm −1 were detected. Further analyses are needed, but when said results are compared to those of consulted scientific articles, there is an indication that at least a small amount of PHA is present in biomass produced in SBR. Biopolymers produced in SBR were used as a material for the 3D printing of a cube. Moreover, testing of the physical properties (Young’s modulus) of a 3D-printed cube was performed. After conducting experiments, it can be concluded that said process, although time-consuming, achieved the goal of printing a stable and rigid 3D-printed cube made from biopolymers. Further optimization of said process should focus on more detailed microbial selection as well as biopolymer extraction. In that way, isolation, purification, and identification techniques will be improved, which could achieve higher biopolymer yield and, thus, make biopolymers more accessible in various industries.

Keywords: brewers’ yeast; active sludge bacteria; anaerobic digestion; biogas potential; biopolymer; 3D printing (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
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