Biomachining: Preservation of Acidithiobacillus ferrooxidans and treatment of the liquid residue |
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Authors: | Estíbaliz Díaz‐Tena Naiara Rojo L. Gurtubay Adrián Rodríguez‐Ezquerro Luis Norberto López de Lacalle Iñigo Oyanguren Francisca Barbero Ana Elías |
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Affiliation: | 1. Department of Chemical and Environmental Engineering, Faculty of Engineering of Bilbao, University of the Basque Country (UPV/EHU), Bilbao, Spain;2. Department of Chemical and Environmental Engineering, University College of Engineering of Vitoria‐Gasteiz, University of the Basque Country (UPV/EHU), Vitoria‐Gasteiz, Spain;3. Department of Mechanical Engineering, Faculty of Engineering of Bilbao, University of the Basque Country (UPV/EHU), Bilbao, Spain;4. Guserbiot S.L. Vitoria‐Gasteiz, Spain |
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Abstract: | Biomachining has become a promising alternative to micromachining metal pieces, as it is considered more environmentally friendly than their physical and chemical machining counterparts. In this research work, two strategies that contribute to the development of this innovative technology and could promote its industrial implementation were investigated: preservation of biomachining microorganisms (Acidithiobacillus ferrooxidans) for their further use, and making valuable use of the liquid residue obtained following the biomachining process. Regarding the preservation method, freeze‐drying, freezing, and drying were tested to preserve biomachining bacteria, and the effect of different cryoprotectants, storage times, and temperatures was studied. Freezing at –80°C in Eppendorf cryovials using betaine as a cryoprotective agent reported the highest bacteria survival rate (40% of cell recovery) among the studied processes. The treatment of the liquid residue in two successive stages led to the precipitation of most of the total dissolved iron and divalent copper (99.9%). The by‐products obtained (iron and copper hydroxide) could be reused in several industrial applications, thereby enhancing the environmentally friendly nature of the biomachining process. |
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Keywords: | Acidithiobacillus ferrooxidans Biomachining Liquid residue treatment Preservation of microorganisms |
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