Biomachining: Preservation of Acidithiobacillus ferrooxidans and treatment of the liquid residue

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.

Legacy copper/nickel mine tailings potentially harbor novel iron/sulfur cycling microorganisms within highly variable communities

“…The WPS-2 relative abundance increased at multiple depth ranges between 1-2 m. Many of the NR18 vadose zone pore-water samplers were dry in 2021, and core moisture content is likely to influence WPS-2 abundance, as they are known to be common in dry, bare soil environments (Sheremet et al, 2020). Drier tailings could also explain the decrease in A. ferrooxidans , which are not desiccation tolerant (Díaz-Tena et al, 2017). The taxonomic representation of sulfate-reducing bacteria also changes slightly ( Ca.…”

Legacy copper/nickel mine tailings potentially harbor novel iron/sulfur cycling microorganisms within highly variable communities

“…The WPS-2 relative abundance increased at multiple depth ranges between 1 and 2 m. Many of the NR18 vadose zone pore-water samplers were dry in 2021, and core moisture content is likely to influence WPS-2 abundance, as they are known to be common in dry, bare soil environments ( 46 ). Drier tailings could also explain the decrease in A. ferrooxidans , which are not desiccation tolerant ( 95 ). The taxonomic representation of sulfate-reducing bacteria also changes slightly ( Ca .…”

Influence of Phenylmethylsilicone Oil on Anti-Fouling and Drag-Reduction Performance of Silicone Composite Coatings

“…We took Coatings 2020, 10, 1239 5 of 13 pictures to record the experimental results. We used IMAGE PRO PLUS software (version 6.0) to observe the amount of bacteria attached to the surface of the solid medium [24]. The formula of 2216E solid medium can be found in paper [25].…”