Laterite ore deposits in Brazil and other tropical countries contain approximately 70 % of the world’s Ni and Co resources. High energy and/or reagent costs, accompanied by expensive equipment costs, are generally incurred when recovering Ni and Co via pyrometallurgy or high pressure acid leaching. Several acidophilic bacteria are able to use elemental sulfur as electron donor and couple the oxidation of sulfur to the reduction of molecular oxygen and/or ferric iron, and are thereby generating sulfuric acid and dissolving distinct Ni- and Co-bearing mineral phases partly via chemical reduction, e.g. Mn-oxides. Reductive bioleaching of laterites with acidophiles has been described for anaerobic as well as aerobic conditions. Stirred-tank bioreactor and percolation column laboratory experiments were carried out in the BioProLat project to test various samples from three different laterite deposits in Brazil and to optimize parameters including pH, temperature, aeration, and finding the most suitable bacterial consortium for the bioleaching of Ni and Co. Stirred-tank laterite bioleaching experiments starting at pH 1.5 under aerobic conditions with a consortium of different Acidithiobacillus thiooxidans strains resulted after 15 days in maximal extraction of 83 % Co and 83 % Ni, for 10 % (w/v) pulp density of a laterite sample. Column bioleaching with another laterite sample achieved 95 % Co and 66 % Ni extraction after one month. Eventually, the optimized process will be upscaled, transforming unexploited laterite ores and limonite stockpiles into valuable resources.

Constant depletion of high-grade metal deposits focuses mankind’s attention on technology assuring efficient metal recovery from low-grade deposits. Biohydrometallurgy appears as effective, cost-friendly and environmentally benign technique for resource extraction from metal-bearing phases through microbial activity. Due to number of factors influencing final metal recovery, such as pH-Eh conditions, applied microorganisms, chemical and phase composition of bioleached ore, each deposit should be considered as individual case, and thus examined meticulously.

In this research heterotrophic bacterial strain Pseudomonas fluorescens was investigated in terms of metal bioleaching from polymetallic, organic-rich Kupferschiefer shale. Scrutiny involved two different Kupferschiefer samples, displaying various metal concentrations. Activity of Pseudomonas fluorescens was compared to the activity of Acidithiobacillus thiooxidans strain.

The 35-days-long bacterial incubations proved the effectiveness of Pseudomonas fluorescens towards metals leaching, especially in case of copper and molybdenum. In most cases Pseudomonas fluorescens resulted in more advanced metal solubilization within the solution compared to Acidithiobacillus thiooxidans. Differences between activity of those two strains involve not only metal leaching, but alterations of the shale surface as well.

Additionally, restricting organic nutrient for Pseudomonas fluorescens as potential way of optimizing was examined. Despite lower effectiveness in metal leaching as compared to well-feeded strain, noticeable metal solubilization was maintained. This could reflect either nutrient stress or possibility of obtaining organic carbon from kerogen particles present in both shale samples.

Conducted experiments highlight the role of Pseudomonas fluorescens in metal mobility from metalliferous shale and open the perspective of more detailed investigation of bacterial-mineral interactions and enhancing metal recoveries.

Acidophilic leaching microorganisms are of industrial interest to extract metals from ores. The effect of characteristics such as rugosity, charge, and composition on the colonization of bioleaching bacteria is not yet fully understood. Since cell colonization on pyrite (FeS₂) surfaces is highly heterogeneous, robust massive image analysis methods must be employed.

We investigated the effects of rational modifications of pyrite surfaces on early colonization and biofilm formation ability of bioleaching bacteria. We used confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), Raman spectroscopy, and field emission scanning electron microscopy (FE-SEM) with energy-dispersive spectroscopy (EDS) to characterize the surface of pyrite coupons polished to varying degrees. We further colonized the polished pyrite with three bioleaching strains: Leptospirillum ferriphilum, Acidiferrobacter SP3, and Acidithiobacillus ferrooxidans R1. After 24 h of colonization, samples were imaged using EFM, and massive sets of 176-384 images per replicate were analyzed and semi-quantified using custom-made Python scripts and open-source libraries to obtain the colonization density, area, and shape of cell colonies. The data suggest a slight increase in colonization area in medium polished samples in comparison to low polished ones, but a decrease on highly polished samples. However, Kruskal-Wallis test with multiple comparisons indicated no significant differences in other cell colonization parameters among the different samples.

Critical metals like gallium (Ga) and germanium (Ge) hold strategic importance in the development of modern technologies like optoelectronic devices, semiconductors, light-emitting diodes, and many more. The supply of these metals is not assured due to many reasons. Therefore, new sources and efficient recovery techniques needs to be identified. Thus, attention should be drawn to sources with very low concentrations of these metals which are usually neglected. This is due to high concentrations of contaminant metals and very low concentrations of critical metals. Thus, a highly specific, selective and sustainable process is needed. Siderophore assisted technology “GaLIophore” could be a solution. In GaLIophore, siderophore Desferroxamine B (DFOB) is used to selectively adsorb the metals Ga and Ge from industrial wastewater. DFOB is a highly selective molecule and forms a highly stable complex with Ga and Ge. Interaction of Ga and Ge with DFOB are quite unique and different from one other. Complexation of DFOB with Ge is preferred in acidic pH and presence of chloride ion. While Ga complexes with DFOB across the pH 3-9 and is also not affected by the presence of any anion. Furthermore, DFOB can be re-generated by the addition of excess of ethylenediaminetetraacetic acid (EDTA) at pH 3.5. This leads to the recovery of more than 90% of both the metals at the end and makes the process sustainable. Thus, this technology for the first time demonstrated a solution to recover these critical metals from low concentrated systems in a sustainable and eco-friendly manner.

Ion flotation process offers a sustainable way to separate and recycle critical metals from industrial wastewaters that often have low concentrations of target metals. There is a high demand for new flotation reagents which are preferentially environmentally friendly. Microbial biomolecules are an attractive alternative and we are exploring various biomolecules in this regards. The use of these biomolecules as flotation reagents in the ion flotation process can be termed as ‘bioionflotation’. This biotechnological approach for metal recovery from low concentrated waters is still dawning and more research is required to improve the selectivity and process efficiency. In this work, marinobactin (a suite of amphiphilic siderophores) was investigated as a flotation reagent for the separation of Gallium (Ga) from synthetic solutions. Amphiphilic nature of these siderophores and metal complexation ability make them an interesting molecule for an application in the flotation process. Single metal flotation test suggested the Ga recovery and marinobactin-Ga complexation in the collected concentrates was confirmed by HPLC. Further, effects of various operating parameters on the metal recovery and selectivity were studied. The flotation results of the mixed metal solutions (containing Ga and As at 1 mM concentration), showed 88% of Ga recovery and 11% of As recovery, at 0.25 mM marinobactin concentration at pH 4 and air flow rate of 20 ml/min. These results provide the basis to fully embrace the potential of novel bio-ion collectors in developing a highly synergistic process of bioionflotation for recovery of critical metals from low concentrated wastewater.

The surge in battery demand for both mobility and stationary applications necessitates a critical examination of the environmental impacts associated with battery material production and disposal. Key components such as cathodes, anodes, separators, and electrolytes contribute to environmental degradation throughout their supply chain, emphasizing the urgency for sustainable solutions. Circular economy principles offer a strategic framework for mitigating these impacts by promoting extended product lifecycles and increased utilization of recycled materials. This paradigm shift aims to minimize resource extraction and waste generation, thereby reducing greenhouse gas emissions, toxic exposure, and resource depletion. While challenges persist in achieving perfect circularity due to technical and logistical complexities, embracing the circular economy presents a promising avenue for enhancing sustainability in battery manufacturing and usage. The optimization of hydromechanical Li-ion battery recycling systems involves a multifaceted process encompassing material flow analysis and various mechanical, physical, and metallurgical processing units. The Simulation models utilizing advanced software aid in understanding material composition and flow dynamics, crucial for applying Design for Recycling Principles. Exergy calculation within a thermoeconomic framework further evaluate resource efficiency of the recycling route, and analytical techniques such as ICP-OES and XRD analysis play pivotal roles in identifying complex constituents and guiding process optimization. Regenerated lithium salt assumes integral significance in NMC battery production. This paper underscores the importance of efficient material recovery and recycling in sustainable battery production, emphasizing its critical role in meeting the demands of a greener future.