: “Developing Biotechnologies for Detection and Recovery of Rare Earth Elements”

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Background: Rare earth elements (REE) are critical components of many advanced technologies including magnets in hard drives and components of lasers. Of the 17 rare earth elements, 16 (cerium, dysprosium, erbium, europium, gadolinium, holmium, lanthanum, lutetium, neodymium, praseodymium, samarium, scandium, terbium, thulium, ytterbium and yttrium) are designated critical minerals and are present in different combinations and concentrations depending on the primary (e.g. ores, red mud, geological deposits) and secondary (e-waste, coal ash and landfill leachate) sources of the critical minerals. Of these 16, all except for cerium and lanthanum, are in undersupply. Individual REE are used in different combinations to develop advanced technologies necessitating the isolation of elements from primary and secondary sources and the purification of defined REE mixtures or individual elements. However current approaches are energy and solvent intensive and do not easily separate the different REE from each other. Biotechnology applications such as bioleaching and biosorption are promising approaches for REE recovery but require further research and development to increase selectivity, efficiency, cost effectiveness and scalability. Brief Description of Anticipated Work: Required Work Objectives: This project will develop novel microbes with increased capability to dissolve and capture REE from solid sources such as crushed ore and e-waste. The project will also examine approaches to increase the selectivity and affinity of biomolecules for different REE. Additionally, the project will investigate different technologies/approaches that improve scalability of REE recovery processes (e.g. concentration and monitoring of REEs during processing). The ultimate goal of this effort is to develop methods that accelerate our ability to recover individual or discrete mixtures of REE from domestic primary and secondary sources. Objective 1: Increase the selectivity and affinity of biomolecules for different REE .  Create semi-synthetic platforms for specific lanthanide-binding, with the reliance on modification of proteins and spores using designed chemical structures for chelation moieties. These platforms should improve the concentration of lanthanides by spores and proteins, while providing methods for tuning protein/spore affinity and selectivity. The specificities of both the semi-synthetic and protein-alone chelators should be further modified using computational models to design peptides and proteins with a variety of affinities and specificities for REE. Objective 2: Technologies/approaches that improve scalability of REE recovery processes. Surfaces of fluorescent proteins should be modified to create protein biosensors that can bind lanthanides with high affinity and selectivity, and also allow FRET detection both in vitro and in vivo of lanthanides (samarium, europium, terbium, and dysprosium). Such biosensors will serve as tools for monitoring the efficiencies of processing streams and of the efficacies of different technologies. The successful offeror work with ERDC researchers to examine novel approaches to condense process streams to increase efficiency of downstream processing events. Results from these objectives will be communicated to ERDC regularly in interim reports and transferred to the Public using conference presentations and the peer-reviewed literature. All methods and protocols will accompany the results and meet peer-review scrutiny for any interim reports. A successful application would likely include experience with genetic engineering of spores, molecular evolution and synthetic biology, and successful publication record of these methods. Public Benefit : Development of approaches to harvest critical minerals from domestic sources is essential to establishing secure domestic supply chains for REE. Furthermore, the environmentally friendly biotechnologies developed here will greatly lower adverse environmental and climate effects caused by existing REE mining approaches. Further, understanding how to selectively isolate REE from many sources will greatly increase our ability to isolate other critical minerals. This project will benefit the public by providing new approaches to harvest critical minerals, by educating the public about environmentally friendly approaches for mining/recycling, and by increasing availability of critical materials for development of advanced technology.

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