Dr Fatemeh Pourhossein Alamdari

Sustainable Rare Earth Element Recovery from Secondary Resources: Integrating Bioleaching, Metabolic Engineering and Life Cycle Assessment

Secondary Supervisor(s): Professor Sebastien Farnaud

University of Registration: Coventry University

BBSRC Research Themes:

• Renewable Resources and Clean Growth (Industrial Biotechnology)
• Understanding the Rules of Life (Microbiology, Systems Biology)

Project Outline

Rare earth elements are essential for renewable energy, electric vehicles and electronics, but their supply is concentrated in a small number of countries while conventional extraction can have substantial environmental impacts. Recovering these materials from electronic waste could reduce dependence on primary mining and support a circular economy.

Bioleaching uses microorganisms to release metals from solid materials through biologically produced chemicals. It can reduce energy and chemical requirements, but its application to rare earth elements remains underdeveloped. Industrial yeasts such as Yarrowia lipolytica and Saccharomyces cerevisiae are promising because they can produce organic acids that dissolve metals and may tolerate metal-rich conditions.

This project will develop an engineered yeast-based process for recovering rare earth elements from electronic waste. It will test whether increasing production of selected organic acids, alongside improved metal tolerance and process optimisation, can enhance recovery while reducing environmental impacts.

The research will screen yeast strains and fermentation conditions, using renewable substrates, to maximise organic acid production. Metabolic engineering and multi-omics analysis will identify and modify pathways controlling acid production, by-product formation and metal tolerance. Engineered strains will then be evaluated for direct and indirect bioleaching, with operating conditions optimised to improve recovery and selectivity. Downstream separation will also be investigated. Finally, life cycle assessment and techno-economic analysis will compare the environmental and economic performance of the developed process with conventional approaches.

The project will provide insight into yeast metabolism for metal recovery and establish a platform for sustainable rare earth recovery. The findings could support circular use of critical raw materials and UK ambitions for resource security and net zero.

CASE: Bioleaching Superalloy Waste: A New Circular Route to Critical Mineral Recovery A sustainable process for Tantalum recovery from superalloy waste processes

University of Registration: Coventry University

Non-academic partner: Advanced Alloy Services

Secondary Supervisor(s): Stephen Hall (Advanced Alloy Services), Professor Sebastien Farnaud, Dr Ebrahim Azimi (Advanced Alloy Services)

Project Outline

Tantalum (Ta) is a strategically important critical raw material used in aerospace superalloys, electronics and advanced technologies. Its limited supply, geopolitical vulnerability and the environmental impacts of primary extraction create an urgent need for sustainable recovery from secondary resources. Superalloy-processing wastes represent a potentially valuable source of tantalum, but its exceptional chemical resistance makes recovery particularly challenging.

This interdisciplinary PhD, delivered through a collaboration between Coventry University and Advanced Alloys Services, will investigate the biological mechanisms underpinning microbial mobilisation and selective removal of metals from tantalum-containing superalloy wastes. The project will exploit microbial metabolism to develop new bioleaching strategies based on two complementary approaches. First, microorganisms will be screened for their ability to generate metabolites capable of mobilising tantalum, including organic acids, chelating compounds and other biogenic lixiviants. Second, an innovative inverse bioleaching approach will exploit microbial activity to selectively solubilise contaminating metals, particularly calcium and tungsten, thereby enriching tantalum within the residual solid fraction.

The project will investigate how microbial species, metabolism and adaptation to metal-rich environments influence metal solubilisation and selectivity. Microbial growth, metabolite production and physiological responses to superalloy-derived metals will be correlated with changes in metal speciation and mobilisation. Process parameters including microbial community, nutrient availability, pH, temperature and solid loading will subsequently be optimised to maximise selective metal removal and tantalum enrichment.

The research will therefore generate fundamental understanding of microbe–metal interactions in complex, extreme metal-rich environments, while translating this knowledge into a novel biotechnology for critical-material recovery. Combining Coventry University's expertise in bioleaching and environmental biotechnology with Advanced Alloys Services' expertise in superalloys and metal recycling will provide a unique research environment bridging fundamental bioscience and industrial application. Ultimately, the project aims to demonstrate how microbial processes can transform difficult-to-recycle industrial wastes into valuable secondary resources, contributing to a more sustainable and resilient circular bioeconomy.