Microbial Bioleaching to Enhance Recovery of Precious, Rare Earth and Critical Metals from Municipal Solid Waste

Interdisciplinary Areas: Power, Energy, and the Environment

Project Description

The overarching project vision is to redirect how municipal solid waste (MSW) landfills are valued, and to manage them as repositories of highly valued resources. Landfills may contain considerable amounts of rare earth, critical and precious metals, in part due to the disposal of a myriad of electronic devices. Approximately 6.9 Mt of electronic waste was produced in the US in 2019 (1). Such a large waste stream has untapped potential for resource recovery since it contains numerous precious, rare, and critical metals (~50 elements) that are highly valued in the global marketplace (2,3). Even if only 1% of all waste electronics reside in landfills, this would represent between $0.9 to 31 billion of lost value from metals recovery, annually. Recent executive orders further emphasize the critical need to secure such resources domestically (4). Thus, identifying alternative sources for these strategic materials and developing technologies to cost-effectively harvest them is needed to achieve greater energy and economic security. Microbial processes may dramatically increase metal recovery; up to 95% metal leaching efficiencies have been reached when various pure microbial cultures were added to electronic waste, even over short (72 hour) timescales (5).

The overall goal of this project is to develop a microbial bioleaching process to capture precious, rare, and critical metals from landfills. Research objectives include: (1) characterizing metals of interest in existing landfill leachate samples to determine the scale and appropriate geographical application of this technology, (2) identifying microbes within the landfill leachate samples and elsewhere that carry unique traits to maximize metal solids leaching, (3) adding individual microbial isolates and consortia to bench-scale bioreactors containing electronic waste to monitor leaching potential, and (4) conducting a comprehensive cost-benefit analysis to assess the process’s economic feasibility. Overall, such research initiatives will result in a well-defined microbial bioleaching process that will transform landfills into more sustainable resource recovery entities.

Start Date


Postdoctoral Qualifications

Doctoral degree in environmental engineering, microbiology, or related fields. Additional skills related to analytical chemistry and processing complex matrices to quantify inorganic species (e.g. using ICP-OES and ICP-MS), and strong expertise in molecular biology as related to microbes is highly desirable.


1. Amisha D. Shah, Assistant Professor, Lyles School of Civil Engineering and the Division of Environmental and Ecological Engineering (adshah@purdue.edu)
2. Inez Hua, Professor, Lyles School of Civil Engineering and the Division of Environmental and Ecological Engineering (hua@purdue.edu)
3.Lori Hoagland, Professor, Horticulture and Landscape Architecture (lhoaglan@purdue.edu)


1. Forti, V., Baldé, C.P., Kuehr, R., Bel, G., 2020. The Global E-waste Monitor 2020: Quantities, flows and the circular economy potential. United Nations University (UNU)/United Nations Institute for Training and Research (UNITAR) – co-hosted SCYCLE Programme, International Telecommunication Union (ITU) & International Solid Waste Association (ISWA), Bonn/Geneva/Rotterdam.

2. Buechler, D. T., Zyaykina, N., Spencer, C., Lawson, E., Ploss, N., Hua, I., Comprehensive elemental analysis of consumer electronic devices: Rare earth, precious, and critical elements. Waste Management 103, 67–75 (2020).

3. Gutiérrez-Gutiérrez, Silvia C., Frédéric Coulon, Ying Jiang, and Stuart Wagland. 2015. “Rare Earth Elements and Critical Metal Content of Extracted Landfilled Material and Potential Recovery Opportunities.” Waste Management 42: 128–36. https://doi.org/10.1016/j.wasman.2015.04.024.

4. White House, 2021/02/24, Executive Order on America’s Supply Chains, https://www.whitehouse.gov/briefing-room/presidential-actions/2021/02/24/executive-order-on-americas-supply-chains/

5. Srichandran, H., Mohaptra, R.K., Parhi, P.K., Mishra, S., Bioleaching approach for extraction of metal values from secondary solid wastes: A critical review, Hydrometallurgy, 189, 2019, pp. 105-122.