Topic Area: 12a. Biotechnology for Sustainable Mining

Formatted Title:

Valorization of Acid Mine Drainage Impacted Waters through Protein-Enabled Rare Earth Element (REE) Extraction

Background/Objectives:

Acid mine drainage (AMD) impacted water containing high levels of toxic metals continues to pose considerable ecological effects to surrounding ecosystems. Historically, AMD generated through mining operations was often discharged directly to the environment. While some sites have installed treatment systems that include lime to increase the pH, at other sites it has been stored on site in open air holding ponds and lagoons, or left untreated, leaving significant volumes of untreated waste to leach into water supplies and bioaccumulate in nearby organisms. An estimated 20,000 to 50,000 mines in the U.S. are affected by AMD and generate hundreds of metric tons of REE each year. Recently, high-affinity REE binding bio-molecules, including lanmodulin (LanM), have been discovered and applied to separate and concentrate REE from AMD-impacted waste streams. However, a major challenge to the commercialization of this technology has stemmed from the identification of a stable and cost-effective deployment system, which is essential to successfully utilize metal-binding proteins and peptides for REE capture. Allonnia’s current system relies on proteins or peptides that are covalently tethered onto surface-activated beads. Allonnia has demonstrated that LanM attached to beads can be used to isolate and purify total REE (tREE) from complex solutions, such as concentrated leachate obtained from media used to treat AMD, and is working to maintain a target cost in line with conventional water treatment.

Approach/Activities:

Allonnia’s strategy capitalizes on the biologically vital and highly specialized cellular processes that govern the acquisition, transport, sequestration, and elimination of metals. This consists of developing deployment systems that will allow these novel biological solutions to create environmentally responsible technologies at scale for operating mining and manufacturing sites. Allonnia’s unique technology utilizes metal-binding proteins attached to an abiotic solid support to selectively complex with REEs in the presence of high levels of competing metals found in AMD and other wastewaters, including aluminum, calcium, magnesium and iron. The ion exchange-like deployment allows for passive wastewater treatment by retaining REEs in the column as non-target elements pass through. The REEs are then eluted at significantly higher concentrations with minimal other cations resulting in a relatively high purity tREE solution. This study focuses on testing the efficiency of REE binding recovery and column re-use to demonstrate recovery of tREE from the feedstock at levels similar to conventional technology.

Evan Costa

Affiliation

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Valorization of Acid Mine Drainage Impacted Waters through Protein-Enabled Rare Earth Element (REE) Extraction