Application of Biosorption for REE Separation from Coal Byproducts

Technology Partner: Lawrence Livermore National LaboratoryAward Number: FWP-LLNL-18-FEW0239

Project Duration: 3/1/2018 – 2/28/2021
Total Project Value: $950,000

Key Technology Area: Separation Technologies

The objective of this research is to determine whether biosorption can be used as an inexpensive and cost- effective means for rare earth element (REE) recovery from leachate of pre-combustion and post-combustion coal by-products. This project will develop a biofilm- based continuous flow-through system in an airlift bioreactor. This effort will also improve the biofilm stability of E. coli using a bioengineering approach to incorporate surface binding tags. These surface binding peptides are known to improve adhesion and increase biofilm stability under high shear force. This objective will be carried out in parallel with a Caulobacter biofilm formation activity in a separate, but related project (TCF-17-13365). A single bacterial platform for the

application of airlift bioreactor will be down-selected based on several evaluation criteria, including (1) biofilm density (number of cells per unit area), (2) biofilm forming efficiency (proportion of cells that attach to the surface in a cell population), (3) biofilm stability, (4) REE-binding ligand density (number of REE- binding ligands incorporated per cell), and (5) REE adsorption capacity per unit area of the biofilm. At conclusion, the project is expected to deliver a bench- scale demonstration of an airlift bioreactor for REE recovery and demonstrate its technical feasibility with preliminary economic viability analysis and a plan for commercialization.

Airlift bioreactor design and process flow diagram. The proposed system consists of a two-stage semicontinuous process including (1) a closed mechanically agitated bioreactor (MAB) used to grow the microbes, (2) an open cylindrical container as a packed column for biofilm formation on carrier disks, (3) an airlift bioreactor (ALB) for adsorption of REE onto biofilm carrier disks, and (4) an open-packed elution column (EC) with (5) circulating citrate from a citrate tank for REE desorption and recovery.

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