Microbe Encapsulation for Selective Rare-Earth Recovery from Electronic Waste Leachates

Area of Science:

• Biotechnology
• Environmental Science
• Materials Science

Background:

• Rare earth elements (REEs) are critical for green technologies, but current extraction methods are energy-intensive and environmentally harmful.
• Electronic waste is a growing source of REEs, presenting an opportunity for resource recovery.
• Developing sustainable and efficient methods for REE extraction is a global priority.

Purpose of the Study:

• To develop a novel biosorption-based flow-through process for selective REE recovery from electronic wastes.
• To engineer and encapsulate microbial cells for enhanced REE adsorption.
• To evaluate the performance and reusability of the developed biosorbent.

Main Methods:

• Engineered Escherichia coli displaying lanthanide-binding tags were encapsulated in polyethylene glycol diacrylate (PEGDA) hydrogel microbe beads.
• Microbe beads were packed into fixed-bed columns for flow-through experiments.
• Breakthrough experiments were conducted using electronic waste leachate to assess REE extraction efficiency, selectivity, and column stability.

Main Results:

• The microbe beads demonstrated effective neodymium extraction at flow velocities up to 3 m/h and pH 4-6.
• The microbe bead columns maintained 85% of their adsorption capacity after nine cycles of adsorption/desorption.
• Bench-scale tests showed a two-bed volume increase in breakthrough points for REEs over non-REE impurities, achieving 97% REE purity.

Conclusions:

• The developed microbe beads offer a stable and reusable platform for selective REE recovery from electronic waste.
• This biosorption process provides a promising biomass-based alternative for sustainable REE recycling.
• The technology has the potential to significantly improve the environmental footprint of REE extraction.