Biological recovery of Rare Earth Elements

Using bacteria to clean waste water and recover metal ions.

Introduction

Metals are in finite supply, and so metal scarcity and supply security are global issues. Moving to a sustainable circular economy through the design, engineering and repurposing of waste streams can help address these issues. Synthetic, or engineering, biology, is a technology that has allowed us to design and engineer bacteria to repurpose our waste streams that represents a potential greener alternative to current methods to recover and de-toxify waste. The coming together of industrial applications with those of academic research presents a new way to address a real world problems and trial and evolve the feasibility of novel technological platforms.

Challenge

Scottish micro-company P-BLOCK Ltd is an independent environmental and management consulting firm who focus on de-risking the business activities of their client base by providing solutions to zero waste and process optimisation challenges. The company wanted to test their novel PS-1 productto see if it could recover rare earth metals diluted in a liquid medium derived from a process they operate.

IBioIC funded P-BLOCK Ltd and Louise Horsfall’s team at the University of Edinburgh to examine a locally derived waste stream that was known to contain this valuable and critically limited resource.

Solution

P-Block undertook market research and provided the ‘leachates’ – waste waters which contain metal ions to Louise Horsfall’s group who grew specialised bacteria that can produce nanoparticles from metals contained in waste waters. Nanoparticles are nano-sized particles of metals with unique properties and are highly valuable with a wide range of industrial uses. Analysis found that the metals in the solution were recovered by using microbes, with some of the recovered metals potentially in the form of nanoparticles but detailed analysis found the majority to be silica.

The metal-rich feedstock liquors from PS-1 production were suited to microbial action in general and a very high percentage of metal was able to be recovered from them. However the PS-1 eluents were not well suited for the microbial conversion of the metal ions to nanoparticles.

Though a  specific nano-element was successfully recovered from both the feedstock liquors, the element has limited immediate market potential and also requires focussed optimisation research into recovery processes.

Nanoparticles

Outcome

While bacteria demonstrated the production of silica as nanoparticle, something not previously reported for these bacteria, the more desirable metal nanoparticles were not found though the metals themselves were still recovered. P-Block is now able to focus on additional research into a related chemical recovery process, while the Horsfall group can focus on further adaption of their microbial recovery platform to address some of the issues highlighted in this project.