Many of the hi-tech items we use every day like mobile phones, electric cars and renewable energy are reliant on precious metals and rare earth elements (REEs). For instance, lanthanides are used in many electrical items and neodymium is used in powerful magnets which can be found in hard drives, mobile phones and television systems.
Critical minerals such as lithium, silver and tin are used in solar panels and, with the anticipated quadrupling in demand for renewable energy over the next 25 years, our recycling efforts need to improve to cope with this demand.
These REEs and other minerals, like fossil fuels, are a finite resource so there is a real need to take a more sustainable approach to sourcing and recycling them. That’s why scientists at Norwich Research Park are trying to achieve this through harnessing the power of microbiology.
A consortium of universities and research institutes in the UK, including UEA and the Quadram Institute, has been set up to examine this conundrum and establish an open knowledge hub focused on the bio-extraction and bio-recovery of metals.
The Engineering Biology Mission Hub for Environmental Processing and Recovery of Metals (ELEMENTAL) will address the growing need for critical minerals and metals in clean energy technologies. Researchers at Norwich Research Park working on this project include Prof Julea Butt and Prof Nick De Brun at the UEA and Dr Heather Felgate and Prof Mark Webber of the Quadram Institute.
Western governments’ supply chains for tech are heavily reliant on China for processing REEs, which makes them vulnerable to any disruption or change. China has lots of mineral deposits – maybe 40% of the world’s total – and there are also environmental challenges linked with mineral extraction through mining.
In recent years, the Beijing government has imposed export limitations on some of these important elements, creating uncertainty for Western governments. That has emphasised the need to become more self-sufficient and to diversify supply chains.
ELEMENTAL provides a circular economy perspective to this challenge – taking what we already have of these finite resources and using them over and over again rather than dumping them into landfill or draining them into waterways.
Demand for these resources continues to grow due to advancing technologies and AI, so it’s become critical that we do not waste what we already have. A long term strategy is needed where we use biology and natural resources for a greener and cleaner solution.
ELEMENTAL aims to enhance ongoing projects related to mineral extraction, urban mining, industrial waste and nuclear waste using engineering biology tools and approaches. One such focus is bioleaching where microbes help to recover metals from various sources. For example, contaminated soils – such as on brownfield sites – and exhausted mining fields may be rich in valuable metals.
Although mining companies see no value in the sites once they have finished mining, it may be possible to employ novel technologies to concentrate, recover and reclaim important resources from the land. So rather than going back to the source and mining for new metals, the objective is to create a more circular economy where the minerals we already have are recycled and put back into the system.
More specifically, the work at Norwich Research Park is looking at how to engineer microbial proteins or entire micro-organisms to make them more efficient at metal recovery or to give them new and useful properties.
Prof Butt focuses on particular types of bacteria that can move electrons outside the cell which can then be used to recover and concentrate valuable metals and elements.
Prof Le Brun’s team is looking at designing ‘nano cages’ to capture the extracted metals and REEs. One of the challenges of working with these elements is that they are chemically quite similar, so often very difficult to separate one from another. It is also hard to purify them so that they can be used for high grade applications in industrial processes.
As a microbiologist in this project, Dr Felgate’s main aim is to investigate bacteria that utilise metals naturally and control the microbial systems to our advantage. Heather creates large mutant libraries and exposes them to a range of stresses and metal exposure experiments. This helps her to look for certain sections of DNA within the bacterial genome that are important for metal accumulation and survival under extreme conditions.
For example, Dr Felgate has been working with Manchester University on uranium stress responses in bacteria with the aim to clean up radionucleotides fields. She has also been working with other institutes on E. coli experiments for recovering metals such as magnesium, manganese, copper and cobalt.
A specific technology used for this work is TraDIS-Xpress – a rapid and high throughput approach to identify bacterial genes involved in response to a stress. The fitness of massive pools of random transposon mutants are compared between stress and control conditions to identify genes under selective pressure.
The Quadram Institute has pioneered the inclusion of outward facing promoters making it possible to measure the impacts of both gene inactivation and altered expression in a single experiment. The approach can be applied to a wide range of bacteria and used to understand how they are able to survive and grow in any condition of interest.
Dr Felgate’s role includes a good bit of a detective-work. She said, “We are often hunting out specific bacteria mutants from a very large pool! A computer may not always see all of the nuances that could occur so the human eye and interpretation can often make sense of something that a computer overlooks.
We hope that using biology and natural processes will give us greener solutions than if you adopted a purely chemical approach for recycling metals. For example, trying to optimise our experiments so that we can recycle metals in water-based solutions rather than toxic organic solvents, and using ambient temperatures and pressures so that the overall energy requirements are lower.
We also mustn’t forget the human cost of sourcing rare earth elements and precious metals. These minerals are often mined in countries which have insufficient health and safety standards and procedures that have led to death and serious injuries to workers. We have an ethical responsibility to try and mitigate this by reusing what we have already. It makes the work we do as part of the ELEMENTAL project all that more important.”