USING NATURE’S POWER TO CLOSE THE REE-CIRCLE

REEs power modern tech, from phones and cars to industrial systems and clean tech, and demand keeps rising. [1] Mining is costly for the planet, and at end-of-life many REEs still go unrecovered; in the EU today, <1% are recycled, which is why policymakers have moved: the EU adopted the Critical Raw Materials Act to jump-start domestic recycling, and the U.S. Department of Energy is actively funding critical-materials recycling and processing. [2–4]

When scouting promising media containing recoverable rare earths, we focused on red mud (bauxite residue), a problem in its own right. This highly alkaline sludge is toxic and typically sits in large reservoirs with no clear downstream plan; the 2010 Ajka spill in Hungary showed the risks starkly. [5–6] However, red mud reservoirs are not unique to Hungary; they exist across the globe, in countries such as Guinea, India, Vietnam, and Australia. Communities in all of these regions face the environmental and health challenges posed by this hazardous waste. [13] Experts we consulted expressed strong interest in new ideas that make cleaning up red mud economically attractive (see Human Practices page).

Today’s REE-recovery bottleneck is simple: concentrations are low, so capture rarely pays, and conventional extraction tends to be chemistry- and energy-intensive at dilute levels. [1,4] We aim to flip that script, enable and incentivize red-mud cleanup, by letting biology do what it does best: work over longer timeframes, thrive at low concentrations, and run on sunlight.

Instead of defaulting to transformed bacteria for bio-mining, we turned to algae, which naturally accumulate metals; microalgae are increasingly studied for REE capture from wastewaters and leachates. [7–8] Our chassis: Chlamydomonas reinhardtii, the model alga. Our goal: equip it to selectively and tightly bind REEs in aqueous media. Nature already offers a blueprint—lanmodulin, a protein with exceptional lanthanide affinity—showing that protein-based capture can be highly selective; this informs our binding strategy. [9–10] To counter eukaryotic silencing, we opted for a CRISPR/Cas9 precise knock-in of our cassette into the nuclear genome of C. reinhardtii, rather than random integration. [11]

Our workflow: (1) pre-treat red mud; (2) an accumulation phase where algae grow in REE-containing media and bind the metals; (3) incinerate the algal biomass to ash and recover REE-enriched ash for conventional downstream extraction, a phytomining-style step used to concentrate metals from biomass. [12]

To demonstrate a practical setting for accumulation, we also built a prototype algal bioreactor. Its design, borrowed from food-production best practices, aims to boost growth, simplify handling, and pave the way for scalable, nature-powered REE recovery. Learn more about our bioreactor design on our Hardware Page.

While advancing our work in algal engineering, we aimed to make the principles of synthetic biology accessible to a broader audience. We dedicated substantial effort to raising public awareness of the challenges, opportunities, and risks associated with synthetic biology, as well as potential strategies to address them. To ensure a well-informed and responsible approach, we actively engaged in dialogue with experts across multiple disciplines, drawing inspiration from their expertise and integrating their feedback. Our project embraced an interdisciplinary perspective, incorporating themes such as waste management, biosafety, protein design, and biomining. Through school visits and workshops, we shared our enthusiasm for synthetic biology and communicated our project’s goals and challenges to the wider public.