Tag: Urban Mining

E-Waste – III: Biomining

This is the third in a series on e-waste. Post I established the scale of the problem and the concept of urban mining. Post II examined India’s informal recycling sector and the limits of EPR policy. This post looks at the biotechnology frontier.

Rare Earth Elements, or REES, are not, despite their name, particularly rare in the Earth’s crust.1 The challenge is that they are seldom found in concentrated deposits2, and they almost always occur together, sharing such similar chemical properties that separating one from another is technically demanding and chemically intensive.3 That cost is not merely financial. Conventional REE mining generates radioactive waste, strips landscapes, and produces acid drainage that contaminates groundwater for decades.4

Also, China currently supplies nearly 90% of the world’s REE demand5, a concentration of geopolitical risk that rattled supply chains as recently as 20196, and the geopolitical situation has escalated dramatically since: on April 4, 2025, China introduced export restrictions on seven rare earth elements in direct retaliation for U.S. tariffs78. In October 2025, China expanded those controls further, adding five more REEs critical to magnets and defense, including erbium.9 China did pause some of these restrictions temporarily in late 2025 following U.S.-China trade negotiations, but analysts universally treat the pause as tactical, not structural.1011 The leverage remains.

E-waste has become one of the fastest-growing solid waste streams in the world, with approximately 62 million tonnes generated globally in 2022 alone12, of which less than one quarter was documented as recycled13, yet global REE recycling rates remain below 5%14. Meanwhile, global demand for magnetic REEs alone is projected to surge from 59 kilotonnes in 2022 to 176 kilotonnes by 2035, a tripling in just over a decade. The trajectory is not sustainable.15

What are REEs?
Here are the 17 elements, actively sounding like Tolkienian characters:16

  • The 17 Elements: Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm, the only actually rare REE, and named for Prometheus), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu), Scandium (Sc), and Yttrium (Y).
  • Light vs. Heavy REEs: They are classified into Light Rare Earth Elements (LREEs) (atomic numbers 57-63) and Heavy Rare Earth Elements (HREEs) (atomic numbers 64-71), with yttrium grouped with heavies. HREEs are generally rarer and more valuable. HREEs are more valuable: their greater scarcity relative to demand, and the fact that dysprosium and terbium (both the HREEs) are the critical additives that keep NdFeB magnets performing at high temperatures in EV motors, making them essentially irreplaceable in the short term.17

Currently, global REE recycling rates remain below 5%. Yet the secondary sources are remarkably rich. The permanent magnets in hard disk drives contain neodymium, dysprosium, and praseodymium at concentrations of 2,500–15,000 parts per million, while the phosphors in fluorescent lamps carry yttrium, europium, cerium, terbium, and lanthanum at 1,000–20,000 ppm, concentrations up to 17 times higher than in natural ores.1819 

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Biomining
Using biological organisms to aid mining.

The biological mechanisms involved span a sophisticated toolkit:20​

  • Bioleaching: Microorganisms produce organic acids, siderophores, or other metabolites that dissolve metals from solid matrices. The bacterium Gluconobacter oxydans, for instance, produces gluconic and pyruvic acids that leach REEs from nickel-metal hydride battery powder.​
  • Biosorption: Metal ions bind to functional groups on microbial cell walls or to engineered biomolecules, concentrating them from dilute solutions.
  • Bioprecipitation: Microbes convert dissolved metals into insoluble forms that can be physically separated.
  • Bioaccumulation: Some microorganisms, particularly microalgae, internalize REEs through metabolic processes, serving as biological concentrators.​
  • Bioweathering and Bioflotation: Additional mechanisms studied for low-grade ores and mine tailings.​

What differentiates biological from chemical approaches is the operating philosophy. Conventional hydrometallurgy uses strong inorganic acids (sulfuric, hydrochloric, nitric) at high temperatures, generating large volumes of hazardous waste. Biomining operates largely at ambient conditions, using biodegradable lixiviants (liquid chemical solutions used in hydrometallurgy to selectively extract metals from ore or recycled materials by dissolving them into a liquid phase)21, with significantly reduced freshwater consumption and wastewater generation.

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Urban Biomining
It is the recovering of critical resources from the waste streams of cities and industrial systems rather than from natural ores.2223 A 2025 review published in ACS Environmental Au by researchers at George Washington University identifies it as one of the most promising frontiers in sustainable REE recovery.24

Laboratory studies have demonstrated impressive bioleaching yields. Acetic acid achieves leaching efficiencies exceeding 90% for neodymium, dysprosium, and praseodymium from NdFeB magnet powder at concentrations of 1.6–10 mol/L and 60°C.2526 Citric acid at 1 mol/L can achieve near-complete (100%) REE leaching from hydrogen-decrepitated (a process used to create extremely small grains)27 NdFeB powder within 24 hours.28 Importantly, the spent culture medium of microorganisms  (or supernatant, which is the byproduct liquid remaining after microorganisms have grown, containing metabolic waste, secreted proteins, and residual nutrients)29 often outperforms isolated organic acids, because it contains a richer diversity of leaching agents at higher combined concentration.3031​

A two-step bioleaching process using acidophilic bacteria on e-waste shredded dust was found to mobilise up to 99% of cerium, europium, and neodymium, and up to 80% of yttrium and lanthanum within eight days.32 A sequential microbial process pairing bacterial bioleaching with microalgal biosorption has demonstrated the feasibility of recovering multiple REEs (gadolinium, praseodymium, cerium, lanthanum) from e-scraps.33

Beyond e-waste, biomining offers a pathway into legacy waste. Coal ash, the residue from burning coal, is one of the most REE-rich and economically promising secondary sources.34 A techno-economic analysis cited in a 2024 comprehensive review found that coal ash yields the highest profitability of all mining waste streams when subjected to biomining recovery.35 Old mine tailings, the rock and mineral residues left behind after primary extraction, also retain significant REE concentrations.3637 Biomining these sites simultaneously addresses long-term environmental hazards, reducing acid drainage and radioactive residue exposure, while turning environmental liabilities into resource streams.3839

Selectivity
Since rare earth elements are chemically near-identical, so finding just one among the 17 is a complex process, and can require hundreds of solvent extraction stages via conventional methods.40

This is where molecular biology can help.

In 2018, researchers discovered lanmodulin (LanM)41, a small (~12 kDa- according to Google AI, a teaspoon holds over 200 quintillion particles)42 bacterial protein produced by methylotrophic bacteria that is able to select the required REE to a degree no synthetic chemical method can yet do.43 It also remains stable at pH 2.5 and temperatures up to 95°C, making it practically viable in the acidic, hot conditions of industrial leachates (industrial leachates are the highly contaminated, toxic liquids formed when water percolates through industrial waste, landfills, or contaminated sites, dissolving soluble materials)44.43

Beyond lanmodulin, the field has expanded to include:

  • Lanthanide-binding peptides (LBPs)45: Short synthetic sequences that selectively adsorb specific REEs with minimal cross-reactivity for neighboring non-REE elements​
  • Functional nucleic acid aptamers46: A DNA aptamer (Sc-1) has demonstrated the ability to bind REE ions selectively and discriminate all 17 REEs into three groups.​
  • Pyrroloquinoline quinone (PQQ)47: A microbial cofactor that can precipitate REEs from solution and has a natural preference for light REEs over heavy ones​
  • Lanthanide-binding phage (LBPh)48: M13 bacteriophage engineered with ~3,300 copies of an LanM-derived peptide, achieving 35 mg/g binding capacity with preferential uptake of heavy REEs and pH-triggered release over five reuse cycles​

Don’t look at me, I cannot pronounce these words either. I was researching urban mining and fell into this black rabbit hole.

What biomining-enabled circular REE recovery ultimately points toward is not merely a more efficient way to recycle old phones. It is a fundamentally different relationship between industrial civilisation and the material world, one in which the waste of one cycle becomes the feedstock of the next, in which biology does the discriminating work that chemistry does badly and expensively, and in which the geopolitical concentration of a critical resource is loosened by distributing recovery capacity to wherever waste accumulates.

This vision aligns with what some materials scientists and industrial ecologists call a regenerative materials system49: one that does not merely reduce harm but actively restores, cleaning up legacy pollution in mine tailings and coal ash while simultaneously supplying the materials a decarbonizing economy urgently needs. The circular economy of REEs through biomining represents exactly this kind of convergence: biotechnology, sustainability science, and critical materials security not pulling in different directions, but pointing the same way.

The technology is not yet ready for full industrial deployment. But the science has reached the point where the question is no longer whether it is possible, but how fast we choose to make it happen.

Sources

  1. Rare Earth Elements — MIT Earth Systems Initiative
  2. Rare Earth Element Deposits — USGS / Geology.com
  3. Urban Biomining of Rare Earth Elements: Current Status and Future Opportunities — PubMed
  4. Environmental Impacts of Rare Earth Element Mining and Strategies for Mitigation — ScienceDirect
  5. China Continues to Dominate Rare Earths as Diversification Efforts Gain Momentum — Mining Technology
  6. China Could Use Rare Earths as a Weapon in the Trade War, State Media Warns — Reuters (2019)
  7. China Hits Back at US Tariffs with Export Controls on Key Rare Earths — Reuters (2025)
  8. China’s New Rare Earth and Magnet Restrictions Threaten US Defense Supply Chains — CSIS
  9. China Tightens Export Controls on Rare-Earth Metals: Why This Matters — Al Jazeera
  10. US-China Trade Pause Framework 2025: Diplomatic Analysis — Discovery Alert
  11. China to Suspend Some Rare-Earth Curbs and US Chip Firm Probes — Bloomberg
  12. The Global E-Waste Monitor 2024 — Global E-Waste Statistics Partnership
  13. A Record 62 Million Tonnes of E-Waste Produced in 2022 — ITU Press Release
  14. Rare Earth Recycling: Promise Meets Reality in the Race for Sustainable Supply Chains — Rare Earth Exchanges
  15. Powering the Energy Transition’s Motor: Circular Rare Earth Elements — McKinsey & Company
  16. Rare Earth Elements Briefing Note — The Geological Society of London
  17. Understanding Rare Earth Elements (REEs) — KP Growth
  18. A Review of the Occurrence and Recovery of Rare Earth Elements from E-Waste — PMC
  19. Urban Biomining of Rare Earth Elements: Current Status and Future Opportunities (Full Text) — PMC
  20. Biomining for Sustainable Recovery of Rare Earth Elements from Mining Waste: A Comprehensive Review — Science of the Total Environment
  21. What Are Lixiviants and Solutions in Hydrometallurgy? — MiningDoc
  22. Urban Biomining — Bio-Based Press
  23. Sustainable Recovery of Critical Metals from Urban Waste Streams — Journal of Environmental Management / ScienceDirect
  24. Urban Biomining of Rare Earth Elements: Current Status and Future Opportunities — PubMed
  25. Evaluating Organic Acids as Alternative Leaching Reagents for NdFeB Permanent Magnets — Journal of Rare Earths / ScienceDirect
  26. Leaching Performance of Various Agents and Microbial Platforms for E-Waste Treatment (Table 1) — PMC
  27. Decrepitation — Ideal Magnet Solutions
  28. Leaching and Recovery of Rare-Earth Elements from Neodymium Magnet Waste Using Organic Acids — DOAJ / Metals (2018)
  29. What Is a Supernatant? — News-Medical Life Sciences
  30. Bioleaching of Rare Earth Elements from Waste Phosphors Using Organic Acids — U.S. DOE / OSTI
  31. Rare Earth Elements Biorecovery from Mineral Ores and Industrial Waste — IntechOpen
  32. Bioleaching of Metals from WEEE Shredding Dust — PubMed / Journal of Hazardous Materials (2018)
  33. Microbial Biominers: Sequential Bioleaching and Biouptake of Metals from Electronic Scraps — PMC / MicrobiologyOpen (2022)
  34. Sustainable Recovery of Rare Earth Elements from Coal and Coal Ash through Urban Mining — Journal of Environmental Management / ScienceDirect
  35. Biomining for Sustainable Recovery of Rare Earth Elements from Mining Waste: A Comprehensive Review — Science of the Total Environment
  36. Can Rare Earth Elements Be Recovered from Abandoned Mine Tailings? — PMC / Environmental Science and Pollution Research (2024)
  37. Tailings Valorisation: Opportunities to Secure Rare Earth Supply — Journal of Cleaner Production / ScienceDirect
  38. Biomining for Sustainable Recovery of Rare Earth Elements from Mining Waste: A Comprehensive Review — Science of the Total Environment
  39. Recent Advances on Tailing Management to Prevent Pollution from Rare Earth Mine Tailings — PMC / IJERPH (2022)
  40. Separation Hydrometallurgy of Rare Earth Elements — Zhang et al., Springer (2016)
  41. Lanmodulin: A Highly Selective Lanthanide-Binding Protein from a Lanthanide-Utilizing Bacterium — JACS (2018)
  42. Mechanically and Chemically Robust Lanmodulin-Functionalized Silk Scaffolds for REE Recovery — U.S. DOE / OSTI
  43. Selective and Efficient Biomacromolecular Extraction of Rare-Earth Elements Using Lanmodulin — PubMed / ACS Inorganic Chemistry (2020)
  44. Emissions from Waste Management Facilities — European Environment Agency
  45. Bioadsorption of Rare Earth Elements through Cell Surface Display of Lanthanide-Binding Tags — PMC / Environmental Science & Technology (2016)
  46. Kinetic and Affinity Profiling of Rare Earth Metals Using a DNA Aptamer — JACS (2024)
  47. The Earlier the Better: Structural Analysis and Separation of Lanthanides with Pyrroloquinoline Quinone — PubMed / Angewandte Chemie (2020)
  48. Virus-Based Separation of Rare Earth Elements — ACS Nano Letters (2024)
  49. Regenerative System — ScienceDirect Topics

E-waste – I: The Problem

I’ve worked for a couple of projects on e-waste and e-waste recycling, and I wanted to revise that and see what’s going on in the space, so here is a series of posts about these topics.

In 2022, the world generated 62 million tonnes of electronic waste. Only 22.3% of that waste was properly recycled. By 2030, we’re on track to hit 82 million tonnes annually—while our recycling rate is projected to drop to 20%.12 The gap between what we’re throwing away and what we’re recovering isn’t just an environmental problem. It’s an economic disaster not even bothering to hide, and yet few pay attention. That 62 million tonnes of waste contains an estimated $62 billion worth of recoverable materials—gold, silver, copper, rare earth metals—currently rotting in landfills or being processed in unsafe conditions.2

EEE
E-waste, according to the European Union’s WEEE (Waste Electrical and Electronic Equipment) Directive, is “equipment which is dependent on electric currents or electromagnetic fields in order to work properly”.3 India’s E-Waste Management Rules 2022 define it as “electrical and electronic equipment, whole or in part discarded as waste by the consumer or bulk consumer as well as rejects from manufacturing, refurbishment and repair processes”.4 The US Environmental Protection Agency divides e-waste into ten broad categories:5​

  1. Large household appliances: refrigerators, air conditioners, washing machines
  2. Small household appliances: toasters, coffee makers, vacuum cleaners
  3. IT equipment: computers, laptops, monitors, printers
  4. Consumer electronics: televisions, smartphones, tablets, gaming consoles
  5. Lamps and luminaires: LED bulbs, fluorescent tubes
  6. Toys: electronic games, remote-controlled cars
  7. Tools: power drills, electric saws
  8. Medical devices: blood pressure monitors, glucose meters
  9. Monitoring and control instruments: thermostats, smoke detectors
  10. Automatic dispensers: vending machines, ATMs

And critically, this includes batteries of all types:6

  1. Alkaline and zinc-carbon batteries: the everyday AA, AAA batteries we use in remotes and toys​
  2. Lithium-Ion batteries (Li-ion): found in smartphones, laptops, electric vehicles—these have high energy density and long life, but are highly reactive and flammable​
  3. Lead-acid batteries: used in vehicles and industrial applications—low cost but heavy and toxic
  4. Nickel-cadmium batteries (NiCd): known for consistent performance but containing toxic cadmium

Why should we recycle e-waste?
Why not? Electronics contain both valuable materials and dangerous ones, and throwing them away is economically silly and environmentally irresponsible. For one, recovering gold produces 80% less carbon emissions than primary mining.7 Recycling lithium-ion batteries instead of mining new metals reduces greenhouse gas emissions by 58-81%, water use by 72-88%, and energy consumption by 77-89%.8910 If we extend the lifespan of existing devices—through repair, reuse, and high-quality refurbishment—we drastically reduce the need to manufacture new ones.

Hazard
Electronic devices are chemical cocktails. Circuit boards, batteries, and screens contain an array of hazardous substances:111213

  • Lead: damages the nervous system, kidneys, and reproductive system. Particularly harmful to children’s developing brains. Found in cathode ray tubes (those old bulky TVs and monitors) and soldering materials.
  • Mercury: a potent neurotoxin that accumulates in the body, causing neurological and developmental issues. Present in flat-screen displays, fluorescent lamps, and some batteries.
  • Cadmium: linked to kidney damage, lung cancer, and bone disease. Found in rechargeable NiCd batteries, old CRT screens, and printer drums.
  • Chromium (specifically hexavalent chromium): a recognized carcinogen that can cause lung cancer, respiratory issues, and skin irritation. Extremely soluble, so it easily contaminates groundwater.
  • Brominated flame retardants: used in plastic components to prevent fires, but they release toxic dioxins when burned or heated. These cause hormonal disorders.​
  • Beryllium: found in power supply boxes. Exposure can cause chronic lung disease.

The World Health Organization has identified e-waste as one of the fastest-growing solid waste streams posing serious health risks.14 When e-waste is dumped in landfills, these toxic materials leach into soil and groundwater. When it’s burned—as happens in much of the informal recycling sector—they’re released into the air as poisonous gases. Studies in communities near informal e-waste recycling sites show elevated rates of respiratory illnesses, cardiovascular problems, neurological disorders, and cancers. Children and pregnant women are particularly vulnerable.1516

Urban Mining
Electronics are concentrated sources of valuable materials—far more concentrated than their natural ore deposits:171819

  • Gold: one tonne of circuit boards contains approximately 350 grams of gold. To put that in perspective, the gold content in circuit boards is 800 times higher than in natural gold ore. Mining one tonne of gold ore might yield just 5 grams of gold; circuit boards yield 350 grams.
  • Silver: that same tonne contains about 2 kilograms of silver.
  • Copper: 120 kilograms per tonne of circuit boards.
  • Other precious metals: aluminum, platinum, cobalt, palladium, rare earth elements.

To make this concrete: recycling one million cell phones can yield approximately 35,000 pounds of copper, 772 pounds of silver, and 75 pounds of gold. The total value of recoverable materials from global e-waste in 2022 was estimated at $62 billion.19 This is what researchers call “urban mining”—recovering valuable materials from discarded electronics rather than extracting them from the earth.20

If e-waste is valuable, dangerous, and growing, why is it still handled so badly? The answer isn’t technology or awareness. It’s incentives—and the policy instrument meant to fix this problem may be quietly making it worse. In the next post, I’ll unpack EPR (Extended Producer Responsibility) — the policy tool we’ve pinned our hopes on, and why it’s not delivering what it promises yet.

Sources

  1. 50+ E-Waste Statistics 2026
  2. Electronic Waste Rising Five Times Faster Than Documented E-Waste Recycling – UN
  3. Waste Electrical and Electronic Equipment (WEEE) Statistics – Eurostat Metadata
  4. E-Waste (Management) Rules, 2022 – Government of India (English)
  5. A Study on E-Waste Management (IJCRT25A6202)
  6. Types of E-Waste – The Ultimate Guide One Must Know
  7. Urban Mining & Metal Recovery – Specialty Metals Recycling
  8. Recycling Batteries Helps Recover Critical Metals
  9. Advanced Lithium Recovery Technology for a Sustainable Future
  10. Recycling Lithium-Ion Batteries Cuts Emissions and Strengthens Supply Chain
  11. Health Consequences of Exposure to E-Waste
  12. Hazardous Substances in E‑Waste
  13. E‑Waste and Hazardous Elements (IJISRT24OCT1008)
  14. Electronic Waste (E‑Waste) – WHO Fact Sheet
  15. The Growing Environmental Risks of E‑Waste
  16. Impact of E‑Waste on Human Health and Environment
  17. Refining Gold and Copper from E‑Waste
  18. Five Reasons Why E‑Waste Recycling Is Important
  19. What Is E‑Waste Parts Recovery? Steps, Benefits, and More
  20. What Is Urban Mining?