Beyond biorecovery: environmental win-win by biorefining of metallic wastes into new functional materials (B3)

Lead Research Organisation: Bangor University
Department Name: Sch of Biological Sciences

Abstract

30 years' research on metal biorecovery from wastes has paid scant attention to strong CONTEMPORARY demands for (i) conservation of dwindling vital resources (e.g platinum group metals (PGM), recently rare earth elements, (REE), base metals (BMs) and uranium) and (ii) the unequivocal need to extract/refine them in a non-polluting, low-energy way.
21stC technologies increasingly rely on nanomaterials which have novel properties not seen in bulk materials. Bacteria can fabricate nanoparticles (NPs), bottom up, atom by atom, with exquisite fine control offered by enzymatic synthesis and bio-scaffolding that chemistry cannot emulate. Bio-nanoparticles have proven applications in green chemistry, low carbon energy, environmental protection and potentially in photonic applications. Bacteria can be grown cheaply at scale for facile production.
We have shown that bacteria can make nanomaterials from secondary wastes, yielding, in some cases, a metallic mixture which can show better activity than 'pure' nanoparticles. Such fabrication of structured bimetallics can be hard to achieve chemically.
For some metals like rare earths and uranium (which often co-occur in wastes) their biorecovery from scraps e.g. magnets (rare earths) and wastes (mixed U/rare earths), when separated, can make 'enriched' solids for delivery into further commercial refining to make new magnets (rare earths) or nuclear fuel (U). Biofabricating these solids is often beyond the ability of living cells but they can form scaffolds, with enzymatic processes harnessed to make biomineral precursors, often selectively.
B3 will invoke tiered levels of complexity, maturity and risk. (i) Base metal mining wastes (e.g. Cu, Ni) will be biorefined into concentrated sludges for chemical reprocessing or alternatively to make base metal-bionanoproducts. (ii) Precious metal wastes will be converted into bionanomaterials for catalysis, environmental and energy applications. (iii) Rare earth metal wastes will be biomineralised for enriched feed into further refining or into new catalysts. (iv) Uranium-waste will be biorefined into mineral precursors for commercial nuclear fuels.
In all, the environment will be spared dual impacts of both primary source pollution AND the high energy demand of processing from primary 'crude'.
Metallic scraps are tougher, requiring acids for dissolution. Approaches will include the use of acidophilic bacteria, use of alkalinizing enzymes or using bacteria to first make a chemical catalyst (benignly) which can then convert the target metal of interest from the leachate into new nanomaterials (a hybrid living/nonliving system, already shown). Environmentally-friendly leaching & acids recycle will be evaluated and leaching processes optimised via extant predictive models.
The interface between biology, chemistry, mineralogy and physics, exemplified by nanoparticles held in their unique 'biochemical nest', will receive special focus, being where major discoveries will be made; cutting edge technologies will relate structure to function, and validate the contribution of upstream waste doping or 'blending'; these, as well as novel materials processing, will increase bio-nanoparticle efficacy.
Secondary wastes to be biorefined will include magnet scraps (rare earths), print cartridges (precious metals), road dusts (PMs, Fe,Ce) & metallurgical wastes (mixed rare earths/base metals/uranium). Their complex, often refractory nature gives a higher 'risk' than mine wastes but in compensation, the volumes are lower, & the scope for 'doping' or 'steering' to fabricate/steer engineered nanomaterials is correspondingly higher.
B3 will have an embedded significant (~15%) Life Cycle Analysis iterative assessment of highlighted systems, with end-user trialling (supply chains; validations in conjunction with an industrial platform). B3 welcomes new 'joiners' from a raft of problem holders brought via Partner network backup.

Planned Impact

ENVIRONMENT will benefit (also UK plc) viz:

CO2 (from industry/power generation) is hard to 'value' in social/environmental 'costs' (Clarkson & Deyes H.M.Treasury working paper 140, 2002). The IPCC consensus of $9-$197/tonne CO2, is upheld in that report; mean value ~ $100/t CO2.
Umicore (smelter) processed (2004) 6430t secondary materials: 0.4t Pt/0.5tPd/0.1t Rh; the CO2 emission was 2207.5 t. (Saurat, 2006); its CO2 'value'/t metal would be $220,750. If B3 saves 1% of this CO2 (assuming 100 refineries worldwide) the 'value' of B3 becomes $2.2M in 10 years. Assuming 10% market penetration over 100 yrs that makes: $2.2B.

ENERGY: The corresponding energy consumption (Umicore) was 64 TJ (i.e additional CO2 burden of making grid electricity); considerable power savings (CO2 equiv) would be made by reduced energy consumption via adopting B3 biorefining

NUCLEAR EXPANSION. UK needs uranium (it has no primary resource); B3 mitigates against future price rises

LESS MINING: Total est. global CO2 emissions (kt CO2 equiv.) are: Cu: 52,466/Au, 31,298/Ag, 8,069/Fe, 8,011/Zn, 5,384/ Pt 3,204/Pd 2,237 (Material Security Report, RE KTN); a total of 110699 kt. At the est. 'value' in CO2 (above) this makes $11B. If B3 saves 10% of this demand this makes $1B.

For UK Plc: cheaper electricity (= global competitiveness). Our report (Royal Soc; Brian Mercer Sr. Award for Innovation) showed economics of making electricity from fuel cell bionanocatalyst (precious metals) biorefined from 10,000 t road dust - calculated from REAL DATA (factoring-in costs of biomass production + cost of making fuel cells):
Value of metals recovered (2008 prices) £356,000
Assume all of that went into fuel cells (3,865 of them @1 kW)
Value of electricity made (2008 prices) = £6M (i.e. what you pay) (£0.18/kWh)
Value if sold to Grid (2008 price) (i.e. what you supply) (£0.04/kWh) = £1.3M
Since 2010 with new feed in tariffs: electricity is sold from microgenerators to utilities at typical m rate of ~ 5 p/kWh. The value becomes £162.5M.

OVERSEAS: Use of biorefined precious metal catalysts in heavy oil upgrading; our economic calculations were ratified (J. Levie: letter supported a successful EPSRC bid):

Calculated extra oil with catalyst (billion barrels) is 200,000 bb/y/well.
Profit/barrel = $40 (£25) = £5M
50 mg catalyst/barrel; total needed = 10 kg
Road dust total/yr = 250,000 t
Catalyst available/yr = 200 kg
Annual potential profit just from UK derived road dust = £4.75 M
Assume UK generates 1/100 of total global recoverable road dust; potential profit (10 yrs) from JUST Petrobank = £4.75 B

GREEN CHEMISTRY (cleaner processes): Market research (Catalytic Technology Management Ltd; commissioned), highlighted niches for B3 catalysts in synthesis of platform chemicals (higher product selectivity, i.e. less waste). Particular to note is where there is no good commercial catalyst e.g. Au/Pd (selective oxidations with major applications in (e.g.) the fragrances market).

TOMORROWS Hi-TECH: Our recent findings (publ, 2012) show the surface of Bio-Pd nanoparticles is electron spin polarised- bringing novel applications in chirality (product selectivity: elusive in chemical technology) plus potential applications like hydrogen liquefaction; the cost of clean H2 is the single limiting factor for the Hydrogen economy (Brian Mercer Economic Report: above). H-Liquefaction is energy-expensive; cheap Pd catalyst would impact on market price of H2.

GEOPOLITICS: Base metals/rare earth metals/uranium: Prices are rising steeply, with major geopolitical issues (rare earths) of materials supply/security. Recovery from wastes/resource recycling are INESCAPABLE socio-economically. There is no current good refinery technology for these outside China; B3 is a chance for BIOrefining to get a head start hard over chemical refining; actual values will come from our life cycle analysis study. B3's technology would be sought globally.
 
Description Research to date has continued on two fronts, both of which have yielded positive data that has confirmed the original hypotheses of the Bangor section of the proposal (the potential for using microorganisms to extract economically-important metals from mineral wastes, and using new species of acid-tolerant sulfidogenic bacteria to both selectively capture metals and to synthesise particles with major technological potential)
Exploitation Route The metal mining sector (to enhance metal recovery and minimise environmental pollution). Environmental regulatory authorities (to remediate metal-contaminated waters).
Sectors Environment,Manufacturing, including Industrial Biotechology