Abstract. Over the past 30 years the literature has burgeoned with bioremediation approaches to heavy metal removal from wastes. The price of base and precious metals has dramatically increased. With the resurgence of nuclear energy uranium has become a strategic resource. Other 'non-carbon energy' technologies are driven by the need to reduce CO 2 emissions. The 'New Biohydrometallurgy' we describe unites these drivers by the concept of conversion of wastes into new materials for environmental applications. The new materials, fashioned, bottom-up, into nanomaterials under biocontrol, can be termed 'Functional Bionanomaterials'. This new discipline, encompassing waste treatment along with nanocatalysis or other applications, can be summarized as 'Environmental Bionanotechnology'. Several case histories illustrate the scope and potential of this concept.

Batch-grown cells and continuously-grown biofilm of a Serratia sp. were utilized to recover the rare earth elements (REEs) lanthanum and neodymium from solution.Selectivity was obtained for La(III) over Th(IV) using columns of polyacrylamide gelimmobilized cells challenged at a rapid flow rate, exploiting the different solution chemistries and behaviors of REEs(III) and Th(IV). Biofilm-grown cells had a tenfold higher activity of the mediating phosphatase, which promotes metal deposition as the corresponding metal phosphate, reflected as a correspondingly enhanced level of removal of Nd(III) (as NdPO 4 ) in flow-through columns utilizing biofilm on reticulated foam. The biofilms retained activity in the removal of Nd(III) for > 1 year, losing activity exponentially with a half life of 3 months. The flow rate giving 50% removal (FA 1/2 ) of Nd(III) by 3 month old biofilms at pH 5.5 was 272 and 275 mL/h using two independent biofilm preparations, equivalent to a FA 1/2 of 34 column volumes/h for fresh biofilms. The removal of Nd(III) was sustained at pH down to 3.5 with approx. 20% of the column activity lost upon return to pH 5.5. A similar result occurred in the presence of the common REE leaching agent ammonium sulfate (100 mM), this did not affect the ability of Serratia sp. to recover REEs. With a view to the potential for future biomanufacturing of Nd(III)-catalyst, the deposited material was identified as NdPO 4 by X-ray powder diffraction with a nanoparticle size of 14.5 nm, irrespective of the biofilm age.Key phrases: neodymium biorecovery, lanthanum biorecovery, selective rare earth biorecovery, continuous flow process, immobilized Serratia biofilm, nanocrystallite harvest.

With the aim to recover precious metals (PMs) from spent automotive catalyst leachates into new catalysts, cells of E. coli first reduced Pd(II) or Pt(IV) physiologically to nanoparticulate cellbound Pd(0) and Pt(0). Metallised cells were then used as chemical catalysts for the reductive recovery of precious metals from model solutions and from aqua regia leachates of crushed spent automotive catalyst. Metal removal, which was slower from real leachate due to interference by other contaminants, was complete after 60 h. Biofabricated PM catalyst from waste reduced 0.5 mM Cr(VI) to a similar extent to commercial 5% Pd catalyst but at ~ half the rate. The hydrogenation of 2-pentyne was examined using commercial Pd on Al2O3 catalyst and biofabricated Pd/Pt catalyst, the latter showing more than 3-fold enhanced selectivity towards the desired cis-pentene product. Hence, biorefined PMs offer a clean route to waste treatment and effective neo-catalyst biomanufacture.

Dissimilatory reduction of sulfate, mediated by various species of sulfate-reducing bacteria (SRB) and a few characterized species of archaea, can be used to remediate acid mine drainage (AMD). Hydrogen sulfide (H 2 S/HS À ) generated by SRB removes toxic metals from AMD as sulfide biominerals. For this, SRB are usually housed in separate reactor vessels to those where metal sulfides are generated; H 2 S is delivered to AMD-containing vessels in solution or as a gas, allowing controlled separation of metal precipitation and facilitating enhanced process control. Industries such as optoelectronics use quantum dots (QDs) in various applications, e.g. as light emitting diodes and in solar photovoltaics. QDs are nanocrystals with semiconductor bands that allow them to absorb light and re-emit it at specific wavelength couples, shifting electrons to a higher energy and then emitting light during the relaxation phase. Traditional QD production is costly and/or complex. We report the use of waste H 2 S gas from an AMD remediation process to synthesize zinc sulfide QDs which are indistinguishable from chemically prepared counterparts with respect to their physical and optical properties, and highlight the potential for a empirical process to convert a gaseous "waste" into a high value product.