Metals have a finite supply, thus metal scarcity and supply security have become worldwide issues. We have to ensure that we do not drain important resources by prioritizing the desires of the present over the needs of the future. To solve such a global challenge we need to move to a circular, more sustainable economy where we use the resources we have more wisely. One of the founding principles of a circular economy is that waste is an unused feedstock; that organic and inorganic components can be engineered to fit within a materials cycle, by the design, engineering and re-purposing of waste streams. In this fellowship I propose to design and engineer bacteria to repurpose our waste streams for us. I plan to use the new tools and techniques provided by advances in biology to engineer a microbe with the ability to upcycle critical metal ions from waste streams into high value nanoparticles. Certain bacteria have the ability to reduce metal cations and form precipitates of zero-valence, pure metals, as part of their survival mechanism to defend against toxic levels of metal cations. I will adopt the modular approach used in Synthetic Biology alongside iterative design, build and test cycles in order to enhance, manipulate and standardise the biomanufacture of these nanosize precipitates as high value products. With training in life cycle assessment, I will determine the financial benefits for business of adopting biological waste treatment methods with high value resource recovery and I will provide biogenic material to other researchers (academic and industrial) free of charge to encourage user pull for the technology.