Microorganisms have the potential to manufacture metallic nanoparticles, irrespective of the source of metal cations, and provide us with new particles with novel functions. To exploit this we are identifying and optimising genetic elements with an aim to increase nanoparticle production and control nanoparticle size and homogeneity; in effect standardising nanoparticle samples by using biology. Whilst developing this process we are exploring its application in the treatment of contaminated waste, water and land. For the former application we are working to remove copper from whisky distillery by-products and for the latter application we are part of a larger collaboration aiming to financially incentivise land decontamination. After using phytoremediation to hyperaccumulate metal contaminants from the soil, plants are harvested, processed and used as a source of metals for bacterial nanoparticle synthesis. Both applications illustrate how synthetic biology might contribute to moving us towards a more sustainable circular economy.