Agromining from Secondary Resources: Recovery of Nickel and Other Valuable Elements from Waste Materials

Industrial activities produce a variety of metal-rich waste, which are often classified as hazardous due to high concentrations of metals such as Ni, Zn, Cu, Cr, Pb and Cd. Metals recycling from waste materials is still limited, especially from those waste types characterized by complex matrices and multi-metal contamination, with large amounts of metal-rich waste materials being discharged into the environment. Although several pathways of metal recovery from waste have been developed, landfilling often remains the most convenient alternative in terms of costs. In recent years, a new approach to metals recycling from waste materials has been investigated: agromining with hyperaccumulator plants on waste-derived substrates. Hyperaccumulator plants can isolate specific metals from multi-metal waste matrices and bioconcentrate target metals in their biomass. Specific characteristics of industrial waste might limit plant establishment and uptake of target metals; thus, the addition of amendments is required prior to plant cultivations as well as the construction of waste-derived artificial substrates. Research conducted to date has shown limited effectiveness of agromining when applied on certain metal-rich industrial waste materials, while promising results were obtained from other types of waste. Upscaling trials are currently underway to demonstrate the applicability of waste agromining for metals recycling within waste generation industrial facilities.