The BioCuInGe project set out to convert copper‑dust waste from smelting operations into valuable resources by recovering germanium, indium and copper through a combination of chemical leaching and biologically inspired sorption. The copper dust, supplied by Hindustan Zinc Limited and Hindustan Copper Limited, contains not only copper but also trace amounts of germanium and indium, elements that are critical for high‑technology applications yet are not currently recovered from such waste streams. The research team focused on characterising the mineralogy of the dust, optimizing alkaline leaching conditions, and then selectively binding the target metals with high‑affinity siderophores and engineered peptides.

Chemical leaching experiments were carried out in 50 mM citrate buffer at pH 3.9, a condition that maximised the solubility of copper while keeping germanium and indium in solution. Subsequent biosorption steps employed phage‑displayed peptide libraries that were screened for metal‑binding specificity. Isothermal titration calorimetry revealed strong binding affinities for the selected peptides, with dissociation constants in the low micromolar range for Fe(III), Ge(IV) and In(III). Mass spectrometry confirmed the formation of stable metal‑peptide complexes, and immobilisation of the peptides on solid supports allowed for repeated use without significant loss of activity. Flotation tests on selected copper dust samples demonstrated that the recovered copper could be separated from the leachate with a purity exceeding 99 %, while the metal‑laden peptides could be regenerated to recover germanium and indium in a second stage. Overall, the integrated process achieved recoveries of up to 85 % for copper, 70 % for germanium and 60 % for indium under laboratory conditions, meeting the project’s target of reaching Technology Readiness Level 4–5.

The project’s scientific outcomes also included detailed thermodynamic characterisation of the metal‑binding interactions. Tables summarising the enthalpy and entropy changes for Fe(III) and Fe(II) binding to the peptides were produced, providing a foundation for future scale‑up studies. The research team identified key parameters that influence binding selectivity, such as buffer composition, pH, and the presence of competing ions, and used this knowledge to refine the leaching protocol. The work also produced a set of high‑affinity peptides that can be further engineered for industrial application, and the team has filed patents covering the peptide sequences and their use in metal recovery.

Collaboration was central to the project’s success. The German partners comprised the Helmholtz Institute Freiberg for Resource Technology (HIF) and the engineering firm G.E.O.S. Ingenieurgesellschaft mbH, which led the chemical leaching and metal recovery phases. The Indian partners were the Department of Biochemical Engineering and Biotechnology at the Indian Institute of Technology Delhi (IIT Delhi) and Lakshmi Life Sciences, which provided the copper‑dust samples and conducted the initial characterisation and biosorption screening. Dr. Ziauddin Ahammad of IIT Delhi and Dr. Katrin Pollmann of HZDR co‑directed the project, ensuring a balanced integration of chemical and biological expertise. The project ran from 2019 to 2022, with a key milestone meeting held in Frankfurt in June 2022 to review progress and plan the next steps. Funding was provided through a joint German–Indian research grant, likely under the auspices of the German Federal Ministry of Education and Research (BMBF) and Indian research agencies, reflecting the project’s alignment with India’s “waste‑to‑wealth” initiative and Germany’s interest in securing critical raw materials. The outcomes of BioCuInGe lay the groundwork for future scale‑up projects that aim to bring the technology to a commercial level, potentially achieving a Technology Readiness Level of 7 in subsequent phases.