The Sublimus project explores innovative and circular approaches for the extraction of rare and precious metals from an underexploited resource: urban wastewater and, in particular, activated sludge. The program focuses on precious metals, gold and platinoids (PGMs), given the scarcity of geological resources for these elements and their roles in high-tech and energy transition technologies, which led the European Commission to classify PGMs, among others, as critical raw materials for its economic development. In this project, Meurice R&D explores biosorption technology using an industrial microbiological residue produced in large quantities, especially in Belgium: brewer’s yeast.
R&D Projects
SUBLIMUS
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The physicochemical principles of biosorption are numerous and complex: chelation, ion exchange, coordination, complexation, adsorption, micro-precipitation…they require in-depth knowledge of the microbial cell wall structure and its evolution according to conditions (ionic strength, pH, temperature), as well as the speciation of metallic elements in solution based on these same parameters. These different research aspects align with the multidisciplinary expertise of Meurice R&D. The work has led to a sustainable and economically viable solution for the recovery of dissolved gold contained in Brussels’ urban wastewater (Aquiris Station). The results suggest the recovery of 4 kg of gold/year by weekly investing one tonne of dry yeast. Extracting the same quantity from gold ore would require processing several thousand tonnes. The Sublimus project is the result of a collaboration between ULB, VUB, and Meurice R&D.
PRECIOUS
The PRECIOUS program is part of a circular “urban mining” dynamic, proposing a biological approach that reduces environmental impacts for the production of metallic raw materials. The project aims to develop a global technology for the valorization of printed circuit boards from PCs, laptops, and other electronic components by utilizing bacteria from extreme environments (originating, for example, from the acidic geysers of Yellowstone) that can dissolve metals such as copper, nickel, zinc, aluminum… and thus enrich waste with precious metals (mainly gold, present at 200-300 g/tonne).
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PRECIOUS aims to develop a combination of biological and chemical processes (while reducing the latter) to achieve an efficient yet flexible and modular technology that could offer a solution to clandestine operations occurring in countries where recycling is not controlled, leading to dramatic consequences for public health and the environment. The innovative approach would also enable local industrial development, close to the urban mine represented by a city like Brussels, without toxic fallout and by minimizing transportation.
In a first microbiological step, base metals (heavy metals) are extracted in liquid form through the action of acidophilic bacteria generating an oxidizing agent, the ferric ion. A significant challenge of the project is to reduce the chemical inputs of the process to make it autonomous or to consume only residual materials from other activities (such as sulfur from fuel treatment). Since the waste is then concentrated in gold, chemical extraction will require fewer reagents; this operation involved screening less impactful molecules such as thiourea to substitute toxic or dangerous agents like cyanide, aqua regia, etc. The recovery of the precious metal was also achieved biologically by utilizing a waste product from a typically Brussels activity: brewing. Yeast, a residue from the brewing process, indeed exhibits exceptional properties for the selective extraction of dissolved gold from a polymetallic leachate. The global nature of the envisioned process relies on the total valorization of all components of printed circuit boards: from heavy metals to precious metals, including plastics.