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Scaling up bioprocesses from the experimental to the pilot or industrial scale involves heuristics and scale relationships that are far from the specific phenomena and are usually not connected to the experimental data. In complex systems, the scaling-up methodology must connect the experimental data with the tools of engineering design. In this work, a two-stage gold bioleaching process was used as a case study to develop a mathematical model of bioprocess scaling that combines the design of experiments with dimensional analysis using the Buckingham Pi theorem to formulate a predictive model that allows scaling up bioprocesses. It was found that the C/N, C/K, and T/C ratios are dimensionless factors that can explain the behavior of a system. Using the Pearson Product–Moment bivariate analysis, it was found that the dimensionless factors C/N and C/K were correlated with the leaching potential of the fermented broth at 1060 cm−1. With these results, a non-linear logarithmic model based on dimensionless parameters was proposed to explain the behavior of the system with a correlation coefficient of R2 = 0.9889, showing that the optimal conditions to produce fermented broth comprised a C/N ratio close to 50 and a C/K ratio close to 800, which allows predicting the scaling of the bioprocess.

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This review paper explores the potential of bioleaching as a sustainable alternative for recovering metals from solid matrices. With over 12 billion tons of solid waste annually worldwide, bioleaching provides a promising opportunity to extract metals from solid waste, avoiding harmful chemical processes. It explains bacterial and fungal bioleaching techniques that extract copper, gold, zinc, and other metals from solid matrices. Fungal bioleaching effectively extracts a wide range of valuable metals, including nickel, vanadium, aluminium, molybdenum, cobalt, iron, manganese, silver, platinum, and palladium. The review highlights different solid matrices with metal contents that have the potential to be recovered by bioleaching, presenting promising bioprocess alternatives to current industrially available technologies for metal recovery. The optimal conditions for bioleaching, including pH, temperature, agitation–aeration, and pulp density are also discussed. The review shows that bioleaching has the potential to play a crucial role in the transition to a more sustainable and circular economy by providing an efficient, cost-effective, and environmentally friendly method for metal recovery from solid matrices.

The fique plant (Furcraea sp.) is a native plant of the Andean region with a great capacity to adapt to different environmental conditions, of which only 4% of the plant is used for developing natural fibers. The comprehensive use of fique and its by-products represents a source of opportunities for the industry and can play an important role in achieving sustainable development. The available literature suggests that fique fiber, juice, and bagasse could boost sectors such as agriculture, construction, the pharmaceutical industry, power generation, and the development of environmental solutions, among others. This review article could help researchers to understand the fique production system, introduces research experiences, and analyze the potential of recent developments for the industry.