Copper Recovery from PCBs by Acidithiobacillus ferrooxidans : Toxicity of Bioleached Metals on Biological Activity
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ORIGINAL PAPER
Copper Recovery from PCBs by Acidithiobacillus ferrooxidans: Toxicity of Bioleached Metals on Biological Activity E. Benzal1 · A. Cano2 · M. Solé1 · C. Lao‑Luque1 · X. Gamisans1 · A. D. Dorado1 Received: 15 November 2019 / Accepted: 20 March 2020 © Springer Nature B.V. 2020
Abstract The suitability and limits of bioleaching for copper recovery from printed circuits boards has been stated with new strategies and methodologies. The process has been tested using a continuous column reactor simulating those conditions found at industrial scale. The new strategy developed improved the kinetic reaction rate and overcomes transport limitations for the leaching solution, thus improving copper recoveries from 50 to 80% in only 6 h. This drastically reduced the time required by previous studies to achieve the same copper recovery. Inhibition effects of the biological process due to the release of metals from e-waste has been identified by means of microrespirometric monitoring tests. This systematic study allowed identifying that nickel, copper and aluminum impact the microorganisms’ activity, inactivating them in specific scenarios (depending on the concentration and the time exposed). Including the time exposure as variable, this work demonstrated that metal concentrations that have been reported as non-toxic to microorganisms, resulted toxic when the required leaching contact time was considered. Besides high iron concentrations also produce inhibitory effect on the microorganisms’ growth, despite being the energy source for their metabolism. Graphic Abstract
Keywords Biological leaching · Electronic waste · Printed circuit boards · Valorisation · Column · Respirometry * A. D. Dorado [email protected] 1
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Department of Mining, Industrial and ICT Engineering, Universitat Politècnica de Catalunya, 08242 Manresa, Barcelona, Spain Faculty of Exact, Natural and Agricultural Sciences, Universidad de Santander, Bucaramanga, Santander 680003, Colombia
Statement of Novelty Bioleaching has gained importance over the past few years as a sustainable alternative for metals recovery from e-waste. The current aim is to recover valuable metals at competitive speed with lower energetic expenditure and lower
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environmental impact. In this context, different strategies have been tested to increase the efficiency of copper recovery from e-waste. Given the complex composition of the e-waste, the metals solubilized in the process could affect the biological process, inhibiting the activity of the microorganisms. Therefore, the toxic effect that some bioleached metals have on the microorganisms has been also evaluated. Although this aspect is not usually taken into account when the bioextraction process is studied, this could limit the applicability of the technology.
Introduction Over recent decades, both rapid technology development and ever-shortening lifespans have contributed to increase the need for electronic waste (e-waste) disposal. e-waste is the type of waste that is
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