Copper Recovery from PCBs by Acidithiobacillus ferrooxidans: Toxicity of Bioleached Metals on Biological Activity

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 hours. 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.

Microbial Processing of Waste Shredded PCBs for Copper Extraction Cum Separation—Comparing the Efficacy of Bacterial and Fungal Leaching Kinetics and Yields

“…Thus, the PCBs slurry pH was lowered to <1.5 before adding the microbial inoculum by using 2N sulfuric acid. A. ferrooxidans oxidizes ferrous to ferric form and A. thiooxidans has the inherent ability to oxidize the elemental sulfur (S°) to produce H2SO4 [20,[37][38][39][40]. It was reported earlier that A. niger produces different kinds of organic acids like citric acid, oxalic acid, gluconic acid when the growth medium is enriched with sucrose as the source of energy [41][42][43].…”

Microflow Injection System for Efficient Cu(II) Detection Across a Broad Range

“…One such approach is bioleaching, which harnesses the activity of specific microorganisms to generate leaching agents capable of extracting metals. Although bioleaching has found success in the mining industry for lowgrade ores [2], such as in commercial bio-heap processes [3,4], its potential for large-scale metal recovery from e-waste [5,6] is currently under exploration.…”

Microflow injection analysis based on modular 3D platforms and colorimetric detection for Fe(III) monitoring in a wide concentration range

“…Among these is the bioleaching process, which is based on the activities of certain microorganisms that generate a leaching agent responsible for metal extraction. Bioleaching is currently employed in the mining industry for low-grade ores [ 2 ], such as in bio-heap processes for commercial applications [ 3 , 4 ], but it may also be effective in the industrial-scale recovery of metals from e-waste [ 5 , 6 ].…”