Turning Automotive Waste into Value: Bioleaching Iron and Zinc with Acidithiobacillus thiooxidans
Published in Bioengineering & Biotechnology
The ever-growing need for sustainable metal recovery has prompted scientists to explore low-energy biotechnological solutions. In this study, we report the successful use of Acidithiobacillus thiooxidans to remove 99% of zinc and iron from galvanized steel waste generated by the automotive industry in Mexico.
Using Starkey medium and mild incubation conditions, the process achieved full metal removal within 72 hours. This biotreatment also resulted in the production of sulfuric acid and sulfate, confirming sulfur oxidation as the driving mechanism. Compared to traditional methods, this bioleaching approach is faster, cleaner, and more energy-efficient—offering a scalable alternative for industrial waste valorization.
This work is the first to demonstrate complete recovery of Zn and Fe from galvanized automotive waste using A. thiooxidans, highlighting the promise of microbial biotechnology in addressing global sustainability challenges through circular economy strategies.
Methods and Results Summary
Acidithiobacillus thiooxidans, an acidophilic sulfur-oxidizing bacterium, was cultured in Starkey medium adjusted to pH 3 and supplemented with elemental sulfur. Galvanized steel waste from the automotive industry (Interacero S.A. de C.V.) was milled and sieved to a particle size of 2 mm. Bioleaching experiments were conducted using 0.5% (w/v) of solid waste in 125 mL Erlenmeyer flasks containing 30 mL of medium and inoculated with 3×10⁸ CFU/mL of the bacterium. Flasks were incubated at 30 °C and 180 rpm for 7 days.
Metal concentrations were measured by ICP-OES before and after treatment. A complete (99-100%) removal of iron and zinc was achieved within 72 hours. Additionally, sulfate levels increased steadily (up to 20,161 mg/L), and sulfuric acid reached 0.2 M by 168 hours. The drop in pH confirmed active microbial sulfur oxidation driving the bioleaching process.
👉 Read more about how microbial metabolism is redefining waste treatment and resource recovery.
https://camjol.info/index.php/NEXO/article/view/15994
#Bioleaching #CircularEconomy #EnvironmentalBiotech #SustainableMining #MetalRecovery #SpringerNatureCommunities
Dr. Grisel Fierros-Romero is a researcher and academic leader specializing in environmental microbiology, marine microbiology, biotechnology, and bio-nanotechnology. Currently, she leads advanced research projects on marine microbiology and microbial ecology. Her research focuses on understanding the interactions of micro-predators, such as predatory bacteria, protists, and viruses, and their critical role in the microbial loop.
