Synergistic Removal of As(III) in Acidic Wastewater

Strategic Insights -

Researchers from the School of Minerals Processing & Bioengineering, Central South University, have developed a novel process for treating acidic wastewater containing As(III). The study utilized Acidithiobacillus ferrooxidans (A. ferrooxidans), pyrite, and red mud to synergistically remove As(III) from wastewater with a pH of 2.0 and an As(III) concentration of 200 mg/L. The results showed that the optimal As(III) removal efficiency was 88.26% when using a 1:1 red mud-to-pyrite ratio with A. ferrooxidans.

Key Takeaways:

  • The mining and metallurgical industry generates acidic wastewater containing As(III), posing a threat to human health.
  • The novel process developed by the researchers uses A. ferrooxidans, pyrite, and red mud to synergistically remove As(III) from wastewater.
  • The optimal As(III) removal efficiency was achieved when using a 1:1 red mud-to-pyrite ratio with A. ferrooxidans.
  • The As(III) removal ratio of red mud and pyrite were only 2.25% and 48.74%, respectively, highlighting the importance of A. ferrooxidans in the process.
  • The oxidation of pyrite by A. ferrooxidans enhanced the synergistic removal of As(III) by red mud and pyrite.
  • The surface renewal of pyrite catalytically generated more •OH, which oxidized As(III) to As(V), making As easier to adsorb by the minerals.
  • The pH was raised to approximately 4.0 by the red mud, and the Fe(III) generated through bacterial oxidation underwent hydrolysis, forming a shell-like structure on the red mud's surface.
  • The Al-O and Fe(III)-O on the red mud surface, as well as Fe(III)-O from the hydrolysis products, primarily contributed to the As(III) and As(V) adsorption.

Statistics:

  • As(III) concentration in wastewater: 200 mg/L
  • Optimal As(III) removal efficiency: 88.26%
  • As(III) removal ratio of red mud: 2.25%
  • As(III) removal ratio of pyrite: 48.74%
  • Increase in pH: approximately 2.0 to 4.0
  • Fe(III) concentration generated through bacterial oxidation: sufficient to form a shell-like structure on the red mud's surface

Sources:

  • Yang, B. et al. Significant Enhancement of Acidithiobacillus Ferrooxidans On the Synergistic Removal of As(Iii) By Pyrite and Red Mud: Migration and Transformation of As and Fe. Chemical Engineering Journal, 2025;519.
  • NewsRx. Investigators at School of Minerals Processing & Bioengineering Report Findings in Acidithiobacillus [Significant Enhancement of Acidithiobacillus Ferrooxidans On the Synergistic Removal of As(Iii) By Pyrite and Red Mud: Migration and ...]. Life Science Weekly. October 21, 2025; p 1911.