Dynamic experiment on remediation of acid mine drainage by iron-carbon microelectrolysis enhancing sulfate-reducing bacteria

• Published in: Environmental science water research & technology 2023-05, Vol.9 (5), p.1413-1425
• Main Authors: Li, Hanzhe, Di, Junzhen, Dong, Yanrong, Bao, Sihang, Fu, Saiou
• Format: Article
• Language: English
• Subjects: Acid mine drainage; Analytical methods; Bacteria; Biodiversity; Biological activity; Bioreactors; Carbon; Carbonates; Chemical precipitation; Copper; Coprecipitation; Electron microscopy; Energy methods; Flocculation; Flora; Heavy metals; Hydroxides; Ion concentration; Iron; Manganese; Mass ratios; Metal ions; Microorganisms; Mine drainage; Next-generation sequencing; Relative abundance; Remediation; Removal; Scanning electron microscopy; Spectroscopy; Sulfate reduction; Sulfate-reducing bacteria; Sulfates; Sulphate reduction; Sulphides; Systems stability; Water pollution; X-ray diffraction; Zinc
• ISSN: 2053-1400; 2053-1419
• DOI: 10.1039/d2ew00947a

Sulfate-reducing bacteria (SRB) are easily inhibited by heavy metal ions and low pH when treating acid mine drainage (AMD), so iron-carbon microelectrolysis (IC-ME) was used to enhance SRB activity. The remediation AMD dynamic experiments were carried out by constructing seven groups of IC-ME bioreactors with different mass ratios (4 : 1, 3 : 1, 2 : 1, 1 : 1, 1 : 2, 1 : 3, and 1 : 4 of iron to carbon), and the variation of microbial flora under IC-ME enhancement was explored by high-throughput sequencing. The mechanism of IC-ME was revealed by the variation of ion concentration along the path of the reactor and Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD) methods. The results indicated that SRB in the IC-ME bioreactor maintained good biological activity when repairing AMD, with a stable ability of sulfate removal. When the mass ratio of iron to carbon was 3 : 1, the removal efficiency of SO 4 2− was 98.2%, and the removal efficiency of Cu 2+ , Zn 2+ , Mn 2+ , and TFe was all above 99%. SO 4 2− was reduced to S 2− by SRB and precipitated with metal ions; Cu 2+ was mainly replaced by elemental copper deposited on the iron surface; Zn 2+ was mainly removed in the form of sulfide and hydroxide precipitation; Mn 2+ was mainly removed by manganese carbonate precipitation and iron ion coprecipitation; TFe was removed by oxide, hydroxide, and flocculation. Microbial community analysis showed that SRB in the IC-ME bioreactor was not a single genus, and its relative abundance and biodiversity were higher than control groups, with higher system stability. This study confirmed that IC-ME enhancing SRB as a low-energy method for AMD remediation will bring extensive application prospects. This study combined IC-ME technology with SRB to strengthen biological activity and to achieve the simultaneous removal of heavy metal ions and sulfate to provide new methods for realizing low-cost, efficient and stable treatment of AMD.