No abstract

No abstract

In view of the high content of Cu²⁺ and Zn²⁺ in acid mine drainage (AMD), the adsorption properties of lignite for Cu²⁺ and Zn²⁺ were studied. The adsorption performance of lignite for Cu²⁺ and Zn²⁺ was revealed by combining with FT-IR, XPS and EDS. The results showed that the adsorption kinetic model of lignite for Cu²⁺ and Zn²⁺ conformed to the quasi-first-order kinetic model. The isothermal adsorption line fitting models of lignite for Cu²⁺ and Zn²⁺ were in accordance with the Langmuir model and the Freundlich model, respectively. The maximum equilibrium adsorption capacities of lignite for Cu and Zn were 67.84 mg/g and 55.5 mg/g. The adsorption process of Cu²⁺ and Zn²⁺ by lignite involved electrostatic, coordination and ion exchange. Under the condition of coexistence of two kinds of ion, the adsorption site of lignite had stronger binding ability to copper ions.

No abstract

Sulfate-reducing bacteria (SRB) are easily inhibited by heavy metal ions and low pH when treating 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, 1:4), and the variation of microbial flora under IC-ME enhancement was explored by high-throughput sequencing. The mechanism of IC-ME enhanced SRB reactor to repair AMD was revealed by ion concentration change along the reactor, SEM, EDS, XRD, and other methods. The results indicate that SRB in the IC-ME bioreactor maintain a good biological activity when repairing AMD, and had a stable ability of sulfate removal. When the mass ratio of iron to carbon is 3:1, the removal rate of SO4 2-is 98.2%, and the removal rates of Cu2+ , Zn2+ , Mn2+ , and TFe were all above 99 %. The effluent was clear and the substrate utilization was less, which was better than that of other reactors. SO4 2-was reduced to S 2-by SRB and precipitated with metal ions; Cu2+ was mainly replaced by elemental copper deposited on the iron surface; Zn2+ was mainly removed in the form of sulfide and hydroxide precipitation; Mn2+ was mainly removed by manganese carbonate precipitation and iron ion coprecipitation; TFe was removed by oxide, hydroxide, and flocculation. Biocommunity analysis showed that SRB in the IC-ME bioreactor was not a single genus, and its relative abundance was better than control groups, with higher system stability. This study confirmed that the IC-ME enhanced SRB as a low-energy method for AMD will bring extensive application prospects.