Antimony (Sb) mining and smelting activities caused Sb and arsenic (As) pollution in the soil, posing a threat to the ecosystem and human health. To remediate Sb and As in co-contaminated soil and realize the resource utilization of typical industrial solid waste, electrolytic manganese residue (EMR)-biochar composite (EB) was prepared from EMR and distillers grains by a facile one-step pyrolysis method. The immobilization effect of EB on Sb and As in soil was studied using a column leaching experiment. Pot and soil incubation experiments were conducted to investigate the effects of EB on the bioavailability of Sb/As and microbial communities. The results showed that 4 wt% EB treatment reduced the accumulated contents of Sb and As in leachates by 29.21%-55.65% and 53.51%-68.95%, respectively, compared with the control. EB treatment (1 wt%) improved plant height, root length, phytomass, and chlorophyll content of Brassica campestris L. Compared to the untreated soils, 4 wt% EB treatment increased the well-crystallized hydrous oxides and residual fractions of Sb and As by 4.29%-6.23% and 4.09%-7.03%, respectively. The concentrations of bioavailable Sb and As in soil were reduced by 48.01%-71.92% and 52.31%-53.81%, respectively. EB interacted with As/Sb-resistant dominant microorganisms such as Proteobacteria in the soil, promoted their growth, and enhanced the immobilization of Sb/As. EB increased the relative abundance of redox-related bacteria of Sb and As (Thiobacillus and Sulfuriferula) by affecting soil EC and bioavailable Sb/As. The immobilization of As and Sb by EB include complexation, hydrogen bonding, and pore filling. These findings provide novel insights into the remediation of Sb and As co-contaminated soils.
Keywords: Antimony; Arsenic; Biochar; Electrolytic manganese residue; Soil remediation.
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