Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China.
Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety and MOE Key Laboratory of Theoretical Chemistry of Environment, School of Environment, South China Normal University, Guangzhou 510006, China.
Water Res. 2024 May 1;254:121423. doi: 10.1016/j.watres.2024.121423. Epub 2024 Mar 5.
Biological sulfidogenic processes based on sulfate-reducing bacteria (SRB) are not suitable for arsenic (As)-containing acid mine drainage (AMD) treatment because of the formation of the mobile thioarsenite during sulfate reduction. In contrast, biological sulfidogenic processes based on sulfur-reducing bacteria (SRB) produce sulfide without pH increase, which could achieve more effective As removal than the SRB-based process. However, the reduction ability and toxicity tolerance of SRB to As remains mysterious, which may substantially affect the practical applicability of this process when treating arsenate (As(V))-containing AMD. Thus, this study aims to develop a biological sulfur reduction process driven by SRB, and explore its long-term performance on As(V) removal and microbial community evolution. Operating under moderately acidic conditions (pH=4.0), the presence of 10 mg/L As(V) significantly suppressed the activity of SRB, leading to the failure of As(V) removal. Surprisingly, a drop in pH to 3.0 enhanced the tolerance of SRB to As toxicity, allowing for efficient sulfide production (396±102 mg S/L) through sulfur reduction. Consequently, effective and stable removal of As(V) (99.9 %) was achieved, even though the sulfidogenic bacteria were exposed to high levels of As(V) (42 mg/L) in long-term trials. Spectral and spectroscopic analysis showed that As-bearing sulfide minerals were present in the bioreactor. Remarkably, the presence of As(V) induced notable changes in the microbial community composition, with Desulfurella and Clostridium identified as predominate sulfur reducers. The qPCR result further revealed an increase in the concentration of functional genes related to As transport (asrA and arsB) in the bioreactor sludge as the pH decreased from 4.0 to 3.0. This suggests the involvement of microorganisms carrying asrA and arsB in an As transport process. Furthermore, metagenomic binning demonstrated that Desulfurella contained essential genes associated with sulfur reduction and As transportation, indicating its genetic potential for sulfide production and As tolerance. In summary, this study underscores the effectiveness of the biological sulfur reduction process driven by SRB in treating As(V)-contaminated AMD. It offers insights into the role of SRB in remediating As contamination and provides valuable knowledge for practical applications.
基于硫酸盐还原菌（SRB）的生物硫化作用过程不适合处理含砷酸性矿山废水（AMD），因为在硫酸盐还原过程中会形成可移动的硫代亚砷酸盐。相比之下，基于硫还原菌（SRB）的生物硫化作用过程在不增加 pH 值的情况下产生硫化物，这可以比基于 SRB 的过程更有效地去除砷。然而，SRB 对砷的还原能力和毒性耐受能力仍然神秘莫测，这可能会极大地影响该过程在处理含砷酸盐（As(V))的 AMD 时的实际适用性。因此，本研究旨在开发一种由 SRB 驱动的生物硫还原过程，并探讨其对 As(V)去除和微生物群落演替的长期性能。在中等酸性条件（pH=4.0）下运行，10mg/L 的 As(V)的存在显著抑制了 SRB 的活性，导致 As(V)去除失败。令人惊讶的是，将 pH 值降低到 3.0 增强了 SRB 对砷毒性的耐受性，从而通过硫还原产生了高效的硫化物（396±102mg S/L）。因此，即使在长期试验中，硫化菌暴露在高浓度的 As(V)（42mg/L）下，也能实现有效的、稳定的 As(V)去除（99.9%）。光谱和光谱分析表明，生物反应器中存在含砷的硫化物矿物。值得注意的是，As(V)的存在导致微生物群落组成发生显著变化，Desulfurella 和 Clostridium 被鉴定为主要的硫还原剂。qPCR 结果进一步表明，随着 pH 值从 4.0 降低到 3.0，生物反应器污泥中与 As 运输（asrA 和 arsB）相关的功能基因的浓度增加。这表明携带 asrA 和 arsB 的微生物参与了 As 运输过程。此外，宏基因组 binning 表明，Desulfurella 含有与硫还原和 As 运输相关的必需基因，表明其在产生硫化物和耐受 As 方面的遗传潜力。总之，本研究强调了由 SRB 驱动的生物硫还原过程在处理含 As(V)的 AMD 方面的有效性。它揭示了 SRB 在修复 As 污染方面的作用，并为实际应用提供了有价值的知识。
