天然Fe(Ⅱ)矿物-生物质强化微生物还原固定五价钒研究

Microbial reduction and fixation of pentavalent vanadium enhanced by natural Fe(II) mineral-biomass

摘要:

【目的】重金属钒的环境危害日益受到关注，微生物可实现高毒性的五价钒[pentavalent vanadium, V(V)]的还原固定，其中电子供体是微生物还原V(V)的关键，尽管天然Fe(II)矿物和天然生物质均被报道可单独支持微生物还原V(V)，而基于两者构建的混养体系中微生物还原V(V)的特征尚未揭示。【方法】本研究对天然Fe(II)矿物和生物质进行优选并复配组合，探究混养生物体系中五价钒[V(V)]的还原机理。【结果】磁黄铁矿和木屑对V(V)的去除效率最高，分别为54.2%±3.4%和67.1%±3.1%。当优选的磁黄铁矿与木屑组合复配比例为1:3时可达到最高的V(V)去除效率82.7%±3.1%。V(V)被还原为不溶性V(IV)沉淀，Fe(II)和S(-II)分别被氧化为Fe(III)和SO₄²⁻。在混养体系中，脱硫菌(Desulfurivibrio)和硫菌属(Thiobacillus)等自养菌属可能参与磁黄铁矿的氧化与V(V)还原，并利用无机碳源合成有机中间代谢产物，与无胆甾原体属(Acholeplasma)等纤维素降解菌分解木屑的产物一起，被Bacteroidetes_vadinHA17等异养生物利用还原V(V)。【结论】本研究为地下水V(V)污染提供了一种有前景的修复方法。

Abstract:

[Objective] The environmental hazard of heavy metal vanadium is increasingly concerned. Microorganisms can achieve reductive immobilization of highly toxic pentavalent vanadium (V(V)), while electron donor is the key to this bioprocess. Although both natural Fe(II)-bearing minerals and natural biomass have been reported to independently support microbial V(V) reduction, the characteristics of microbial V(V) reduction under mixotrophic condition based on these two materials have not been revealed yet. [Methods] In this study, natural Fe(II) minerals and biomass were preferentially selected and compounded in combination to investigate the reduction mechanism of V(V) in a mixotrophic biological system. [Results] The results showed that the highest V(V) removal efficiencies of 54.2%±3.4% and 67.1%±3.1% were achieved for pyrrhotite and woodchips, respectively. The highest V(V) removal efficiency of 82.7%±3.1% was achieved when the preferred combination of pyrrhotite and woodchips was compounded at a ratio of 1:3. V(V) was reduced to insoluble V(IV) precipitate, while Fe(II) and S(-II) were oxidized to Fe(III) and SO₄^2-, respectively. In the mixotrophic system, chemolithoautotrophic bacterial genera such as Desulfurivibrio and Thiobacillus might be involved in the oxidation of pyrrhotite coupled to V(V) reduction and the synthesis of organic intermediate metabolites using inorganic carbon sources. Together with the decomposing products of woodchips by cellulose degrading bacteria such as Acholeplasma, these organics were utilized by chemoorganoheterotrophic V(V) reducers such as Bacteroidetes_vadinHA17 to reduce V(V). [Conclusion] This study provides a promising remediation method for groundwater V(V) contamination.