Microbial Remediation Research Of Vanadium-Based Combined Pollution Environment

The vanadium mining and smelting process caused heavy metal vanadium and other heavy metals and organic matter to enter the environment,causing serious composite pollution.The use of domesticated microorganisms to treat combined pollution of pentavalent vanadium(V(V))and other heavy metals and organic matter in groundwater is a promising approach.In the past studies,people have researched more about the single pollution of vanadium in groundwater,while ignoring the impact of composite pollution of vanadium and other heavy metals and organic matter in the groundwater environment.In this study,the V(V)and the simultaneous removal of heavy metals and organic matter were studied by microbial method for vanadium-based composite pollution.Firstly,the feasibility of simultaneous reduction of V(V)and heavy metal hexavalent chromium(Cr(VI))by mixed microorganisms was explored.It was found through experiments that the removal efficiencies of V(V)and Cr(VI)after 72 hours were 97.0 ± 1.0% and 99.1 ± 0.7%,respectively.The experiment reveals the interaction between V(V)and Cr(VI).When they coexist,the biological reduction of Cr(VI)is promoted,and the reduction of V(V)is inhibited.After XPS analysis,the main products of V(V)and Cr(VI)after the reaction were V(IV)and Cr(III),respectively.Microbial community analysis showed that Geobacter can directly or indirectly be responsible for the reduction of V(V)and Cr(VI).Thauera is closely related to the reduction of Cr(VI).Spirochaeta and Spirochaetaceae were functional microorganisms that can be reduced V(V)and Cr(VI)simultaneously.Secondly,the microorganisms are simultaneously used to remove V(V)and pentachlorophenol(PCP).After 7 days,the removal efficiencies of V(V)and PCP were 96.0 ± 1.8% and 43.4 ± 4.6%,respectively.By XPS analysis,the reduction product of V(V)was identified as V(IV),and the intermediate products of PCP reduction were 2,4,6-trichlorophenol,2,4-dichlorophenol,4-chlorophenol and phenol.Pseudomonas is a functional microorganism that bioreductive V(V).Acinetobacter and Comamonas play a role in the removal of PCP.Pseudomonas can simultaneously promote the removal of V(V)and PCP.Finally,the process of simultaneous reduction of V(V)and degradation of phenanthrene(Phe)by microorganisms was explored.The experimental results show that after 24 hours,the removal efficiency of V(V)was 92.0 ± 1.5%,and the removal efficiency of Phe was 73.1 ± 1.2%.The 250 days continuous column experiment revealed the effects of initial pollutant concentration,hydraulic retention time and carbon source concentration.The XPS analysis confirmed that the reduction product of V(V)was V(IV),and the degradation metabolites of Phe were p-cresol,salicylic acid,2,4-di-tert-butylphenol and cyclohexane.Microbial community analysis found that Geobacter and Thiobacillus were functional microorganisms that can both reduce V(V)and degrade Phe.In summary,this study explored the efficient treatment of microorganisms combined with vanadium and heavy metals and organic matter,and provided new research ideas for the composite pollution control of vanadium.