Study On Atmospheric Vanadium Contamination In Smelting Area And Performance Of Autotrophic Bioremoval Vanadate

Vanadium smelting activities release a large number of toxic heavy metals(HMs)such as vanadium(V),chromium(Cr),zinc(Zn)and arsenic(As)into atmosphere through high temperature volatilization,which coexist with airborne microbes.However,the distribution of HMs and related microorganisms in ambient aerosols from industrial districts remains largely unknown.Meanwhile,V in atmosphere can infiltrate into the groundwater environment through atmospheric deposition,making it more necessary to study effective remediation technology of V pollution in groundwater.Autotrophic microorganisms can be utilized to remediate the HMs-contaminated groundwater in the presence of inorganic electron donors,without the secondary pollution and aquifer blockage.Firstly,the seasonal dynamics of HMs and microorganisms in the atmospheric aerosol of V smelter in Panzhihua was investigated.Multiple HMs(V,Zn,As,Cr,Cu and Ni)were detected in ambient aerosols samples,in which V was obtained the highest concentration,especially in spring at 228.0±10.3 ng/m~3.The lowest V concentration was monitored in Summer due to the intensive rainfall.The distribution of health risks resembles HMs,and children were more sensitive to HMs than adults.V and As mostly contributed to the total health risk.High-throughput 16S r RNA gene sequencing analysis showed that microorganisms in atmosphere were tolerant to these HMs mentioned above.Acinetobacter,with ability to detoxify V(V),was widely distribution during four seasons.In summer,Bacillus,Geobacter and Thauera strains were appeared which can tolerate HMs environment.Batch experiment was conducted to study the autotrophic reduction of V(V)with natural Fe(?)-bearing minerals(pyrrhotite,siderite,magnetite and pyrite)as the inorganic electron donors.The results showed that microorganisms can fixed V(V)effectively.In stable period,the highest V(V)average removal efficiency of 66.9±0.07%was obtained in siderite group,while57.0±0.10%,58.5±0.03%and 54.4±0.04%were detected in pyrrhotite,magnetite and pyrite group,respectively.The removal efficiency of V(V)was decreased during continuous long periods operation attributed to iron crusting.V(V)was reduced to V(IV),which was insoluble,and Fe(?)was oxidized to Fe(?I).The microbial community structure changed significantly during operation process based on 16S r RNA gene sequencing.V(V)reducing bacteria Bacillus and Fe(?)oxidizing bacteria Anaerolinea were enriched in reactor,and Bacillus was the dominant bacteria in the B-Siderite group with the highest relative abundance of 31.5%.This study revealed the V pollution level of ambient aerosols in V smelting area and health risk to human beings,and the related microbial communities were analyzed.These findings provide helpful information to better understand the distribution of HMs and related microbial communities in aerosol from smelting regions.In addition,natural Fe(?)-bearing can be used as electron donor to autotrophically reduce V(V)in groundwater,which provides profound thinking for in-situ remediation of V(V)contaminated groundwater.