In nature selenate reduction and nitrate denitrification both folow a similar biogeochemical mechanism. It has been proved that abiotic stresses such as alternative drying and wetting can exert an important influence ...In nature selenate reduction and nitrate denitrification both folow a similar biogeochemical mechanism. It has been proved that abiotic stresses such as alternative drying and wetting can exert an important influence on nitrate denitrification as well as on selenate reduction. Our experimental results lend great support to the above conclusion.展开更多
Selenium (Se)-containing industrial wastewater is often coupled with notable salinity. However, limited studies have examined biological treatment of Se-containing wastewater under high salinity conditions. In this st...Selenium (Se)-containing industrial wastewater is often coupled with notable salinity. However, limited studies have examined biological treatment of Se-containing wastewater under high salinity conditions. In this study, a sequencing batch reactor (SBR) inoculated with activated sludge was applied to treat selenate in synthetic saline wastewater (3% w/v NaCl) supplemented with lactate as the carbon source. Start-up of the SBR was performed with addition of 1–5 mM of selenate under oxygen-limiting conditions, which succeeded in removing more than 99% of the soluble Se. Then, the treatment of 1 mM Se with cycle duration of 3 days was carried out under alternating anoxic/oxic conditions by adding aeration period after oxygen-limiting period. Although the SBR maintained soluble Se removal of above 97%, considerable amount of solid Se remained in the effluent as suspended solids and total Se removal fluctuated between about 40 and 80%. Surprisingly, the mass balance calculation found a considerable decrease of Se accumulated in the SBR when the aeration period was prolonged to 7 h, indicating very efficient Se biovolatilization. Furthermore, microbial community analysis suggested that various Se-reducing bacteria coordinately contributed to the removal of Se in the SBR and main contributors varied depending on the operational conditions. This study will offer implications for practical biological treatment of selenium in saline wastewater.展开更多
Photocathode with superior catalytic activity,long-term stability,and fast mass/electron transfer is highly desirable but challenging for dye-sensitized solar cell(DSC).Herein,the ZIF-67 grown on carbon cloth is succe...Photocathode with superior catalytic activity,long-term stability,and fast mass/electron transfer is highly desirable but challenging for dye-sensitized solar cell(DSC).Herein,the ZIF-67 grown on carbon cloth is successfully transformed into CoSe2 embedded in N-doped carb on nano cage(CoSe2/N-C)via a growth-carbonization-selenization process.The carb on cloth supported CoSe2/N-C,as photocathode of DSC,demonstrates a good long-term stability and high photovoltaic efficiency(8.40%),outperforming Pt.The good efficiency can be attributed to the high catalytic activity of CoSe2,fast mass tran sfer of porous three-dimensi on al(3D)structure,and good electr on transport derived from the intimate con tact between CoSe2 and highly conductive carb on cloth.The high stability would be ascribed to N-doped carbon coating that perfectly prevents CoSe2 from decomposition.This work will pave the way to develop highly efficient and stable Pt-free photocathode for DSC.展开更多
文摘In nature selenate reduction and nitrate denitrification both folow a similar biogeochemical mechanism. It has been proved that abiotic stresses such as alternative drying and wetting can exert an important influence on nitrate denitrification as well as on selenate reduction. Our experimental results lend great support to the above conclusion.
文摘Selenium (Se)-containing industrial wastewater is often coupled with notable salinity. However, limited studies have examined biological treatment of Se-containing wastewater under high salinity conditions. In this study, a sequencing batch reactor (SBR) inoculated with activated sludge was applied to treat selenate in synthetic saline wastewater (3% w/v NaCl) supplemented with lactate as the carbon source. Start-up of the SBR was performed with addition of 1–5 mM of selenate under oxygen-limiting conditions, which succeeded in removing more than 99% of the soluble Se. Then, the treatment of 1 mM Se with cycle duration of 3 days was carried out under alternating anoxic/oxic conditions by adding aeration period after oxygen-limiting period. Although the SBR maintained soluble Se removal of above 97%, considerable amount of solid Se remained in the effluent as suspended solids and total Se removal fluctuated between about 40 and 80%. Surprisingly, the mass balance calculation found a considerable decrease of Se accumulated in the SBR when the aeration period was prolonged to 7 h, indicating very efficient Se biovolatilization. Furthermore, microbial community analysis suggested that various Se-reducing bacteria coordinately contributed to the removal of Se in the SBR and main contributors varied depending on the operational conditions. This study will offer implications for practical biological treatment of selenium in saline wastewater.
基金the National Natural Science Foundation of China(Nos.21725501,21771019,21475007 and 21675009)the Fundamental Research Funds for the Central Universities(Nos.buctrc201706,buctrc201815 and buctrc201812).
文摘Photocathode with superior catalytic activity,long-term stability,and fast mass/electron transfer is highly desirable but challenging for dye-sensitized solar cell(DSC).Herein,the ZIF-67 grown on carbon cloth is successfully transformed into CoSe2 embedded in N-doped carb on nano cage(CoSe2/N-C)via a growth-carbonization-selenization process.The carb on cloth supported CoSe2/N-C,as photocathode of DSC,demonstrates a good long-term stability and high photovoltaic efficiency(8.40%),outperforming Pt.The good efficiency can be attributed to the high catalytic activity of CoSe2,fast mass tran sfer of porous three-dimensi on al(3D)structure,and good electr on transport derived from the intimate con tact between CoSe2 and highly conductive carb on cloth.The high stability would be ascribed to N-doped carbon coating that perfectly prevents CoSe2 from decomposition.This work will pave the way to develop highly efficient and stable Pt-free photocathode for DSC.
