This study presents a novel approach,the Supercapacitor Microbial Electrolysis Cell(SCMEC),which utilizes a supercapacitor as an external power source to enhance the efficiency of autotrophic nitrogen removal in low C...This study presents a novel approach,the Supercapacitor Microbial Electrolysis Cell(SCMEC),which utilizes a supercapacitor as an external power source to enhance the efficiency of autotrophic nitrogen removal in low C/N ratio wastewater.The results demonstrated that the SC-MEC system,operating under anaerobic conditions and devoid of any organic carbon source,exhibited exceptional performance in ammonia oxidation and total nitrogen(TN)removal when solely relying on ammonia nitrogen as the electron donor.Operating at a voltage of 1.8 V with a capacitance capacity of 30 F,ammonium oxidation rated up to 56.51 mg/L/day and TN removal rated up to 54.64 mg/L/day,in which 97%of ammonium nitrogen was converted to gaseous nitrogen.Furthermore,the charging and discharging process of supercapacitors autonomously regulated the bipolar potentials.Cyclic voltammetry(CV)analysis showed the significantly enhanced electrochemical activity of the SCMEC system during the reaction process.Based on in-situ CV test results,itwas inferred that this enhancementwas associated with extracellular electron transfer mediators.Themicrobial community analysis revealed a process of synchronous nitrification and denitrification(SND)coupled with anammox,involvingmultiple genera,such as Candidatus Kuenenia,Nitrosomonas,Truepera,and Bosea.In conclusion,this study highlights the tremendous potential of SC-MEC in achieving efficient autotrophic nitrogen removal,offering more feasible and economical solutions for addressing low C/N water pollution issues.展开更多
External organic carbon sources are needed to provide electron donors for the denitrification of wastewater with a low COD/NO_(3)^(-)-N(C/N)ratio,increasing the treatment cost.The economic strategy is to enhance the b...External organic carbon sources are needed to provide electron donors for the denitrification of wastewater with a low COD/NO_(3)^(-)-N(C/N)ratio,increasing the treatment cost.The economic strategy is to enhance the bioactivity and/or biodiversity of denitrifiers to efficiently utilize organic substances in wastewater.In this study,novel zero-valent iron(ZVI)composite carriers were prepared and implemented in a suspended carrier biofilm reactor to enhance the bioactivity and/or biodiversity of denitrifiers.At the influent C/N ratio of 4(COD was 179.5±5.0 mg/L and TN was 44.2±0.8 mg/L),COD and TN removal efficiencies were 85.1%and 66.4%,respectively,in the reactors filled with 3 wt%ZVI composite carriers.In contrast,COD and TN removal efficiencies were 70.4%and 55.3%,respectively,in the reactor filled with conventional high-density polyethylene(HDPE)biofilm carriers.The biofilm formation on the 3 wt%ZVI composite carriers was optimized due to its higher roughness(surface square roughness increased from 76.0 nm to 93.8 nm)and favorable hydrophilicity(water contact angle dropped to 72.5°±1.4°from 94.3°±3.2°)compared with the HDPE biofilm carriers.In addition,heterotrophic denitrifiers,Thauera and Dechloromonas,were enriched,whereas autotrophic denitrifiers,Raoultella and Thiobacillus,exhibited high relative abundance in the biofilm of ZVI composite carriers.The coexistence of heterotrophic denitrifiers and autotrophic denitrifiers on the surface of ZVI composite carriers provided mixotrophic metabolism of denitrification(including heterotrophic and iron-based autotrophic),thereby ensuring effective denitrification for wastewater with a low C/N ratio without external organic carbon source addition.展开更多
The Ti（C,N）precipitation and texture evolution in ultra-low carbon Ti-bearing enamel steel were studied to discover their correlation.Two different cooling paths of simulative coiling were adopted to gain different ...The Ti（C,N）precipitation and texture evolution in ultra-low carbon Ti-bearing enamel steel were studied to discover their correlation.Two different cooling paths of simulative coiling were adopted to gain different morphologies of Ti（C,N）precipitate in hot strips.It is found that the Ti（C,N）precipitate in hot strip using Path 2（put into asbestos box and air cooled）are finer and much more in quantity than that in hot strip using Path 1（held at 730℃ for 30min and furnace cooled）.The morphology of Ti（C,N）precipitate in hot strip has great effect on recrystallization texture in the subsequent cold-rolled annealed sheet.γ-fiber texture of strong recrystallization is gained in coldrolled and annealed sheet came from Path 1.On the contrary,in the one came from Path 2,theγ-fiber texture is weak.This may be due to the pinning force of numerous fine Ti（C,N）precipitate which retard the growth of preferential nucleated{111}orientated grains.Annealed steel sheets in the test came from both paths have excellent fishscale resistance.展开更多
为提升微生物电化学系统(Microbial Electrochemical System,MES)处理低碳氮比(C/N)废水的反硝化效能,采用水热合成法制备二氧化锰(MnO_(2))修饰碳布电极,运用周期极性反转策略(阳极+0.2 V/阴极-0.5 V vs SCE)培养双向电子传递生物膜,...为提升微生物电化学系统(Microbial Electrochemical System,MES)处理低碳氮比(C/N)废水的反硝化效能,采用水热合成法制备二氧化锰(MnO_(2))修饰碳布电极,运用周期极性反转策略(阳极+0.2 V/阴极-0.5 V vs SCE)培养双向电子传递生物膜,以提高界面电子交换能力。结果表明:MnO_(2)修饰组阴极期起始电流密度达-10.2 A/m^(2),生物膜阳极期最大储电子量为(0.80±0.03)mmol,较对照组(无修饰空白碳布)提升15.9%;修饰组总氮去除率从初始36%提升至91%,且全程无亚硝酸盐积累。MnO_(2)修饰实现了功能菌的选择性富集,核心电活性菌Geobacter sp.相对丰度从50.84%提升至70.21%,群落功能专一性显著提高。氮代谢功能基因分析显示,反硝化全通路基因相对拷贝数同步提升2.17倍,激活了硝酸盐→亚硝酸盐→一氧化氮→一氧化二氮→氮气的反硝化通路。电化学测试发现,MnO_(2)修饰组在2.0 mV/s的扫描速率下,氧化态峰电流中直接电子传递贡献率达56%,显著高于对照组,电极与生物膜间的电子交换速率明显提升。生物膜三维结构分析发现,修饰组活菌向生物膜表层迁移,硝酸盐扩散距离缩短,胞外聚合物形成均匀的三维网络骨架,多糖与蛋白组分分布均衡,生物膜结构稳定性与传质效率得到了显著优化。展开更多
The effect of Ti （ C, N） on properties of low-carbon MgO - C bricks was investigated. The phase composition and the microstructure of the matrix of low-carbon MgO - C brick containing Ti （ C, N） were studied by XR...The effect of Ti （ C, N） on properties of low-carbon MgO - C bricks was investigated. The phase composition and the microstructure of the matrix of low-carbon MgO - C brick containing Ti （ C, N） were studied by XRD and SEM analysis together with EDS. The results showed that Ti （ C, N） distributed in the matrix of lowcarbon MgO - C brick uniformly after being treated at 1 600 ~C for 3 h in coke powder bed, and Ti （C, N） and MgO formed a solid solution. After the treatment at 1 600 ℃ for 3 h in coke powder bed, the bulk density and cold crushing strength of low-carbon MgO - C brick with Ti （ C, N） decreased, and the apparent porosity and linear change rate of specimens increased. The oxidation resistance of low-carbon MgO - C brick with Ti（ C, N） was superior to that of low-carbon MgO - C brick with no additives, but inferior to that of low-car- bon MgO - C brick with Al powder. The slag resistance of the specimen with Ti （ C, N） was excellent as well.展开更多
基金supported by the National Natural Science Foundation of China(No.31970106).
文摘This study presents a novel approach,the Supercapacitor Microbial Electrolysis Cell(SCMEC),which utilizes a supercapacitor as an external power source to enhance the efficiency of autotrophic nitrogen removal in low C/N ratio wastewater.The results demonstrated that the SC-MEC system,operating under anaerobic conditions and devoid of any organic carbon source,exhibited exceptional performance in ammonia oxidation and total nitrogen(TN)removal when solely relying on ammonia nitrogen as the electron donor.Operating at a voltage of 1.8 V with a capacitance capacity of 30 F,ammonium oxidation rated up to 56.51 mg/L/day and TN removal rated up to 54.64 mg/L/day,in which 97%of ammonium nitrogen was converted to gaseous nitrogen.Furthermore,the charging and discharging process of supercapacitors autonomously regulated the bipolar potentials.Cyclic voltammetry(CV)analysis showed the significantly enhanced electrochemical activity of the SCMEC system during the reaction process.Based on in-situ CV test results,itwas inferred that this enhancementwas associated with extracellular electron transfer mediators.Themicrobial community analysis revealed a process of synchronous nitrification and denitrification(SND)coupled with anammox,involvingmultiple genera,such as Candidatus Kuenenia,Nitrosomonas,Truepera,and Bosea.In conclusion,this study highlights the tremendous potential of SC-MEC in achieving efficient autotrophic nitrogen removal,offering more feasible and economical solutions for addressing low C/N water pollution issues.
基金supported by National Science and Technology Major Project Water:Pollution Control and Treatment(No.2012ZX07202006)。
文摘External organic carbon sources are needed to provide electron donors for the denitrification of wastewater with a low COD/NO_(3)^(-)-N(C/N)ratio,increasing the treatment cost.The economic strategy is to enhance the bioactivity and/or biodiversity of denitrifiers to efficiently utilize organic substances in wastewater.In this study,novel zero-valent iron(ZVI)composite carriers were prepared and implemented in a suspended carrier biofilm reactor to enhance the bioactivity and/or biodiversity of denitrifiers.At the influent C/N ratio of 4(COD was 179.5±5.0 mg/L and TN was 44.2±0.8 mg/L),COD and TN removal efficiencies were 85.1%and 66.4%,respectively,in the reactors filled with 3 wt%ZVI composite carriers.In contrast,COD and TN removal efficiencies were 70.4%and 55.3%,respectively,in the reactor filled with conventional high-density polyethylene(HDPE)biofilm carriers.The biofilm formation on the 3 wt%ZVI composite carriers was optimized due to its higher roughness(surface square roughness increased from 76.0 nm to 93.8 nm)and favorable hydrophilicity(water contact angle dropped to 72.5°±1.4°from 94.3°±3.2°)compared with the HDPE biofilm carriers.In addition,heterotrophic denitrifiers,Thauera and Dechloromonas,were enriched,whereas autotrophic denitrifiers,Raoultella and Thiobacillus,exhibited high relative abundance in the biofilm of ZVI composite carriers.The coexistence of heterotrophic denitrifiers and autotrophic denitrifiers on the surface of ZVI composite carriers provided mixotrophic metabolism of denitrification(including heterotrophic and iron-based autotrophic),thereby ensuring effective denitrification for wastewater with a low C/N ratio without external organic carbon source addition.
基金Sponsored by National Natural Science Foundation of China(50527402)National Basic Research Program(973Program)of China(2011CB606306-2)
文摘The Ti（C,N）precipitation and texture evolution in ultra-low carbon Ti-bearing enamel steel were studied to discover their correlation.Two different cooling paths of simulative coiling were adopted to gain different morphologies of Ti（C,N）precipitate in hot strips.It is found that the Ti（C,N）precipitate in hot strip using Path 2（put into asbestos box and air cooled）are finer and much more in quantity than that in hot strip using Path 1（held at 730℃ for 30min and furnace cooled）.The morphology of Ti（C,N）precipitate in hot strip has great effect on recrystallization texture in the subsequent cold-rolled annealed sheet.γ-fiber texture of strong recrystallization is gained in coldrolled and annealed sheet came from Path 1.On the contrary,in the one came from Path 2,theγ-fiber texture is weak.This may be due to the pinning force of numerous fine Ti（C,N）precipitate which retard the growth of preferential nucleated{111}orientated grains.Annealed steel sheets in the test came from both paths have excellent fishscale resistance.
文摘为提升微生物电化学系统(Microbial Electrochemical System,MES)处理低碳氮比(C/N)废水的反硝化效能,采用水热合成法制备二氧化锰(MnO_(2))修饰碳布电极,运用周期极性反转策略(阳极+0.2 V/阴极-0.5 V vs SCE)培养双向电子传递生物膜,以提高界面电子交换能力。结果表明:MnO_(2)修饰组阴极期起始电流密度达-10.2 A/m^(2),生物膜阳极期最大储电子量为(0.80±0.03)mmol,较对照组(无修饰空白碳布)提升15.9%;修饰组总氮去除率从初始36%提升至91%,且全程无亚硝酸盐积累。MnO_(2)修饰实现了功能菌的选择性富集,核心电活性菌Geobacter sp.相对丰度从50.84%提升至70.21%,群落功能专一性显著提高。氮代谢功能基因分析显示,反硝化全通路基因相对拷贝数同步提升2.17倍,激活了硝酸盐→亚硝酸盐→一氧化氮→一氧化二氮→氮气的反硝化通路。电化学测试发现,MnO_(2)修饰组在2.0 mV/s的扫描速率下,氧化态峰电流中直接电子传递贡献率达56%,显著高于对照组,电极与生物膜间的电子交换速率明显提升。生物膜三维结构分析发现,修饰组活菌向生物膜表层迁移,硝酸盐扩散距离缩短,胞外聚合物形成均匀的三维网络骨架,多糖与蛋白组分分布均衡,生物膜结构稳定性与传质效率得到了显著优化。
文摘The effect of Ti （ C, N） on properties of low-carbon MgO - C bricks was investigated. The phase composition and the microstructure of the matrix of low-carbon MgO - C brick containing Ti （ C, N） were studied by XRD and SEM analysis together with EDS. The results showed that Ti （ C, N） distributed in the matrix of lowcarbon MgO - C brick uniformly after being treated at 1 600 ~C for 3 h in coke powder bed, and Ti （C, N） and MgO formed a solid solution. After the treatment at 1 600 ℃ for 3 h in coke powder bed, the bulk density and cold crushing strength of low-carbon MgO - C brick with Ti （ C, N） decreased, and the apparent porosity and linear change rate of specimens increased. The oxidation resistance of low-carbon MgO - C brick with Ti（ C, N） was superior to that of low-carbon MgO - C brick with no additives, but inferior to that of low-car- bon MgO - C brick with Al powder. The slag resistance of the specimen with Ti （ C, N） was excellent as well.
