玄武岩纤维填料应用于两种混合生长反应器的评价

采用单丝直径微米级的伞状玄武岩纤维(BF)作为填料,将其引入序批式反应器(SBR)和后置缺氧反硝化SBR外聚合物(EPS)含量和扫描电子显微镜形貌图,考察了两种SHBR的污水处理效果。试验结果表明:基于SBR的SHBR的出水COD、氨氮、总氮去除率分别为83.2%、89.9%、86.8%;基于后置缺氧反硝化SBR的SHBR优良,而基于后置缺氧反硝化SBR的SHBR的脱氮效果得到进一步的优化和提升。两种SHBR的BF填料中EPS含量分析结果显示:在好氧环境下,蛋白质(PN)的含量高于多糖(PS)的含量;在缺氧条件下,PS的含量明显高于PN的含量。     

Super-oleophilicity Co-doping Co2+/F-/TiO2 one-dimensional nanotubes for photocatalytic denitrification of light oil

In this study, a simple hydrothermal synthesis method was adapted for the preparation of Co-doping Co²⁺/F^-/TiO₂ nanotubes photocatalyst, and the micro-nano structure of catalysts prepared by biomimetic technology which makes the catalyst have super-oleophilicity property. Co²⁺/F^-/TiO₂ revealed improved photocatalytic performance for denitrification of light oil compared to single TiO₂ photocatalysts. The enhance of photocatalytic activity can be attributed to narrowing the band gap, increasing the light response wavelength and exposing more highly active crystal surfaces due to synergistic effects of Co²⁺ and F^? in the photocatalyst.     

大气状态下AFM阳极氧化加工Si的研究

Si纳米氧化线是构筑基于Si的纳米器件的基础。通过AFM针尖诱导阳极氧化加工的n型Si(100)的实验得到凸出的n型Si(100)氧化物高度和偏置电压成线性关系,与针尖扫描速度成负对数关系,并在前人的基础上深化了AFM针尖诱导氧化加工的机理和理论模型,得到了合适的加工条件为偏压8 V和扫描速度1μm/s。     

Simultaneous sulfide and acetate oxidation under denitrifying conditions using an inverse fluidized bed reactor

BACKGROUND: Simultaneous removal of sulfur, nitrogen and carbon compounds from wastewaters is a commercially important biological process. The objective was to evaluate the influence of the CH₃COO^?/NO₃^? molar ratio on the sulfide oxidation process using an inverse fluidized bed reactor (IFBR). RESULTS: Three molar ratios of CH₃COO^?/NO₃^? (0.85, 0.72 and 0.62) with a constant S^2?/NO₃^? molar ratio of 0.13 were evaluated. At a CH₃COO^?/NO₃^? molar ratio of 0.85, the nitrate, acetate and sulfide removal efficiencies were approximately 100%. The N₂ yield (g N₂ g^?1 NO₃^?‐N consumed) was 0.81. Acetate was mineralized, resulting in a yield of 0.65 g inorganic‐C g^?1 CH₃COO^?‐C consumed. Sulfide was partially oxidized to S⁰, and 71% of the S^2? consumed was recovered as elemental sulfur by a settler installed in the IFBR. At a CH₃COO^?/NO₃^? molar ratio of 0.72, the efficiencies of nitrate, acetate and sulfide consumption were of 100%, with N₂ and inorganic‐C yields of 0.84 and 0.69, respectively. The sulfide was recovered as sulfate instead of S⁰, with a yield of 0.92 g SO₄^2?‐S g^?1 S^2? consumed. CONCLUSIONS: The CH₃COO^?/NO₃^? molar ratio was shown to be an important parameter that can be used to control the fate of sulfide oxidation to either S⁰ or sulfate. In this study, the potential of denitrification for the simultaneous removal of organic matter, sulfide and nitrate from wastewaters was demonstrated, obtaining CO₂, S⁰ and N₂ as the major end products. Copyright © 2008 Society of Chemical Industry     

DO浓度对SUFR系统同步硝化反硝化的影响

采用螺旋升流式反应器（SUFR）处理生活污水，考察了好氧反应池中DO浓度对其同步硝化反硝化的影响。结果表明，在好氧反应池上部溶解氧浓度为3．0～3．5mg／L时，发生了明显的同步硝化反硝化现象，其对TN的去除量占SUFR系统对TN去除总量的16％左右；好氧反应池中的同步硝化反硝化反应只发生在池的下部，其中、上部只进行了好氧硝化反应；SUFR系统中好氧反应池上部的最佳溶解氧浓度范围为3．0～3．5mg／L，此时系统的硝化和反硝化效果最佳，好氧反应池中的脱氮效果也较好，系统对TN的去除率〉84％。     

钕电解阳极过电位的测定

用慢扫描示波法测定了钕电解的阳极过电位 .考察了温度、阳极电流密度、Nd2 O3添加量、电解质组成等因素对阳极过电位的影响 ,探讨了降低阳极过电位的可能途径 .结果表明 ,阳极过电位随阳极电流密度的增加而增大 ,随温度的升高而减小 ,一定范围内 ,阳极过电位与阳极电流密度的对数呈线性关系 ,满足塔菲尔方程 ;电解质中LiF和Nd2 O3浓度增加 ,阳极过电位降低 ;适当控制阳极电流密度、升高温度、增加电解质中LiF和Nd2 O3的浓度并尽可能减小极间距 ,均有利于降低阳极过电位     

环境因素对碳钢点蚀临界电势的影响

采用动电势扫描法测定了不同体系中碳钢发生点蚀的临界电势Eb。结果表明 :当Cl- 浓度 <0 .0 1mol/L时 ,随Cl- 浓度增加 ,临界电势负移并与Cl- 浓度成线性关系 ;pH值在 7～ 11之间 ,随pH值增加 ,临界电势正移并与pH值成线性关系 ;随温度增加 ,临界电势负移并与温度成线性关系。     

Change of characteristics of desulfurization and denitrification by combustion flue gas composition and electrode configuration under pulsed corona discharge

Laboratory-scale and parametric experiments of SO₂ and NO_x removal from the simulated combustion gas by pulsed corona discharge have been performed by changing the combustion gas composition and temperature, the electrode configuration of plasma reactor, and the polarity of high-voltage electrode. The following results are obtained: 1) the higher the concentration of H₂O and O₂, the higher the efficiency of desulfurization and denitrification at the same specific input; 2) the pulsed corona discharge with a voltage pulsewidth as short as 200 ns of negative polarity shows the possibility to attain almost 90 percent deSO_x and deNO_x efficiency at the specific discharge input of 20 J/g, which is almost the same as the specific input in the electron-beam process; 3) the deNO_x characteristics show a little temperature dependence in the range of 70 to 130°C, but the deSO_x efficiency increases rapidly in the temperature region below 100°C suggesting the thermochemical dependence of deSO_x reaction; 4) when desulfurization and denitrification proceed, the white dendritic powder deposits on the plasma reactor whose composition is identified to be 49 mol% (NH₄)₂SO₄ and 47 mol% of 2NH₄NO₃ · (NH₄)₂SO₄, and the ratio of SO₂, NO and NH₃ of the deposit is almost equal to that of supplied gas.     

Inhibition of sulfide on the simultaneous removal of nitrate and p‐cresol by a denitrifying sludge

BACKGROUND: Many industrial discharges, such as those generated from petrochemical refineries, contain large amounts of sulfurous, nitrogenous and organic contaminants. Denitrification has emerged as a suitable technology for the simultaneous removal of these pollutants in a single reactor unit; however, more evidence is demanded to clarify the limitations of denitrification on the simultaneous removal of sulfide and phenolic contaminants and to optimize the biological process. The aim of this study was to evaluate the capacity of a denitrifying sludge to simultaneously convert sulfide and p‐cresol via denitrification. RESULTS: Sulfide was the preferred electron donor over p‐cresol, imposing a 5 h lag phase (required for complete sulfide removal) on organotrophic denitrification. Addition of sulfide (20 mg S^2? L^?1) to p‐cresol‐amended denitrifying cultures also decreased the reduction rate of nitrate and nitrite, as well as the production rate of nitrogen gas. Nitrite reduction rate was the most affected step by sulfide, decreasing from 35 to 21 mg N (g VSS d)^?1. A synergistic inhibitory effect of nitrate and sulfide was also observed on nitrite reduction. Despite the effects of sulfide on the respiratory rates monitored, complete removal of nitrate, sulfide and p‐cresol could be achieved after 48 h of incubation. CONCLUSION: Our results suggest that simultaneous removal of sulfide and p‐cresol could be achieved in denitrifying reactors, but a large hydraulic residence time may be required to sustain an efficient process due to inhibitory effects of sulfide. Copyright © 2008 Society of Chemical Industry     

The relationship between denitrifying bacteria and methanogenic bacteria in a mixed culture system of acclimated sludges

The interaction between denitrification and methanogenesis, with methanol functioning as an electron donor, has been examined through usage of a mixed culture system of denitrifying sludge and methanogenic sludge in an anaerobic bioreactor. Competition for methanol between these two kinds of biocommunity could not be observed, whereas methanogenesis was suppressed as long as nitrate and nitrite were made available in the mixed system. The inhibition of methanogenesis in the methanogenic sludge caused by nitrogen oxides was studied. The redox potential (E_h) of the culture was monitored and/or controlled for the sake of characterizing the behavior of the biocommunities. An addition of nitrite elevated the E_h of the culture less than nitrate did. Nitrite addition, however, exerted a stronger inhibitory effect on methanogenesis as compared to nitrate at the same concentration. The influence of redox potential on the methanation of methanol was examined by using a methanogenic sludge in the E_h-stat batch culture. The hypothesis that the inhibitory effect being expressed by the nitrogen oxides is not simply attributed to an elevation of the redox potential of the culture is supported by the experimental results. The toxic effect of the nitrogen oxides themselves could also have possibly contributed significantly.