双酚A胁迫下5种湿地植物有关抗性酶特征及富集能力研究

以5种适宜北方生长且耐污去污能力较强的湿地植物为材料,研究湿地植物对双酚A(BPA)的耐受机制及富集能力。结果表明,在低含量胁迫范围内(BPA添加质量分数低于63μg/g),叶绿素含量较高的植物是芦苇、再力花和香蒲,总叶绿素的质量分数在1.15 mg/g以上;过氧化物酶活性较强的有香蒲、芦苇,过氧化物酶活性在0.253kat/(g·min)以上;脱氢酶活性相对较强的植物包括香蒲、再力花和菖蒲,脱氢酶活性在17.97μg/g以上;基质脲酶活性相对较强的植物包括芦竹、再力花和菖蒲,脲酶活性在0.66 mg/g以上;基质磷酸酶活性较强的包括香蒲、芦苇,磷酸酶活性在0.25 mg/g以上;对BPA的富集转运能力较强的植物为芦苇、再力花,其中芦苇为BPA低含量下的超累积植物。芦苇、再力花、香蒲为适宜处理含双酚A废水的湿地植物。     

水平潜流人工湿地沿程脱氮效率

为探讨不同水生植物砾石水平潜流人工湿地的沿程脱氮效率,选择了花叶芦竹、旱伞草、再力花、香蒲、芦苇5种挺水植物,均匀种植于长13 m、宽4.5 m的砾石水平潜流湿地,测定了不同植物湿地系统对低污染水的沿程脱氮效率。结果表明,处理两种浓度(总氮10 mg/L和20 mg/L)低污染水时,总氮和氨氮的去除率表现为芦苇>再力花、旱伞草>香蒲>花叶芦竹>未种植,硝态氮和亚硝态氮的去除率表现为花叶芦竹、香蒲、芦苇>再力花>旱伞草、未种植。处理总氮10 mg/L的低污染水时,未种植、花叶芦竹、芦苇、再力花和香蒲湿地对总氮、氨氮、硝态氮和亚硝态氮沿程去除率总体呈下降趋势,尤其是芦苇湿地在1/3段即达到了77.95%的去除效率;砾石填料潜流湿地中芦苇、香蒲的种植长度5 m左右为宜,花叶芦竹、旱伞草、再力花的种植长度9 m左右为宜。处理总氮20 mg/L的低污水时,不同植物湿地系统的总氮、氨氮、硝态氮和亚硝态氮沿程去除率基本呈现前端去除效率高,中部略有降低,后部又有所上升;芦苇、香蒲、旱伞草和再力花至少种植13 m以上,可使湿地出水达到一级A标准,芦苇为最佳选择。因此,应根据不同污染负荷下挺水植物的生长和沿程脱氮效率来设置砾石填料湿地床的规模。     

潜流人工湿地对农村生活污水氮去除的研究

作者研究了潜流水平人工湿地处理农村生活污水中氮的去除效果，结果表明湿地进水TN负荷与出水TN负荷去除之间有较好的线性关系，随着水力停留时间的延长TN去除率也升高，停留时间为4d时，芦苇湿地和菖蒲湿地的脱氮效率可以达到60％以上。从脱氮效果看，芦苇湿地的略好于菖蒲湿地的，有植物系统明显好于无植物系统。在进水NO2^--N浓度小于0．062mg／L、NO3^--N浓度小于1．982mg／L的情况下，无论是连续运行还是间歇运行，大多数情况下，出水浓度都分别低于0．631mg／L和1．00mg／L，两者一般不会有较大的积累。试验分析了湿地脱氮的途径，微生物硝化／反硝化是人工湿地脱氮的主要途径，植物吸收、存储仅占湿地总氮去除量的10％左右，但是植物的存在间接地影响湿地脱氮的其它途径，对提高湿地氮去除率具有重要作用。     

云浮硫铁矿企业集团公司尾矿库废水中试研究

采用污泥回流工艺对云浮硫铁矿尾矿库废水进行中试研究。结果表明,当用石灰控制废水的pH为10,PAC投加量为200μg/g,PAM的投加量为4μg/g,平流沉淀池的表面负荷为0.8m3/m2h时,出水的各项指标都满足广东省地方排放标准《水污染物排放限值》(DB44/26-2001)第二时段一级标准。同时采用污泥回流工艺处理云浮硫铁矿尾矿库废水可使底泥浓度达到5%,节省石灰用量,优于传统的中和处理工艺。     

盐湖水铀新型复合吸附材料制备及吸附性能研究

制备一种新型植物有机复合铀吸附剂。用磷酸三丁酯对樟树叶进行改性,得到一种能有效吸附铀的植物有机吸附剂,通过ICP-MS对铀吸附和解吸实验后溶液进行检测得出吸附效率。结果表明,吸附剂用量为0.02 g,溶液pH 8.5,吸附时间为1 h,初始浓度为200μg/L纯溶液的吸附效率可达98.05%。在实验条件不变的条件下,在模拟盐湖水溶液中,吸附时间为12 h,再用0.25 mol/L HNO_3解吸12 h,用ICP-MS检测吸附后及解吸后溶液的浓度,当溶液矿化度分别为400,200,100 g/L时,铀的提取率分别为74.25%,82.68%,93.53%。该吸附材料制备简单,成本低廉,在碱性、共存离子等复杂条件下可以有效提取盐湖水中铀,为铀提取提供了一种新方法。     

表面流人工湿地对高含量有机污染河水的去除效果研究

利用不同植物(芦苇、香蒲)表流人工湿地处理高含量有机污染河水的研究。结果表明,当水力负荷为0.041m3/(d.m2),进水COD和BOD5分别为178.9～480.2 mg/L和40.75～225.6 mg/L,最大去除效果分别可达到93.64%和99.25%。出水COD低于90 mg/L,BOD5低于22 mg/L,均达到GB 18918-2002排放二级标准。高含量有机污水进入表面流人工湿地之后,有机物有效去除长度为32 m,其中发挥主要作用的场所是距进水点21 m以内的区域。表面流人工湿地中,芦苇床和香蒲床对高含量有机污染物去除效果无明显差异,它们根际和根区细菌总数差别不大。     

低浓度含铀废水处理技术的研究进展

各种人为因素使得环境中的铀及其化合物越来越多,对水体造成了放射性污染。在分析环境中低浓度铀来源的基础上,介绍了对低浓度铀污染水体进行处理的最新技术,并着重探讨了应用植物修复技术处理铀污染的研究现状与发展趋势。     

反渗透浓水的处理工程实例

针对煤化工污水回用处理后产生的反渗透浓水以及脱盐水站产生的反渗透浓水,采用异相催化氧化-微错流絮凝沉淀-生物膜-流砂过滤工艺处理。工程实践表明,处理后出水CODCr的质量浓度低于50 mg/L,NH3-N的质量浓度低于12 mg/L,TN的质量浓度低于20 mg/L,出水水质可达到DB 61/224—2011《黄河流域(陕西段)污水综合排放标准》一级排放标准的要求。介绍了该处理工艺的特点、主要处理构筑物和设备的设计。     

铁炭微电解与硫酸盐还原菌耦合修复铀尾矿库渗滤水的研究

设计了铁炭微电解-硫酸盐还原菌(Fe/C-SRB)、铝炭微电解-硫酸盐还原菌(Al/C-SRB)、炭-硫酸盐还原菌(C-SRB)、铁炭微电解(Fe/C)、铝炭微电解(Al/C)和炭(C)6个反应器,并研究了它们修复铀尾矿库渗滤水中U、Mn、Zn、SO₄^2-以及NO₃^-的效果。结果显示：经过2.5 h,Fe/C-SRB系统出水U浓度降至0.05 mg/L以下;1 d后,Mn浓度降至10 mg/L以下;1 d后,Zn浓度降至0.05 mg/L以下;10 d后,SO₄^2-浓度降至50 mg/L以下;18 d后,NO₃^-浓度降至10 mg/L以下,均达到了相关国家排放标准,并运行稳定,处理效率显著高于其他反应器。60 d时,Fe/C-SRB系统填料中具有还原U(Ⅵ)功能的微生物Desulfotomaculum、Desulfovibrio和Desulfosporosinus群落丰度总和达到61.45%,与Al/C-SRB、...     

不同植物对五氯酚生物富集能力的研究

在添加2 000μg/kg五氯酚的土壤中种植芦苇(Phragmites communis(L.)Trin)、香蒲(Typh orientalis Presl)和水葱(Scirpus tabemaemontani Gmel),探讨不司植物对土壤中五氯酚的富集作用.植物和土壤样品以石油醚振荡提取90min,浓硫酸净化和碳酸...     

吸附水体中铀的研究进展

对吸附处理含铀废水的最新研究进展做了综述,详细介绍了各类吸附材料最新研究成果。     

Recovery of uranium by tannin immobilized on agarose

Tannin, which is a ubiquitous and inexpensive material, was immobilized on agarose gel to produce an excellent adsorbent for uranium recovery from seawater. Optimal conditions for the immobilization of tannin on agarose gel by both the epichlorohydrin and cyanuric chloride coupling procedures were examined in detail. The resulting immobilized tannin has a highly selective ability to adsorb uranium and applicability in both column and batch systems. This adsorbent can recover uranium from natural seawater with high efficiency. The maximum adsorption capacities were 1850 μg uranium g^?1 adsorbent for the tannin immobilized on agarose gel by the epichlorohydrin coupling procedure and 1062 μg g^?1 adsorbent for that produced by the cyanuric chloride coupling procedure.     

Removal and recovery of uranium by modified Pinus radiata D. Don bark

Bark from Pinus radiata D. Don was treated with both sulfuric acid/formaldehyde and nitric acid/formaldehyde. The ability to adsorb uranium by the bark was improved by these treatments, with essentially zero bleed colour into solution. The resin produced by nitric acid/formaldehyde treatment showed, in general, a better retention capacity than that of sulfuric acid/formaldehyde treatment. The nitric acid/formaldehyde modified bark showed 96 % of adsorption of uranium after 1 h and 63 % of desorption from the loaded resin after 3 h in 0.5 M sulfuric acid solution. Unmodified bark and some bark components were also analyzed. Bark was shown to be an excellent adsorber, comparable in efficiency, but costing less than the commercial adsorbing agents.     

Hydrothermal synthesis of silicon oxide clad uranium oxide nanowires

A facile method to synthesize silicon oxide clad uranium oxide nanowires is presented. U₃Si₂, used as a precursor, was oxidized to produce uranium oxide nanocrystallites and amorphous silicon oxide under hydrothermal conditions at 300°C and a pressure of 7.8 × 10⁶ Pa. The growth of uranium oxide nanowires was assisted by silicon oxide via assembling the uranium oxide nanocrystallites in an amorphous silicon oxide matrix. The microstructure and composition of silicon oxide clad uranium oxide nanowires were characterized by XRD, SEM, TEM, and EDS. The uranium oxide in the nanowires was determined as UO_2.34 with a fluoride cubic structure.     

Enzymatically-mediated uranium accumulation and uranium recovery using a Citrobacter sp. Immobilised as a biofilm within a plug-flow reactor

Biofilm-immobilised Citrobacter sp. removed uranyl ion from flows supplemented with glycerol 2-phosphate. The metal uptake mechanism was mediated by the activity of a cell-surface bound phosphatase that precipitated liberated inorganic phosphate with uranyl ion as HUO₂PO₄·4H₂O at the bacterial surface. A modified integrated form of the Michaelis–Menten equation is proposed to describe the removal of metal ion by a columnar bioreactor, where the efficiency of metal removal is semi-quantitatively related to the input flow rate, the total enzyme loading (E₀) and the bioreactor activity. With biofilm-immobilised bacteria, E₀ was further divisible (split) into subparameters of phosphatase titre per bacterium and total biomass surface area. Varying the split E₀ and the reaction temperature modified the bioreactor performance. The immobilised bacteria retained high metal loads without loss in steady-state activity. Accumulated metal was recovered as a concentrated solution.     

吸附法海水提铀材料研究进展

吸附法是海水提铀的最适宜方法之一,选择性好且吸附效率高的吸附材料是从海水中提取铀的最佳材料。本文回顾了到目前为止吸附法海水提铀的无机、有机、无机/有机杂化材料的制备方法、结构、吸附性能和铀吸附机理,介绍了不同海水提铀装置的结构和吸附性能。由于有机/无机杂化材料具有高机械强度、高铀吸附量、低共存离子干扰等优点,是一种理想的海水提铀材料;而且膜式吸附装置由于操作流程简单、可连续化等优点,是一种较佳的吸附方式。开展高铀吸附量、高选择性的吸附剂和处理量大的吸附方式是今后吸附法海水提铀的重要研究方向。     

Structural and spectroscopic investigations on the crystallization of uranium brannerite phases in glass

Brannerite‐based glass‐ceramics with relatively high actinide waste loadings are potential waste forms for the immobilization of actinide‐rich radioactive wastes containing process chemicals. In this work, the crystallization of pentavalent uranium brannerite phases in glass with the incorporation of yttrium/cerium/europium has been investigated. The formation of brannerite phases in glass has been confirmed with X‐ray diffraction and Raman spectroscopy. The evolution of microstructures and the development of micro pores in brannerite phases have been revealed by scanning electron microscopy with the nominal formula, Y_0.51U_0.49Ti₂O₆, Ce_0.65U_0.35Ti₂O₆, and Eu_0.53U_0.47Ti₂O₆, being determined with energy‐dispersive spectroscopy. The presence of dominant U⁵⁺ species has been proven with both diffuse reflectance spectroscopy and X‐ray absorption near‐edge spectroscopy. In addition, the systematic Raman band shifts with the mean cation radius in the studied brannerite series have been observed and discussed.     

Electrochemical nucleation of uranium in molten chlorides

The electrochemical nucleation of uranium in molten salts on vitreous carbon was studied using chronoamperometry. It is shown that, whatever the applied overpotential and the temperature of the melt, the nucleation of uranium is instantaneous, three-dimensional and controlled by hemispherical diffusion. The diffusion coefficient of UIII is calculated. The value obtained by chronoamperometry is in good agreement with that obtained by cyclic voltammetry in previous studies [1].     

Production of near‐full density uranium nitride microspheres with a hot isostatic press

Depleted uranium nitride (UN) kernels with diameters ranging from 420 to 858 microns and theoretical densities (TD) between 87 and 91 percent were postprocessed using a hot isostatic press (HIP) in an argon gas media. This treatment was shown to increase the TD up to above 97%. Uranium nitride is highly reactive with oxygen. Therefore, a novel crucible design was implemented to remove impurities in the argon gas via in situ gettering to avoid oxidation of the UN kernels. The density before and after each HIP procedure was calculated from average weight, volume, and ellipticity determined with established characterization techniques for particle. Micrographs confirmed the nearly full densification of the particles using the gettering approach and HIP processing parameters investigated in this work.     

Corrosion resistance of AlN-based ceramics to molten uranium

A kind of AlN-based ceramics was prepared as a lining material of the high-density graphite crucible for high temperature melting uranium. During the corrosion experiment, the corrosion rate showed a downward trend with the increase of corrosion time. As the corrosion time increased from 2 h to 8 h, the corrosion rate showed a gradual downward trend from 0.25 mg cm^?2 h^?1 to 0.22 mg cm^?2 h^?1, and then decreased significantly to 0.07 mg cm^?2 h^?1 at 16 h. A dense layer consisting of UO₂, Y₂O₃ and UC was formed between molten uranium and AlN-based ceramics, and the thickness increased with the extension of corrosion time, resulting in a significant decrease in corrosion rate.