2种类型多壁碳纳米管对蛋白核小球藻的毒理研究

碳纳米材料由于其具有优异的性能,得以广泛生产和使用,其不可避免会进入水环境中,对水生生态系统造成潜在影响。多壁碳纳米管(P-MWCNTs)和羟基化多壁碳纳米管(MWCNTs-OH)作为纳米材料的典型代表,应用非常广泛,其潜在的环境效应受到人们越来越多的关注。为此,本文以蛋白核小球藻(Chlorella pyrenoidosa)作为受试生物,通过暴露实验,研究了P-MWCNTs和MWCNTs-OH对蛋白核小球藻的生物学效应。研究结果表明：1)当P-MWCNTs浓度≤10 mg·L-1、MWCNTs-OH≤20 mg·L-1浓度时对蛋白核小球藻生长未造成影响;2)暴露96 h后,当P-MWCNTs≤10 mg·L-1、MWCNTs-OH浓度≤20 mg·L-1时,蛋白核小球藻细胞可溶性蛋白质含量增加,当P-MWCNTs浓度≥20 mg·L-1、MWCNTs-OH浓度≥40 mg·L-1时,2种类型MWCNTs均对蛋白核小球藻造成毒性效应;3)随着2种类型MWCNTs浓度的增加,蛋白核小球藻细胞总抗氧化能力(T-AOC)值减少,蛋白核小球藻细胞丙二醛(MDA)含量显著增加,细胞的健康程度逐渐恶化,细胞结构受到严重损伤;4)MWCNTs-OH比P-MWCNTs具有更好的生物相容性。     

碳纳米材料在环境中的转化

碳纳米材料主要包括富勒烯、碳纳米管和石墨烯.随着碳纳米材料的研究和应用范围不断扩大,其对环境的影响和在环境中的行为也逐渐受到关注,而在环境中的转化是环境行为的一个重要方面.首先,环境转化会改变碳纳米材料的性质,从而影响其它行为如聚集沉降和生态毒性.同时,作为一种以碳为骨架的材料,能否被自然界转化、从而进入碳循环是评价碳纳米材料长期环境影响的必要信息.因此,本文重点总结了碳纳米材料在自然环境条件和水处理条件下可能发生的生物或非生物转化,并分析影响碳纳米材料转化的因素,和转化过程对其环境行为的影响.     

G-CNTs/PVDF mixed matrix membranes with improved antifouling properties and filtration performance

A novel nanocomposite OMWCNT-A-GO was synthesized by conjugating OMWCNT and GO. The P-OMWCNT-A-GO membrane was fabricated by non-solvent induced phase inversion. The P-OMWCNT-A-GO exhibits the best water flux, BSA rejection and flux recovery. It should be due to the enhanced membrane pore size, porosity and hydrophilicity. Although carbon nanomaterials have been widely used as effective nanofillers for fabrication of mixed matrix membranes (MMMs) with outstanding performances, the reproducibility of the fabricated MMMs is still hindered by the non-homogenous dispersion of these carbon nanofillers in membrane substrate. Herein, we report an effective way to improve the compatibility of carbon-based nanomaterials with membrane matrixes. By chemically conjugating the oxidized CNTs (o-CNTs) and GO using hexanediamine as cross-linker, a novel carbon nanohybrid material (G-CNTs) was synthesized, which inherited both the advanced properties of multi-walled carbon nanotubes (CNTs) and graphene oxide (GO). The G-CNTs incorporated polyvinylidene fluoride (PVDF) MMMs (G-CNTs/PVDF) were fabricated via a non-solvent induced phase separation (NIPS) method. The filtration and antifouling performances of G-CNTs/PVDF were evaluated using distillate water and a 1 g/L bovine serum albumin (BSA) aqueous solution under 0.10 MPa. Compared to the MMMs prepared with o-CNTs, GO, the physical mixture of o-CNTs and GO and pure PVDF membrane, the G-CNTs/PVDF membrane exhibited the highest water flux up to 220 L/m²/h and a flux recovery ratio as high as 90%, as well as the best BSA rejection rate. The excellent performances should be attributed to the increased membrane pore size, porosity and hydrophilicity of the resulted membrane. The successful synthesis of the novel nanohybrid G-CNTs provides a new type of nanofillers for MMMs fabrication.     

羧基化多壁碳纳米管对蛋白核小球藻的生物学效应研究

碳纳米材料由于其具有优异的性能,得以广泛生产和使用,因而不可避免地进入水环境中,对水生生态系统造成潜在的影响。羧基化多壁碳纳米管(MWCNTs-COOH)作为功能化多壁碳纳米管的一种,其应用亦非常广泛,其潜在的环境效应受到人们越来越多的关注。以蛋白核小球藻(Chlorella pyrenoidosa)作为受试生物,通过暴露实验研究了MWCNTs-COOH对蛋白核小球藻的生物学效应。研究结果表明:1)MWCNTs-COOH在中高浓度以下(≤20 mg·L~(-1))未对C.pyrenoidosa生长造成影响;2)暴露96 h后,中、高浓度(10、20 mg·L~(-1))促进C.pyrenoidosa细胞可溶性蛋白的合成,但在高浓度(≥40 mg·L~(-1)),MWCNTsCOOH对C.pyrenoidosa造成毒性效应;3)随着MWCNTs-COOH浓度的增加,C.pyrenoidosa细胞总抗氧化能力(T-AOC)值减少,C.pyrenoidosa细胞丙二醛(MDA)含量显著增加,细胞的健康程度逐渐恶化,细胞结构受到严重损伤。     

活性氧参与多壁碳纳米管诱导的RAW264.7细胞毒性

碳纳米管以其独特的结构和性能,在生物医药和电子等领域广泛应用,而其生态安全性也成为科学界关注的焦点。为探究多壁碳纳米管(MWCNTs)诱导的细胞毒性机制,将小鼠肺泡巨噬细胞(RAW264.7)暴露于6个浓度梯度(0、25、50、100、150和200μg.mL-1)的MWCNTs中,应用噻唑蓝(MTT)法测定细胞存活率,用2’,7’-二氯荧光素二乙酸(DCFH-DA)荧光染色法测定细胞内活性氧的生产量,用流式细胞方法测定MWCNTs对细胞周期的影响。同时使用抗氧化剂氮乙酰半胱氨酸(NAC)验证MWCNTs诱导的细胞氧化损伤的作用机理。结果显示,MWCNTs对RAW264.7的细胞毒性呈剂量依赖性。暴露于不同浓度的MWCNTs(25、50、100、150和200μg.mL-1)下24h后,细胞活力分别为对照的74%、62%、59%、51%和45%。MWCNTs对RAW264.7的周期阻滞作用主要发生在G0/G1期。200μg.mL-1的MWCNTs处理3h后活性氧较对照组上升6.6倍。NAC对MWCNTs细胞毒作用有明显的抑制作用,且NAC能减弱MWCNTs对RAW264.7的细胞周期阻滞作用。研究表明,活性氧能够介导MWCNTs对小鼠巨噬细胞RAW264.7的损伤,并且MWCNTS通过细胞周期G0/G1期的阻滞,诱导细胞凋亡。     

免耕覆盖对土壤微生物量碳的影响

通过设置在甘肃省定西县李家堡镇甘肃农业大学旱农实验站的用间定位试验,研究连续3年春小麦(Triticum aestivum)-豌豆(Pisum sativum Linn.)双序列轮作后6种不同处理土壤微生物量碳的变化情况,结果表明:免耕条件下表土层土壤微生物量碳总是显著地高于翻耕土壤;秸秆覆盖表土层和亚表层土壤微生物量碳明显高于不覆盖;不同处理对表土层和亚表层土壤微生物量碳的影响差异达极显著;表土层土壤微生物量碳有明显的季节动态变化;土壤微生物量碳随土层加深而递减.     

生物膜法处理养殖废水的研究

室内模拟研究生物膜法处理养殖废水的效果及其影响因素。实验结果表明，连续曝气或者不曝气，生物膜法对养殖废水中的硝酸盐氮去除效果都很差。曝气条件下生物膜法对CODCrNH4^ -N、NO2^--N均有较好的净化效果，CODCrNH4^ -N、NO2^--N的去除率可分别达到79％、99％、99％；不曝气条件下生物膜法对CODCrH4^ -N、NO2^--N净化效果稍差，CODCrNH4^ -N、NO2^--N的去除率可分别达到78％、35％、76％。曝气会增加养殖废水中PO4^3 -P的质量浓度，增幅可达82％；不曝气时PO4^3 -P的去除率可达63％。投加复合菌株有利于生物膜的形成和处理效果的提高。     

Exigency for fusion of graphene and carbon nanotube with biomaterials

Biomaterial industry is a widely growing field that is closely related to advanced materials. With development in fabrication techniques new materials are being created by researchers daily. The currently used biomaterials for biomedical applications have some limitations. This review examines those limitations such as corrosion, short fatigue life, less wear resistance, and inadequate mechanical properties. These limitations may lead to adverse effects. To overcome these limitations carbon-based nanomaterials may be incorporated such that these biomaterials reach the level of ideal biomaterials. Upgrade of biomaterials with graphene and carbon nanotubes (CNTs) needs to be done only after checking the safety profile of these materials. Biocompatibility of functionalized graphene and CNT is found to be adequate for the use in many applications such as drug delivery, biosensing and imaging, cancer therapeutics, and tissue regeneration whereas pristine graphene and CNT may produce adverse effects. The potential of carbon-based nanomaterials and graphene (and its derivatives) in overcoming those limitations and enhancing biological activities of ongoing biomaterials by acting as composites and coating material is examined. In addition, nanomaterials employ new techniques in biomedical application such as cancer therapy for more efficient results.     

Removal of Janus Green dye from aqueous solutions using oxidized multi-walled carbon nanotubes

Multi-walled carbon nanotubes (MWCNTs) were oxidized and characterized by Fourier transform infrared spectroscopy. The adsorption characteristics of the oxidized MWCNT adsorbent were examined using Janus Green (JG) as adsorbate. In batch tests, the effects of pH, adsorbent dose, contact time, and temperature were studied. The maximum adsorption capacity was found to be 56 mg g^?1. The experimental data were fitted to the Langmuir, Freundlich, and Tempkin isotherm models, the first one being the most appropriate. Kinetic analysis showed that adsorption was most accurately represented by a pseudo-second-order model.     

Removal of nitrogen and phosphorus from textile wastewater by soilless culture of Lolium multiflorum

A technique of soilless culture for removal of total nitrogen (TN) and total phosphorus (TP) from textile wastewater using Lolium multiflorum was conducted in this research. The TN concentration decreased from 50.72 mg/L to 24.64–27.89 mg/L and TP decreased from 6.9 mg/L to 3.7–4.1 mg/L in the experimental tank with the size of 4.7 m x 1.2 m x 0.75 m. The results suggested that L. multiflorum could absorb a large amount of N and P elements from the wastewater. This technique of soilless culture has many advantages such as simple equipment, low cost, easy operation, low energy consumption, convenient management and flexible disposition.     

糖类在城市污水生物处理系统中的去除机理

研究了厌氧、缺氧和好氧状态下淀粉在城市污水生物处理系统中水相和泥相中吸附和降解的动力学参数,建立了淀粉在厌氧、缺氧、好氧状态下的降解动力学模型,并对模型预测的结果进行了验证.结果表明,Fritz-Schlunder模型可以较好地描述糖类在厌氧、缺氧和好氧污泥上的吸附过程,吸附的大分子糖类迅速水解为低一级的高分子物质和小分子物质;厌氧降解速率系数K厌、缺氧的降解速率系数K缺与好氧的降解速率常数的比值分别为0.40和0.64;所建立的动力学模型能较好的预测出水糖类的浓度(相对误差<10%).     

利用污水资源生产微藻生物柴油的关键技术及潜力分析

21世纪人类面临着能源与水资源的双重危机与挑战。微藻制备生物柴油和微藻深度脱氮除磷分别是开发新能源和污水深度处理方面的热点研究,但二者的单一系统均存在一定的局限性。基于微藻培养的污水深度处理与生物柴油生产耦合系统可以克服上述单一系统的局限性,在深度处理污水的同时,以污水为资源制备微藻生物柴油。藻种筛选是耦合系统的前提与重点,其筛选原则为在二级出水条件下生长快、氮磷去除效率高和单位藻细胞油脂含量高。合适的藻细胞分离收获及油脂提取技术能够降低能耗;而油渣厌氧发酵可充分回收其中的能量,同时减少油渣对环境造成的不利影响。根据耦合系统的工艺特点,每年全国利用该耦合工艺以生活污水为原料生产微藻生物柴油的潜力约397万t。     

芦苇人工湿地对农村生活污水磷素的去除及途径

构建了芦苇(Phragmites australis)水平潜流人工湿地处理农村生活污水中的磷素,考察了湿地除磷效果以及地上植物吸磷量。结果表明,人工湿地对磷素的去除随水力停留时间的延长而增加,停留时间大于5.3 d时,芦苇湿地除磷效率可以高于88%。湿地进水TP负荷与磷去除速率之间有较好的线性关系(R2>0.91)。湿地植物在11月份收割时,地上生物量为1.65 kg.m-2,芦苇地上部分吸收磷量为3.68 g.m-2.a-1。分析了湿地除磷途径,在试验条件下,湿地填料的吸附和沉淀等作用是水平潜流人工湿地除磷的主要途径,植物吸收仅占湿地总磷去除量的9.1%,但是湿地水生植物是人工湿地重要组成部分,可以通过影响湿地的其他条件间接影响湿地除磷效果。试验证明,人工湿地是适用于农村地区的优良的污水处理技术。     

Effect of TiO2 nanoparticles and multiwall carbon nanotubes on the freshwater diatom Nitzschia frustulum: evaluation of growth,cellular components and morphology

Great attention should be paid to the possible impacts of various nanoparticles on aquatic organism. Freshwater diatoms are essential components of phytoplankton and play a critical role in bioassessment of nanoparticle exposure in the environment. In this study, cell growth was inhibited by TiO₂-NPs and MWCNTs, the 24?h EC₅₀ values of TiO₂-NPs and MWCNTs to Nitzschia frustulum were 20.75 and 24.64?mg?L^?1, respectively. Significant decreases of Chl a content after TiO₂-NPs exposures were detected and the Chl a content of N. frustulum was obviously increased by MWCNTs treatment at lower concentration. The ROS was detected in N. frustulum after TiO₂-NPs and MWCNTs exposures. The MDA content was significantly induced by TiO₂-NPs at lower concentrations of 24 and 48?h exposure; meanwhile, it increased at all tested concentrations at 24?h MWCNTs exposure. The SOD enzyme was induced by 72 and 96?h TiO₂-NPs exposure, and increased by MWCNTs treatment at 96?h in N. frustulum. Scanning electron microscopy results revealed that N. frustulum had obvious cell deformation after TiO₂-NPs treatment. The result showed that the physiological and biochemical response mechanisms after NPs exposure of diatom were species-specific, and in relation to the exposure concentration and time.     

Upgrade of three municipal wastewater treatment lagoons using a high surface area media

Lagoon-based municipal wastewater treatment plants (WWTPs) are facing difficulties meeting the needs of rapid population growth as well as the more stringent requirements of discharge permits. Three municipal WWTPs were modified using a high surface area media with upgraded fine-bubble aeration systems. Performance data collected showed very promising results in terms of five-day biochemical oxygen demand (BOD₅), ammonia (NH₃) and total suspended solids (TSS) removal. Two-year average ammonia effluents were 4.1 mg·L^-1 for Columbia WWTP, 4 mg·L^-1 for Larchmont WWTP and 2.1 mg·L^-1 for Laurelville WWTP, respectively. Two- year average BOD₅ effluents were 6.8, 4.9 and 2.7 mg·L^-1, and TSS effluents were 15.0, 9.6 and 7.5 mg·L^-1. The systems also showed low fecal coliform (FC) levels in their effluents.     

鼎湖山主要植被类型土壤微生物生物量研究

对鼎湖山国家级自然保护区3种主要植被类型：季风常绿阔叶林，针阔叶混交林和马尾松林土壤微生物生物量进行了研究。结果表明，土壤微生物生物量（mg.kg^-1）在季风常绿阔叶林、针阔叶混交林和马尾松林中分别为：822，588，530，季风常绿阔叶林显著高于针阔叶混交林和马尾松林（P〈0．01），而针阔叶混交林和马尾松林无显著差异（P〉0．05）；土壤中微生物量高的土壤中，有机碳含量也相应高，两者的比值可反应土壤碳的积累或损失，研究表明，鼎湖山3种主要植被类型土壤均处于碳积累过程；季风常绿阔叶林、针阔叶混交林和马尾松林土壤微生物碳周转量（t.hm^-2．a^-1）依次为：14．07，11．45，9，60，碳素的周转带动了其他营养元素的循环和能量的流动；土壤微生物代谢熵（mg.g^-1．h^-1）由低到高依次是季风常绿阔叶林（0．59）、针阔叶混交林（0．96）和马尾松林（1．33），表明土壤微生物对土壤碳的利用效率季风常绿阔叶林较高，马尾松林较低。     

Enzymatic nitrous oxide emissions from wastewater treatment

Nitrous oxide (N₂O), a potent greenhouse gas, is emitted during nitrogen removal in wastewater treatment, significantly contributing to greenhouse effect. Nitrogen removal generally involves nitrification and denitrification catalyzed by specific enzymes. N₂O production and consumption vary considerably in response to specific enzyme-catalyzed nitrogen imbalances, but the mechanisms are not yet completely understood. Studying the regulation of related enzymes’ activity is essential to minimize N₂O emissions during wastewater treatment. This paper aims to review the poorly understood related enzymes that most commonly involved in producing and consuming N₂O in terms of their nature, structure and catalytic mechanisms. The pathways of N₂O emission during wastewater treatment are briefly introduced. The key environmental factors influencing N₂O emission through regulatory enzymes are summarized and the enzyme-based mechanisms are revealed. Several enzymebased techniques for mitigating N₂O emissions directly or indirectly are proposed. Finally, areas for further research on N₂O release during wastewater treatment are discussed.

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三维电极电化学反应器组合Fenton试剂深度处理焦化废水

采用三维电极电化学反应器组合Fenton试剂法对经过二级生化处理后的焦化废水进行深度处理。在三维电极参数一定的条件下,考察了影nfi]TOC去除率的影响因素,探讨了该反应体系的降解动力学及降解机理。正交试验结果表明,反应体系中各参数的最佳值分别为p（H202投加量）=300mg·L-1,pH3．4,反应时间为90min,c（FeS04-7H20投加量）为3．5mmol·L-1,TOC去除率可达到61．7％。焦化废水的降解反应表现为一级动力学。紫外吸收光谱分析结果,废水中有机物彻底发生了降解矿化,这为三维电极组合Fenton试剂工艺在焦化废水深度处理中的工程应用提供了一定的理论指导。     

Combined process of biofiltration and ozone oxidation as an advanced treatment process for wastewater reuse

The effluent of a wastewater treatment plant was treated in a pilot plant for reclaimed water production through the denitrification biofilter (DNBF) process, ozonation (O₃), and biologic aerated filtration (BAF). The combined process demonstrated good removal performance of conventional pollutants, including concentrations of chemical oxygen demand (27.8 mg·L⁻¹) and total nitrogen (9.9 mg·L⁻¹) in the final effluent, which met the local discharge standards and water reuse purposes. Micropollutants (e.g., antibiotics and endocrine-disrupting chemicals) were also significantly removed during the proposed process. Ozonation exhibited high antibiotic removal efficiencies, especially for tetracycline (94%). However, micropollutant removal efficiency was negatively affected by the nitrite produced by DNBF. Acute toxicity variations of the combined process were estimated by utilizing luminescent bacteria. Inhibition rate increased from 9% to 15% during ozonation. Carbonyl compound concentrations (e.g., aldehydes and ketones) also increased by 58% as by-products, which consequently increased toxicity. However, toxicity eventually became as low as that of the influent because the by-products were effectively removed by BAF. The combined DNBF/O₃/BAF process is suitable for the advanced treatment of reclaimed water because it can thoroughly remove pollutants and toxicity.     

流化床三维电极电催化氧化深度处理焦化废水

研究了以焦粒为粒子电极的流化床三维电极反应器对二级生化处理后的焦化废水进行深度处理。结果表明：采用以焦粒为粒子电极的流化床三维电极反应器能有效降解废水中的有机物,COD去除率依赖于粒子投加量、电流密度、电导率、pH值、曝气量等操作参数的影响。在电导率（以S计）为7.1 m.cm-1,曝气量为160 L.h-1,电流密度（以A计）为48 m.cm-2,pH值为5.0,投加量30 g.L-1时,电解30 min,COD的去除率超过60%,表明流化床三维电极反应器在焦化废水深度处理中有很好工程应用前景。