堵塞对垂直流人工湿地中酶活性和污染物去除效果的影响

随着人工湿地持续运行,基质堵塞不可避免,了解湿地堵塞后对基质酶活性和污染物去除的影响对基质堵塞后湿地的科学管理有指导意义.该实验通过构建2个垂直流人工湿地模拟系统,通过监测孔隙度变化,初步判定堵塞情况,实验发现该湿地系统堵塞主要发生在10cm～20cm层.从湿地堵塞后酶活性和污染物去除效果变化发现基质堵塞初期对COD去...     

不同进水碳氮比对水平潜流人工湿地脱氮效果的影响

在不同条件下对3种湿地植物枯落物进行水解,以获得相应的植物碳源。利用提取的植物碳源,研究了进水碳氮比对水平潜流人工湿地脱氮效果的影响。结果表明,对以硝态氮为氮源的反硝化过程,补充碳源对硝态氮和总氮的去除有明显的促进作用;对以氨氮和硝态氮为氮源的脱氮过程,随碳氮比的升高,硝态氮和总氮去除率增大,而氨氮由于受到溶解氧的制约,其去除率下降,并最终制约了总氮去除率的增大程度。     

人工湿地中COD、NH4-N去除的研究

采用两段表面流人工湿地处理城市污水。污水经AB法处理后，再经人工湿地处理。第一段人工湿地水力停留时问(HRT)为3d，COD去除率为40％～60％，NH4-N的去除率为50％～70％。第二段人工湿地水力停留时间(HRT)为3d，COD平均去除率大于50％，NH4-N平均去除率大于90％。     

水源地人工湿地水质净化效果及其对浮游植物的影响

以嘉兴市水源地石臼漾湿地和贯泾港湿地两个人工湿地为研究对象,分析人工湿地内的水质变化和浮游植物分布特征,探究人工湿地净化对浮游植物生长和群落结构的影响。观测结果表明,两个湿地总体上属于中、富营养状态的低流速浅水水体,对氮磷营养盐有不同程度的净化效果,浮游植物种属构成基本一致,优势种属为隐藻属、蓝隐藻属、小环藻属、四星藻属、衣藻属;经人工湿地净化后,氮磷营养盐浓度降低,但受水体水动力、透明度等其他因素的影响,出水的叶绿素a浓度和藻类丰度均明显增大,藻类群落结构发生变化,优势种属向蓝隐藻和隐藻转变。     

人工湿地中氨化细菌去除有机氮的效果

人工湿地去除有机氮主要由于氮化细菌的作用。为了了解人工湿地中氨化细菌去除有机氮的效果,对人工湿地基质中5株氨化细菌进行了初步鉴定,比较了不同氨化细菌去除有机氮的效果,氨化细菌去除有机氮的量通过其生成的NH^4＋-N来衡量。结果表明,芽孢杆菌属（Bacillus）、假单胞菌属（Pseudomonas）为人工湿地中氨化细菌的优势菌属：     

人工湿地植物对氮素去除影响机制的研究进展

人工湿地植物通过直接作用与间接生态效应对系统脱氮过程发挥着至关重要的作用.其中,直接作用是湿地植物直接吸收利用无机氮;间接生态效应则是通过植物根系分泌氧和根系物质,以及影响氮素矿化作用,来改善脱氮微生物的生存环境,从而影响脱氮微生物的群落结构及硝化-反硝化过程,实现对湿地系统脱氮的影响.在此基础上,文章进一步阐述了植物...     

三级表面流人工湿地对猪场废水深度净化效果研究

构建三级表面流人工湿地处理低浓度猪场废水并评价其净化效果,同时利用高通量测序技术表征湿地运行前后底泥微生物群落结构变化。低浓度猪场废水中化学需氧量(COD)、总氮(TN)、氨氮(NH₄⁺-N)、总磷(TP)分别为87.7、32.3、29.5、3.3 mg/L,经三级人工湿地处理后出水各指标平均质量浓度分别为20.0、8.7、8.5、0.5 mg/L,即该人工湿地对各指标的去除率分别为77%、73%、71%、84%。表面流人工湿地的运行影响了底泥微生物群落结构,各级人工湿地底泥细菌群落多样性和丰富度均显著高于原始土壤。微生物群落分析表明,酸杆菌门(Acidobacteria)、变形菌门(Proteobacteria)、绿弯菌门(Chloroflexi)以及脱硫菌门(Desulfobacterota)是底泥微生物群落的优势门。基于共线网络分析发现,m(COD)/m(P)、m(N)/m(P)以及TP是影响底泥菌群结构的主要环境因素,其对Acidobacteria以及Desulfobacterota有显著影响。     

污水厂尾水的人工湿地处理工艺及植物筛选

利用土壤作为水平潜流人工湿地的填料,处理某生活污水处理厂的尾水。结果表明该潜流湿地对COD、NH3 N、TN和TP有很好的去除效果,其平均去除率分别达到78．7％、99．3％、67．2％和96．4％。移植土著植物,通过试验筛选出对N去除效果比较好的品种为菖蒲、马兰和石菖蒲,对P去除效果比较好的三种植物为马兰、萱草和菖蒲。     

潜流人工湿地中不同填料介质与进口流速对水动力学性能影响的研究

使用计算流体力学软件对潜流人工湿地的水力学特性进行了模拟计算,通过对不同填料介质和进口流速的模拟比较,讨论不同条件下的湿地水力学行为。模拟结果表明,当上层介质为40~50 mm,下层介质为100 mm时,可以得到较高的湿地水力学效能。进口流速在1e-6m/s至5e-6m/s时,水力学效能变化范围较小,而随着进口流速的进一步增大,水力学效能有较明显的减小趋势。本研究选择进口流速为3.3e-6m/s,以保证达到设计处理量的基础上获得最佳的水力学效能。     

Effects of Secondary Plant Metabolites on Microbial Populations: Changes in Community Structure and Metabolic Activity in Contaminated Environments

Secondary plant metabolites (SPMEs) play an important role in plant survival in the environment and serve to establish ecological relationships between plants and other organisms. Communication between plants and microorganisms via SPMEs contained in root exudates or derived from litter decomposition is an example of this phenomenon. In this review, the general aspects of rhizodeposition together with the significance of terpenes and phenolic compounds are discussed in detail. We focus specifically on the effect of SPMEs on microbial community structure and metabolic activity in environments contaminated by polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Furthermore, a section is devoted to a complex effect of plants and/or their metabolites contained in litter on bioremediation of contaminated sites. New insights are introduced from a study evaluating the effects of SPMEs derived during decomposition of grapefruit peel, lemon peel, and pears on bacterial communities and their ability to degrade PCBs in a long-term contaminated soil. The presented review supports the “secondary compound hypothesis” and demonstrates the potential of SPMEs for increasing the effectiveness of bioremediation processes.     

不同产地坡缕石粘土对高吸水树脂吸水性能的影响

以玉米秸秆,丙烯酸,不同产地坡缕石粘土为原料合成复合高吸水树脂MS-g-PAA/PGS。通过红外光谱,X射线衍射,扫描电镜和热重分析来研究坡缕石粘土的结构和形态。通过红外光谱和扫描电镜对复合高吸水树脂形貌及结构进行了表征。研究了各地坡缕石粘土形态,结构及组成对高吸水树脂吸水保水性能的影响.结果显示添加靖远坡缕石粘土的复合高吸水树脂有着最佳吸水保水性能。     

Effect of process water chemistry and particulate mineralogy on model oilsands separation using a warm slurry extraction process simulation

Variability in ore composition and process parameters is known to affect bitumen recovery from natural oilsands. In this work, we extend our earlier investigations with model oilsands systems (MOS) to determine the effects of calcium, magnesium and bicarbonate ion concentrations in the process water and their interactions with ‘active’ solids such as: kaolinite, montmorillonite and ultra-fine silica. Our results demonstrate that solids mineralogy and decreasing particle size produce negative outcomes on bitumen recovery related to concomitant effects on bitumen droplet size during flotation. In some cases, certain process water chemistries were found to restore recovery, but clay concentration was the key factor.Naturally acidic oilsands are known to give poor bitumen recoveries. An MOS prepared with connate water at pH 2 responded in the same way. Comparison with a typical oilsands showed no significant differences in middlings pH and the large, negative effect on bitumen recovery was not reversed by higher caustic loading during separation. This result may be caused by irreversible co-flocculation of bitumen and mineral particles during preparation of the MOS and may reflect similar behavior in comparable natural samples.     

Adsorptive crystallization of benzoic acid in aerogels from supercritical solutions

In this work, adsorption and crystallization of benzoic acid in different porous carriers (silica aerogel, MCM41, Trisopor glass, zeolite) from supercritical CO₂ solutions is studied. The main purpose is to reveal the influence of the adsorptive properties of the carrier on the crystallization behavior of the solute. Therefore, both adsorption and crystallization processes are studied as a function of carrier's surface properties. Adsorption of the solute and CO₂ is measured in situ using a magnetic suspension balance, whereas crystallization is realized in a high pressure view cell. The carriers could be loaded with up to ∼35 wt.% of benzoic acid, depending on the nature and the amount of the functional groups of the carrier. The size of the benzoic acid particles obtained inside the aerogel matrix depends on the crystallization conditions and is in the range of ∼20 nm-50 μm. The crystallinity of the particles was studied and it is shown that the physical state of the loaded benzoic acid inside the pores of aerogels is influenced by benzoic acid-aerogel surface interactions: strong interactions favor the amorphous form, weak interactions favor crystalline particles. The amorphous form of benzoic acid is shown to be stable over a long time period. Thus, silica aerogels can be used for stabilizing amorphous forms of organic compounds, which can be used for instance in pharmaceutical applications for the improvement of drug bioavailability.     

A review on the mechanical and electrical properties of graphite and modified graphite reinforced polymer composites

Carbon materials particularly in the form of sparkling diamonds have held mankind spellbound for centuries, and in its other forms, like coal and coke continue to serve mankind as a fuel material, like carbon black, carbon fibers, carbon nanofibers and carbon nanotubes meet requirements of reinforcing filler in several applications. All these various forms of carbon are possible because of the element's unique hybridization ability. Graphene (a single two-dimensional layer of carbon atoms bonded together in the hexagonal graphite lattice), the basic building block of graphite, is at the epicenter of present-day materials research because of its high values of Young's modulus, fracture strength, thermal conductivity, specific surface area and fascinating transport phenomena leading to its use in multifarious applications like energy storage materials, liquid crystal devices, mechanical resonators and polymer composites. In this review, we focus on graphite and describe its various modifications for use as modified fillers in polymer matrices for creating polymer-carbon nanocomposites.