国内城市黑臭水体内源污染治理技术研究进展

城市黑臭水体不仅影响景观,还会威胁人类健康。其中,内源污染是水体污染的重要来源。文章对内源污染的形成及危害、异位和原位治理技术定义及优缺点等内容进行了总结。主要结论如下:底泥清淤能快速转移污染底泥,但易破坏水底的生态系统,且会给环境带来二次污染;底泥覆盖能减少底泥污染物向水体释放,但不能移除污染物,仍存在污染物释放到水体的风险;投放化学药剂能有效去除污染物,但可能带来水体毒性以及引起污染物的异常释放,一般适用于应急处理;微生物修复底泥效果好,但目前还处于实验室和中试试验阶段;底泥曝气能加快底泥复氧速度,有效改善黑臭水体污染情况,但其耗能高,受设备因素限制而少应用于实践。在城市黑臭水体内源治理实际工程中,应依据不同治理技术的优缺点制定具体实施方案,以修复城市水体生态环境。     

两种覆盖材料阻隔湖泊污染底泥磷释放的研究

本研究建立了一套模拟湖泊小试装置,分别采用含粘土的沙子和清洁黄土两种材料覆盖污染底泥阻隔磷释放。实验控制在恒温25℃厌氧条件下进行。经过60d静置和15d扰动实验,结果表明,沙子和黄土覆盖厚度达到5cm以上,均能有效抑制底泥P释放,且覆盖厚度越厚,抑制P释放的效果越好。因此,从工程成本和取材方便的角度考虑,采用5cm~15cm厚度即可。扰动会加速促进底泥P释放,采用覆盖法控制内源磷污染时,要尽量减少对覆盖材料的扰动。     

疏浚水流扰动作用下的河道底泥污染物释放效应

河流湖泊疏浚时,由机械扰动水流造成的底泥再悬浮污染物释放作用十分明显。通过循环长直水槽试验,研究了水动力学条件对底泥污染物内源释放效应的影响。分别在上覆水体静止和流动情况下,分析了水体CODcr,的变化规律。结果表明水体的自净作用在动水条件下显著增强。动态水流通过减小底泥一水界面浓度边界层厚度和破坏底泥一水界面底泥表面结构,增大底泥污染物释放速率和通量。底泥CODcr释放量随着流速的增加而增大,随着水深的增加而减小。但是在水深较浅时,波浪会破坏底泥表层结构,引起底泥污染物的再悬浮释放。单位时间单位面积底泥污染物释放量随着时间的增加而迂回减小,底泥内部污染物向泥一水界面的扩散维持了底泥内源释放效应。     

河道污染底泥处理技术

河道底泥既是接纳河道水体污染物的"沉积库",也是向上覆水释放污染物的"源"。污染底泥是河道主要污染源之一,对河道水环境影响很大。随着河道外源污染的有效控制和河道水体治理的推进,污染底泥引起的内源污染问题日益突出,亟需对河道底泥进行修复和底泥污染物的释放予以控制。本文综述了河道底泥修复技术现状,并对污染河道底泥修复技术提出了展望。     

河道底泥处理的研究

河道底泥作为水体的重要组成部分,累积了大量的污染物,尤其是当外源污染得到有效控制后,沉积在底泥中的氮、磷、重金属等污染物会再次从底泥释放到上覆水体中来,对水体造成严重的污染。因此,良好的底泥生态环境对于水环境污染控制具有重要意义。主要从底泥异位处理和原位处理两大方面,列举了一些底泥修复方式,并对未来的河道底泥处理提出了一些建议和展望。     

镧改性沸石覆盖控制河道底泥污染物释放实验研究

通过模拟实验,考察了天然沸石和镧改性沸石对于黑臭河道底泥污染物释放的处理效果。结果表明,由于底泥释放,空白对照组中上覆水体的污染物浓度出现不同程度的上升。天然沸石组和镧改性沸石组均可降低上覆水体中化学需氧量及氨氮、总磷等的浓度。30d后,镧改性沸石组中水体的化学需氧量、氨氮、总磷分别下降了13.2%、23.4%、55.2%,其中对于总磷的去除效率明显优于天然沸石组。     

不同底泥稳定剂改善富营养化水体技术研究

河道污染底泥原位处理是一种高效、经济、便捷的处理方法。本研究以河道底泥和上覆水为研究对象,对比分析底泥、底泥+硝酸钙、底泥+过氧化钙、底泥+1∶1硝酸钙和过氧化钙、底泥+EM菌剂对于河道底泥氮磷释放抑制和上覆水体改善效果。研究结果表明:与空白底泥相比,实验组在一定程度上都可以抑制底泥氮磷释放,促进上覆水体水质改善。但由于受温度、光照和底泥扰动不同,添加底泥稳定剂对于不同深度上覆水体修复情况存在差异。     

河道水体水质对底泥污染物释放的影响

底泥内源污染物的释放是河道污染的重要因素之一。本文通过模拟试验研究了河道水体水质对底泥污染物释放规律的影响。结果表明:上覆水体pH的升高可使底泥中COD_(Cr)和NH_4~+-N的释放受到抑制,但会促进底泥TN的释放,酸性或碱性条件都会促进底泥中TP的释放;上覆水体有机物浓度的增加可抑制底泥NH_4~+-N和TN的释放,促进TP的释放;溶解氧的增加对底泥COD_(cr)、NH_4~+-N和TN的释放有促进作用,但会抑制底泥中TP的释放。对比分析表明,上覆水体溶解氧(10 mg/L)对底泥COD_(Cr)、NH_4~+-N和TN的释放量影响最大,pH(4.0～10.0)对TP的释放量影响最为显著,累积释放量极差达5.89 mg/kg。     

影响环保疏浚的相关因素和工艺优化探讨

当前,我国的江河湖泊的泥沙淤积和污染问题日益严重。而江河湖泊是底泥污染物的主要蓄积场所,水体污染可以分为内源污染以及外源污染,经过研究表明,即使污染水体在有效控制外源之后,底泥将会逐渐的释放出其中的营养盐,仍旧会导致江河湖泊产生富营养化。所以,对于严重污染的底泥进行环保疏浚工程具有重要的意义。环保数据是对于内源污染快速清除的一个有效方式,但是因为疏浚过程中的扩散、挖泥精度、疏浚底泥的干化、余水的处理、底泥脱水的资源化利用等众多方面的影响,导致环保疏浚仍旧没有取得良好的效果。本文对于环保疏浚过程中产生影响的相关因素进行分析,并探讨其工艺优化措施。     

水体内源污染控制技术

内源污染是当今水环境治理亟待解决的重难点问题之一。目前,内源污染常用的控制技术包括底泥疏浚、原位覆盖、引水冲污、化学修复、水生动植物修复、微生物菌剂以及多种技术联用等。本文以物理修复、化学修复、生物修复3种技术为例,对比分析国内外常用治理内源污染的技术,讨论了各类底泥修复技术措施的优缺点及适用范围。最后,分析了当下内源污染控制存在的问题并进行展望。     

The effect of capping with natural and modified zeolites on the release of phosphorus and organic contaminants from river sediment

A microcosm system that included river sediment, water and different zeolite capping materials (natural zeolite, surfactant-modified zeolite (SMZ), or aluminum modified zeolite (AMZ)) was designed to study the effect of capping on the release of phosphorus and three organic pollutants (phenol, pyridine, and pyrene) from the sediment to the overlying water over the course of three month. For the same amount of the three capping materials, the efficiency of phosphorus inactivation was in the order of SMZ>AMZ>natural zeolite. The inactivation of phosphorus was mainly caused by the covering effect, co-precipitation and adsorption by the capping materials. The different zeolites gave different results for the release of phenol, pyridine, and pyrene from the sediment. When natural zeolite was used as the capping material, there was no effect on the release of pyrene and pyridine, whereas capping the sediment with SMZ or AMZ inhibited the release of pyrene and pyridine but to different extents. However, for controlling the release of phenol from the sediment, aluminum modified zeolite was the most efficient material, whereas no effects were observed when natural zeolite or SMZ were used. The different capabilities of the zeolite materials for controlling the release of different organic pollutants are related to the differences in the electrical properties of these pollutants.     

大同盆地云冈地区云岗组石窟段沉积相特征研究

大同盆地云冈地区主要出露中侏罗统陆源碎屑岩层系,其中云冈组石窟段是"云冈石窟"所开凿层段。本文通过对野外剖面的实测,精细划分了云冈组石窟段的沉积构造单元;结合区域沉积背景,明确了其沉积相的类型与纵向演化特征。所测剖面根据沉积结构及岩性组合特征可进一步划分为八个沉积构造层,总体表现为砂厚泥薄,由砂包泥逐渐变为砂泥互层的特征。综合分析表明,石窟段沉积期研究区以典型的辫状河沉积为主,发育河床滞留沉积、心滩和河漫滩三种典型的沉积微相;期间也间断发育由辫状河向曲流河过渡阶段的沉积;辫状河沉积和过渡阶段的沉积具有一定旋回性。该段地层沉积结构、沉积相类型及其演化特征的明确为大同盆地侏罗纪沉积环境演化及古迹保护研究提供了地质依据。     

Reuse of local sand: effect of limestone filler proportion on the rheological and mechanical properties of different sand concretes

This work aims at the promotion of local sand reuse. Two main objectives are present in this research work: (1) to study the possibility of exploiting local sand available in large quantities in a sand concrete and (2) to partially find a solution to substitute scarce coarse aggregate in concrete. Fillers, which derive from calcareous wastes, are utilized to correct the particle size distribution of sands. For this investigation, three distinct sands have been used: a dune sand (DS), a river sand (RS), and a mixture of dune and river sand in predetermined proportions. After characterizing the materials used, the mixture design of the three corresponding sand concretes has been optimized on the basis of compactness and workability criteria. The influence of filler limestone has, in particular, been examined. A microstructural investigation has provided a better analysis of the mechanical behavior of the derived materials.This study shows the importance of both filler concentration and sand particle size distribution. Using a mixture of dune and river sands in predetermined proportions, in association with limestone filler, allows to obtain a more workable, more compact, and more resistant sand concrete.     

生物油蒸馏残渣与废弃塑料催化共热解协同作用的研究

利用热重分析仪和两段式固定床研究了生物油蒸馏残渣(DR)与废弃塑料(MS)的共热解特性,探索了DR与MS混合比、无催化、原位催化及异位催化对产物分布及液相产物化学组分的影响,以及共热解产物的相对选择性与协同作用。结果表明：随着混合比的增加,液相产率呈现增长趋势;相比于无催化,原位催化、异位催化下液相产物中芳烃相对含量增高、含氧化合物相对含量降低。在原位催化下,DR与MS在脂肪族化合物与含氧化合物上表现出的协同作用与异位催化、无催化相反。对于单环芳烃,DR与MS的协同作用参数值大小关系为：无催化>异位催化>原位催化;对于脂肪烃,在DR∶MS=1∶1时,无催化、原位与异位催化下的协同作用参数最大,分别为-20.7%、25.2%、-41.2%;对于脂环烃,在DR∶MS=2∶1时,无催化、原位与异位催化下的协同作用参数最大,分别为184.2%、132.5%、50.0%;对于多环芳烃,DR与MS在不同催化方式下均表现为负协同作用。     

A model for volatiles release into a bubbling fluidized-bed combustor

A volatiles release model has been developed to predict the location and quantity of coal volatiles that are released into a bubbling fluidized-bed combustor, using overbed, in-bed or underbed feed systems. This model not only considers time resolution of the simultaneous processes of coal devolatilization and coal particle movement after injection, but also takes account of the stochastic nature of this particle movement. Volatiles release is nonuniform, occurring throughout an industrial-scale bed, but only in restricted parts of a laboratory-scale bed. For the industrial-scale bed, 32% of volatiles are released directly into the freeboard while the particle is devolatilizing at the surface, whereas 24% are released there for the laboratory scale bed. The model predicts the formation of numerous discrete volatiles regions within the bed, in agreement with a new interpretation of experimental measurements from an in-bed oxygen probe. The model is shown to be consistent with other experimental in-bed measurements obtained during combustion of “simulated” volatiles.     

城市水源水库及入库河流沉积物中总有机碳和黑碳的时空分异及其对多溴二苯醚的影响

为了解城市水源水库沉积物中总有机碳（TOC）和黑碳（BC）的时空分异及其对典型持久性有机污染物（POPs）——多溴二苯醚（PBDEs）的影响,本文分析了泉州山美水库及入库河流沉积物中TOC和BC的含量、赋存总量、空间分布、水文期变化、BC和TOC的关系及两者对PBDEs时空分异的影响。结果表明：TOC和BC含量分别为15.08mg/g±2.70mg/g（10.87~19.61mg/g）和3.55mg/g±1.14mg/g（2.08~6.92mg/g）,赋存总量分别为107445t和25294t,较国内外其他湖库处于中低水平。TOC和BC的时空分异规律存在差异,TOC主要受水文期变化的显著影响（P<0.001）,而BC则受空间分布的显著影响（P=0.001）。TOC与BC无显著相关性（P≥0.226）,显示两者来源不同,TOC较BC更易受到入库河流输入的影响。山美水库各水文期BC/TOC（丰水0.24±0.09、枯水0.21±0.06、平水0.27±0.08）均介于0.11~0.5,显示其BC为生物质燃烧和部分化石燃料燃烧的复合来源。入库河流BC受生物质燃烧源的影响大于库区。ΣPBDEs、Deca-BDE和Nona-BDE的时空分异受到了TOC的显著影响,且Deca-BDE降解产生的主要低溴BDE的时空分异也受到了TOC不同程度的影响。各水文期TOC和PBDEs的主要污染源相同,均为入库河流,且二者空间分布规律大致相同,TOC是PBDEs时空分异的重要控制因素。各水文期BC与PBDEs因来源不同而均无显著相关性,但BC可大量吸附固定局地污染源释放的PBDEs,对其时空分异仍有重要影响。     

Investigation on catalytic distillation for ethyl acetate production with different catalytic packing structures

The catalytic packing is the core component of the catalytic distillation, and how the catalyst exists in the packing has significant influence on the process. To investigate the effect of catalyst packings on the catalytic distillation process, the classical ethyl acetate reactive distillation system was utilized, and a supported catalytic packing(SCP) was prepared in comparison with the conventional tea-bag catalytic packing(TBP). Laboratory scale experiments showed that the ethyl acetate conv...     

Optical properties and characteristics of the cdse nanoparticles synthesized at room temperature

CdSe nanoparticles were synthesized by using colloidal methods at room temperature. Nanoparticle size was controlled by the amount of stabilizer, pH, and stabilizer type and was characterized by TEM and XRD. All the synthesized CdSe nanoparticles showed the quantum confinement effect. With increased amounts of mercaptoacetic acid as a stabilizer, the size of nanoparticles decreased. The UV-VIS absorption and photoluminescence (PL) properties could also be tailored by controlling particle size. The solubility in organic solvent and the PL characteristics were enhanced through surface capping by an organic passivator.     

THE RELATION OF TEXTURE AND COMPOSITION OF CLAYS1

Twelve Minnesota clays of diverse origin and character, which had been analyzed, were separated mechanically into five fractions, from coarse sand to fine clay, and each fraction was analyzed. Silica is at a maximum in the find sand portion of most clays. Alumina, iron oxides and potash are at a minimum in this portion, but while they rise a little in the coarse sand, they reach their highest proportion in the find clay portion. Other oxides show less regularity. An estimate of the minerals is made on the basis of all available information though it may never be possible to tell how much colloidal material is present, making the calculation inaccurate. It seems clear that kaolinite and limonite are larger in clays than in silts, while quartz and carbonates are smaller. Others are less regular. A detailed comparison of “fluxing constituents” and the temperatures of viscous fusion, led to the suggestion that the behavior of a clay in firing is determined not so much by the total fluxes as by the proportion of fluxes in the fine clay fraction. If this proves to be true, as it seems to be in the Minnesota clays, it should be possible to foretell more accurately than heretofore, the thermochemical and physical changes, on the basis of preliminary laboratory work. Not only the firing of the clay itself, but its effect on admixtures of other clays and its modification by washing can be fairly well estimated from a combined mechanical and chemical test.     

Efficient elimination of environmental pollutants through sorption-reduction and photocatalytic degradation using nanomaterials

With the rapid development of industrial, large amounts of different inorganic and organic pollutants are released into the natural environments. The efficient elimination of environmental pollutants, i.e., photocatalytic degradation of persistent organic pollutants into nontoxic organic/inorganic chemicals, in-situ solidification or sorption-reduction of heavy metal ions, is crucial to protect the environment. Nanomaterials with large surface area, active sites and abundant functional groups could form strong surface complexes with different kinds of pollutants and thereby could efficiently eliminate the pollutants from the aqueous solutions. In this review, we mainly focused on the recent works about the synthesis of nanomaterials and their applications in the efficient elimination of different organic and inorganic pollutants from wastewater and discussed the interaction mechanism from batch experimental results, the advanced spectroscopy techniques and theoretical calculations. The adsorption and the photocatalytic reduction of organic pollutants and the sorption/reduction of heavy metal ions are generally considered as the main methods to decrease the concentration of pollutants in the natural environment. This review highlights a new way for the real applications of novel nanomaterials in environmental pollution management, especially for the undergraduate students to understand the recent works in the elimination of different kinds of inorganic and organic chemicals in the natural environmental pollution management.