淀山湖千墩浦河口生态浮床试验工程净化效果

在淀山湖千墩浦河口实施生态浮床试验工程,利用多种水生植物浮床系统净化水质.结果表明:浮床区DO质量浓度比千墩浦来水、浮床区进水分别提高2.06、0.38 mg/L,透明度分别提高8.1、7.4 cm;浮床区的Chl-a质量浓度年均值均小于20 μg/L;浮床试验工程对千墩浦来水TN、TP、COD、SS的去除负荷分别为1...     

The coupling between hydrodynamic and purification efficiencies of ecological porous spur-dike in field drainage ditch

In this study, a series of ecological porous spur-dikes are arranged in an experiment channel to simulate a real field drainage ditch. The inside and outside flow fields of spur-dikes are determined by numerical simulations and experimental methods. An Ammonia-Nitrogen(NH_3-N) degradation evaluation model is built to calculate the pollution removal rate by coupling with the inner flow field of the porous spur-dikes. The variations of the total pollutant removal rate in the channel are discussed in terms of different porosities and gap distances between spur-dikes and inlet flow velocities. It is indicated that a reasonable parameter matching of the porosity and the gap distance with the flow velocity of the ditch can bring about a satisfactory purification efficiency with a small delivery quantity of ecological porous materials.     

不同布设方式的生态浮床对水流结构影响研究

生态浮床是一种应用广泛的水质净化水体修复技术。在河道中布设生态浮床会干扰水流结构,影响河道行洪排涝能力。本文区分低透水性浮床主体区和高透水性浮床根系区,运用两层式固定多孔介质域概化生态浮床,构建生态浮床不同布设方式的水槽三维水动力数学模型,对比分析无浮床、浮床不同间距串联或交错排列等14种工况的水槽水动力特性及其变化规律。布设浮床后浮床上游水面壅高、下游水面先局部降低后恢复,浮床段流速垂线分布呈"纺锤形"且平均流速和紊动能明显增大。相较于串联排列,交错排列方式对水流结构影响程度较大,且水位、流速、紊动能等水动力参数随浮床间距的变化趋势相异。因此,考虑对洪水位的壅高及增强水流紊动强度利于污染物扩散,实际应用中需结合研究成果合理选择生态浮床的布设方式。     

卵砾石生态河床对河流水质净化和生态修复的效果

为研究卵砾石生态河床在河流原位水质净化和生态修复中的效果,选择位于宜兴市大浦镇的林庄港作为试验河道进行原位观测,对比分析了卵砾石生态河床河段和自然河床河段中的生源要素变化规律和水生生物生长状况。试验结果表明:卵砾石生态河床河段对污染物质的截留效果明显好于自然河床河段,对氨氮和总磷的截留率可分别达到37%和25%,卵砾石生态河床的构建可显著提高河道的自净能力;卵砾石生态河床河段水生植被的生长密度和覆盖率均达到良好的水平,大型底栖无脊椎动物在敏感物种数、分类单元数和生物数量密度等方面均优于自然河段的;卵砾石生态河床为水生植物、底栖动物和附着生物等水生生物提供了适宜的栖息环境,对河流生态系统的健康起到了较好的改善作用。     

一种新型的复合生态浮床及其对浮游植物群落结构的影响

利用现场水池实验法,设可提供生境的复合生态浮床、普通生态浮床、空白对照3组实验处理,对比研究复合浮床与普通浮床在影响浮游植物群落结构及水质净化、生态修复方面的特点和优势。结果表明:复合浮床对N、P的去除率高于普通浮床;复合浮床和普通浮床两者的净化修复作用可抑制水体中浮游植物的大幅度增长,且复合浮床更有助于增加浮游植物的多样性、提高水生态系统的稳定性。     

水动力条件对水体自净作用的影响

通过水槽实验和理论分析,研究了水动力条件对水体自净作用的影响,发现水流流速是影响水体自净作用的主要因素之一,不同断面及水深条件下水体自净作用的差别不是特别明显。分别采用生化需氧量-溶解氧耦合模型和化学一级反应拟合并预测了水质随时间的变化关系。水流流速的增加在一定程度上提高了水体复氧能力,增强了水体的自净作用。当流速超过一个临界值使得底泥再悬浮发生时,水体自净作用在短时间内急剧降低。在引水工程中,合理控制和设计水力参数(流速流量、取水周期及间隔、增加消能水工建筑物)是控制水体水质的有效措施。     

生物质碳源与非生物质填料组合生态浮床净化水体效果

为提升生态浮床对水体的净化效果,以无碳填料为对照,选用生物质碳源(玉米芯)与沸石制备碳源复合填料,分别添加到菖蒲+旱伞草、美人蕉+旱伞草、美人蕉+菖蒲3种植物组合构建的组合生态浮床中,以研究生物质碳源复合填料生态浮床对氮、磷和有机物的去除效果及浮床植物的生长特性.结果表明:复合碳源填料对促进植物生长和提升生态浮床的净化...     

The effect of operational conditions on the hydrodynamic characteristics of the sludge bed in UASB reactors

This work aims to evaluate the hydrodynamic properties of the sludge bed of Upflow Anaerobic Sludge Blanket (UASB) reactors based on its settleability and expansion characteristics. The methodologies used for the evaluation of the settleability of aerobic activated sludge, and for the expansibility of a sludge bed of Expanded Granular Sludge Bed reactors and Fluidised Bed Reactors were adapted and applied to the particular characteristics of the sludge of UASB reactors. An easy-to-build experimental set-up was developed to assess the parameters necessary for the equations of settleability and of expansibility. The results obtained from the sludges of seven differently operated reactors show that, for the treatment of low strength wastewater, settleability increased and expansibility decreased at decreased hydraulic retention time, from 6 to 1 h, and/or increased influent concentrations, from 136 to approximately 800 mg chemical oxygen demand/L. The results also show that it is useless to design an UASB reactor with a longer hydraulic retention time to cope with hydraulic shock loads, as a more expansible sludge will develop at such condition.     

不同水头与流量条件下堤防梯形决口水流特性数值模拟

本文对有矩形障碍物的溃坝算例进行模拟验证,将FLOW-3D计算的速度场结果与FLUENT、Wang的结果进行对比,三者结果基本一致,验证了Flow-3D软件用于堤防决口三维数值模拟的可行性.采用某实际河道堤防简化建模,建立了在决口口门形状、尺寸一定的条件下,上游不同水头、不同流量工况下的堤防决口三维数值模拟.分析结果表明:不同水头、不同流量作用下决口较大的流速平面分布主要分布在决口上游进口左侧发生水跌处.因此,在进行决口封堵时,应注意预先做好决口上游侧的裹头处理,防止在封堵的过程中因流速过大导致溃口口门扩宽;在选取封堵材料时,也可根据溃口处流速分布来选择相应的封堵料粒径.     

枢纽不同泄流方式的水流恢复距离研究

计算水流的恢复距离,可以分析下游引航道口门区的通航水流条件是否受到了上游电站在不同泄流工况下的影响,进而可为电站的调度运行提供参考。以景洪电站为研究背景,分析了发电、控泄发电及敞泄停机这3种工况下的水流沿程分布情况,并与无坝全断面泄流工况的水流沿程分布情况进行比较,提出了水流恢复距离的概念,计算了不同工况下的水流恢复距离。结果表明,两侧泄流的恢复距离均大于中段泄流的恢复距离,泄流宽度所占的比例越大,恢复距离越短,泄流流量越大,恢复距离越长。通过对全断面泄流工况和极限泄流工况在引航道口门区水流条件的对比可知,当水流恢复距离大于引航道的长度时,相对应的泄流工况会造成引航道口门区水流条件明显的变化,此时需要考虑电站泄流对下游通航的影响。     

不规则实体堰坝流场及应力场耦合分析

针对现有堰坝稳定计算方法存在模型概化简单,无法准确反映不规则堰坝的流场及应力分布的问题,基于有限元软件ANSYS Workbench,通过引入气液两相流来求解堰坝的表面流场和水压力,将流场计算结果耦合到结构力学分析中实现某不规则实体堰坝的应力及变形分析。计算结果表明,设计洪水位和常水位工况下堰坝压应力均满足地基承载力要求,且堰体内部未出现拉应力;堰坝整体变形分布合理,能很好地反映堰体与基础非连续性的变形情况。该方法可有效地解决堰坝三维形态复杂及表面压力分布不均所带来稳定分析困难,可为堰坝设计提供依据。     

不同水动力条件下的河流硅藻群落分布机理研究

水体生物种群指标与河流水动力参数之间的关系是水生态的重要研究课题之一。在西江水系柳江河流共设置31个硅藻采样点,来探究表层沉积硅藻在不同水动力条件下的群落结构,着重研究了硅藻与水深、流速和流量等水文变量间的关系。在研究区域共发现硅藻2纲38属264种,通过层状图和排序分析,流速是影响硅藻群落分布最主要的水动力条件,其次才是雷诺数。雷诺数的大小和浮游种类丰度关系紧密,但雷诺数对硅藻种类的影响还有不确定因数。直链藻和小环藻等浮游种类在大江中比小溪中较易出现,同时人工修建的大坝通过改变水动力条件,对藻类的分布产生影响,尤其在水库下游等较极端的湍流条件下,桥弯藻和脆杆藻的丰度明显地增长。     

不同面积浮板覆盖下干旱区平原水库防蒸发节水效率分析

为探究物理技术抑制干旱区平原水库水分的无效蒸发的可行性,本实验使用PVC泡沫浮板做为水面覆盖材料。将浮板连接为试验所需要的不同面积,观察并记录各面积浮板在试验区域自由漂浮时的工作情况。以受风速影响的浮板湿润率为变量,统计试验期内的风速情况和不同风速下各面积的浮板湿润率,从而计算出不同面积的浮板在试验期内的蒸发抑制率。结果表明:当浮板面积从1 m~2增大到16 m~2时,其平均蒸发抑制率从74%增大到88.3%,证明了大面积覆盖水库表面抑制水分蒸发的可行性,为西北干旱区平原水库早日实现物理技术抑制水面蒸发的工程措施奠定了理论基础。     

二维水力模拟在河流生态需水湿周法中的应用

湿周法是河流生态需水量计算中使用较为常见的一种水力学方法,通常采用一维的水力分析结果作为计算依据。二维水力模拟能提供更为细致全面的河道水力参数分布,通过对某水电站坝下13.3 km河道进行平面二维水力模拟,对其在湿周法中的应用进行了探讨。采用弗汝德数(Fr)作为浅滩生境划分标准,把浅滩生境较为集中的河段作为湿周法分析的浅滩河段。随后根据平面二维水力模拟结果,给出了浅滩断面相对湿周-流量关系曲线,采用斜率为1的斜率法计算得到了各浅滩断面的生态需水量。结果表明,采用二维水力模拟结果给出的曲线更为合理。     

均匀流与振荡流作用下圆柱横向振荡水动力特性研究

真实海洋环境中由于波浪场的存在,单纯均匀流较少,研究均匀流与振荡流共同作用对圆柱横向振荡的影响显得十分必要。为此,在验证数值方法可靠的基础上,通过改变振荡流强度和运动圆柱的振幅和频率,分析圆柱所受作用力的变化特性。研究表明:升力系数的变化规律既受振荡流强度的影响也受圆柱振幅比的影响;振荡流弱且圆柱振幅比较小时,圆柱体受力、锁定和拍频与均匀流单独作用时相似;增大振荡流强度后,圆柱体的升力系数幅值一直较大,且尾流中漩涡脱落没有明显的规律。     

Effects of surfactant on bubble hydrodynamic behavior under flotation-related conditions in wastewater

Bubble behavior is fundamental to the performance of froth flotation operations used in wastewater treatment processes. To fully understand and characterize bubble behavior under flotation-related conditions in wastewater, the high-speed photographic method has been employed to examine the motion of single bubbles and size distribution of bubble swarms with intermediate sizes ranging from 1 to 4 mm in the presence of surfactants in a laboratory scale flotation column. Both distilled water and synthetic municipal wastewater have been used to make solutions as well as two types of common surfactants. The instantaneous bubble motion has been recorded by a high speed camera. Subsequently, bubble trajectory, dimensions, velocity and distribution have been determined from the recorded frames using the image analysis software. The experimental results show that the addition of surfactant into wastewater has similar effects on bubble hydrodynamic behavior as in pure water (e.g., improving trajectory stabilization, dampening bubble deformation, slowing down terminal velocity, reducing bubble size and increasing the specific surface area of bubble swarm) due to the Marangoni effect. However, it is interesting to note that surfactant effects on single bubble hydrodynamics in wastewater are slightly stronger than those in pure water while surfactant effects on size parameters of bubble swarms in wastewater are significantly stronger than those in pure water. This finding suggests that besides surfactant, inorganic salts present in synthetic wastewater have an important influence on bubble dispersion.     

河流生态状况分级系统及其应用

构建河流生态状况分级系统可为实现河流生态修复目标定量化提供技术方法。本文从自然河流生态状况的河流参照系统选择与构建出发,依据与参照系统的偏离程度,提出了河流生态状况分级系统的生态指标矩阵方法和指标赋值准则。生态指标矩阵由要素层和指标层构成,包括生物质量、水文、物理化学和河流地貌4个要素,下设10项生态指标。从河流生态系统演替的动态特征出发,阐述了河流生态状况分级系统的科学内涵,讨论了河流生态状况分级系统在确定生态修复目标、识别关键胁迫因子以及进行河流健康评估方面的应用。     

Effects of bed slope on the flow field of vertical slot fishways

Vertical slot fishways (VSFs) are the most efficient and least selective typology of technical fish passage, due to their ability to remain effective even when significant upstream and/or downstream water level fluctuations occur. Fishway construction costs can be reduced by increasing its bed slope, but this affects the flow field inside the pools, with higher head drops between the basins, as well as turbulence levels and flow velocities, which may affect fish passage. In light of this, a VSF was investigated by 3D numerical simulations to identify the possible effects of the bed slope (using values from 1.67% to 10%) on the flow field and subsequent implications for fish passage. A particular focus was devoted to cyprinind species, but the results can be extended to other species of similar swimming abilities and, therefore, be applicable to multispecies rivers. Flow velocity and turbulence values such as turbulent kinetic energy and Reynolds stresses were analysed from a fish passage perspective in relation to threshold values derived from previous studies. Pool areas where turbulence values are compatible with fish ability and behaviour were quantified. Maps of the location of fish‐friendly zones in the VSF pools were produced and can constitute a reference for practical applications in fishway design. The flow field generated with bed slopes lower than 6.67% is more compatible with fish swimming capabilities, because it exhibits a predominantly 2D behaviour and more suitable hydraulic conditions, whereas at higher slopes, turbulence levels in the pools increase.     

筒装料管道车在不同流量下运动时水力特性研究

为探寻筒装料管道车水力输送的较优输送流量,采用模型试验与理论分析相结合的方法,分析了管道车在不同流量条件下运动时的水力特性。试验结果表明:同一型号的管道车在运动过程中,对某一特定的管道断面而言,流量越大,管道断面中的测压管水头越高;对于同一断面,流量越大,管道车车速也就越大,越早通过这个断面,断面测压管水头也就越早发生变化;流量大小变化不影响管路沿程测压管水头的下降趋势,无论管道车运动到哪个断面,这种整体下降趋势都不会改变,只是下降的幅度不同;而输送效率随流量的增加表现出先增大后减小的趋势。研究成果可为寻求较优的输送流量提供参考。     

Longitudinal spatial variation in ecological conditions in an in‐channel floodplain river system during flow pulses

A field survey was conducted during flow pulses to investigate the longitudinal spatial patterns in water quality, dissolved inorganic and organic matter, phytoplankton, planktonic bacteria, zooplankton, gross primary productivity (GPP) of phytoplankton and planktonic respiration (PR) in channels of the large floodplain system (～124 km in length) of the Macquarie Marshes, south‐eastern Australia. Four river reaches (areas) with distinct hydrogeomorphological characteristics within the distributary zone of the lower Macquarie River were chosen for analysis of abiotic and biotic variables in their in‐stream environments. The results showed marked longitudinal spatial variation in the values within and among the measured environmental variables including such functional aspects as primary productivity and PR. The variables that tended to have increasing values in a downstream direction were conductivity, total nitrogen (TN), total phosphorus (TP), dissolved reactive phosphorus (DRP), dissolved silica, dissolved organic carbon (DOC), dissolved organic nitrogen (DON), dissolved organic phosphorus (DOP), ratio of DOC/DON and counts of planktonic bacteria. Conversely, the values that tended to decrease downstream were the ratios of TN/TP, DIN/DRP, DOC/DOP, DON/DOP and GPP/PR. Variables that had a localized peak(s) were dissolved oxygen, turbidity, dissolved inorganic nitrogen, GPP, PR and counts of cyanobacteria, diatoms, green algae, cryptomonads, protozoans, rotifers, copepods and cladocerans. Overall, two distinct ecological zones were identified within the broader distributary functional process zone (FPZ): these being the upstream zone with relatively high levels of DO, turbidity, diatoms and GPP/PR ratio, and the downstream zone with relatively high levels of nutrients, dissolved organic matter, cyanobacteria, planktonic bacteria, protozoans and cladocerans. The results of this study describe the spatial connectivity of ecological processes related to hydrogeomorphological factors within a FPZ of a riverine ecosystem, and support the predictions of the riverine ecosystem synthesis framework that ecological patterns and processes can be discontinuous on a longitudinal spatial scale. Copyright © 2010 John Wiley & Sons, Ltd.