排泥水处理技术在闵行一水厂的应用

通过对污泥沉降特性研究 ,闵行一水厂排泥水处理采用收集、浓缩、平衡、投加聚丙烯酰胺 (PAM )、离心机固液分离的工艺流程。浓缩池上清液能达标排放 ,离心机分离水的泥饼含固率≥4 0 % ,PAM加注率 0 8～ 1 5kg/t干泥。研究表明 ,该工艺可作为黄浦江水系水厂排泥水处理工艺设计依据     

月浦水厂排泥水浓缩处理工艺初步研究

对上海市月浦水厂的沉淀池排泥水进行浓缩工艺研究 ,旨在为今后建设给水厂排泥水浓缩处理设施提供设计和运行的必要基础资料。试验结果表明 ,斜板浓缩池对给水厂排泥水可以产生良好的浓缩效果。浓缩后的泥水含固率 >3% ,上清液SS <15 0mg/L。     

天津纪庄子再生水厂泥渣回流强化混凝沉淀工艺技术研究

通过对天津纪庄子再生水厂原水(城市二级出水)进行泥渣回流强化混凝试验研究,证明回流泥渣量在100～300mg/L时效果较好;当泥渣回流后,PAC投药量明显减少,只需5mg/L,基本能达到不加泥渣时投药量15mg/L的效果,节省了67%的投药量。通过正交试验确定混凝沉淀工艺的最佳混凝条件:快速搅拌45s,搅拌速率150r/min;慢速搅拌20min,搅拌速率50r/min。并且污泥浓度为10000～20000mg/L时的污泥回流才能得到比较好的处理效果。     

南洲水厂排泥水处理工艺的研究与设计

通过对排泥水进行沉降试验,得到了南洲水厂排泥水处理系统设计的基本数据.供水量为100万m3/d的南洲水厂排泥水处理系统工艺流程为:排泥水调节、浓缩、平衡、离心机脱水.该系统在调试运行期间,各工艺单元均能按照设计要求正常工作,脱水后的污泥含固率达到36.3%～39.2%,取得较好的处理效果.     

给水厂排泥水浓缩试验研究

给水厂排泥水的小试和现场中试研究结果表明,投加PAM后快速搅拌排泥水(不小于300r/min)30s左右,矾花出现早,絮凝颗粒大,泥水分离效果好。斜板浓缩池的斜板间距5～8.6cm对出水效果的影响不显著,浓缩效果相差不大。最佳斜板间距为5.5～8cm。当投加PAM出水效果不佳时采用快速机械搅拌装置能较好地提高排泥水的浓缩效果。     

苏州某自来水厂排泥水处理系统运行优化试验研究

为提升自来水厂排泥水处理系统运行效率,降低水厂耗水率,开展排泥水预处理试验和浓缩池动态模型试验.结果表明:与预处理前相比,投加0.3 mg/L阳离子型PAM,可以使排泥水中粒径小于5μm的颗粒占比减少22％,粒径大于10μm的颗粒占比提高110％,颗粒沉降速率提高20％,上清液浊度下降75％.根据浓缩池动态模型试验结果...     

河北应急水源工艺适应性研究与工艺优化

南水北调的应急工程是从河北四水库调水进京,为了保证净水厂运行稳定,进行了适应性研究,并采用层次优化法对中试工艺进行选优。结果表明:第九水厂工艺运行方案为采用粉末活性炭预处理(20mg/L),混凝剂投加量为20～25mg/L;当原水藻类较高时可采用"氯+粉末活性炭"联合预处理方式;在剑水蚤数量较多时,建议砂滤池和炭池的反冲洗水不回收。第三水厂、田村山水厂采用混凝—沉淀—过滤—O3—炭池工艺,主臭氧投加量为0.5～1.5mg/L,混凝剂投加量为20～25mg/L。剑水蚤数量较少时,混凝沉淀能够将其去除,或通过主臭氧将剑水蚤杀死去除。在调水过程中,应跟踪原水MIB的变化,并加强活性炭出水的臭味检测,适时调整工艺运行参数。     

临江水厂排泥水处理系统设计

为减少临江水厂自身运行给水体造成的污染,建设排泥水处理系统,将沉淀池排泥水及滤池反冲洗水统一收集后,通过调节、浓缩、机械脱水,提高污泥含固率,使排泥水处理后达标排放。临江水厂二期采用高速重力斜板澄清池工艺,由于需要加细砂,砂的漏失增加了日产干污泥量。详细介绍了工程方案的选择和设计参数,并指出了一些设计中值得探讨的问题。     

粉末活性炭应急处理原水静态模拟试验研究

采用静态模拟试验,研究了粉末活性炭应急投加技术中存在的碳种优选、最佳投加量和投加点确定等问题。结果表明,投加粉末活性炭作为头部原水水质变化的应急处理手段是完全可行的,能够保证给水厂的供水安全;PICA煤质碳为粉末活性炭应急处理原水的最佳碳种;结合UV254、CODMn和色度三项指标以及给水厂的实际情况得出,吸水井处为粉末活性炭应急投加的最佳点;在水质急剧变化时,粉末活性炭投量为20～30mg/L是适宜的,其中UV254的去除率净增加20%左右,CODMn的去除率净提高10%左右;当水质极端变差时可考虑将粉末活性炭的投加量增加至50mg/L。     

长沙市第八水厂排泥水脱水工艺设计

长沙市第八水厂排泥水处理工程包括第八水厂和第三水厂(总规模80万m3/d)的排泥水处理,处理流程为排泥→浓缩→贮泥→脱水。其脱水工艺具有不加药,处理后泥饼含固率≥45%,卸泥方便,自动化程度高等特点。介绍了不加药脱水系统主要处理单元设计、设备选型、运行步骤、工艺特点等。     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。