改性壳聚糖强化混凝处理低温氨氮污染水源水研究

针对严寒地区传统常规工艺难以处理低温条件下水源水中氨氮超标的问题,采用实验室自制改性壳聚糖锌(CTS-Zn)强化聚氯化铝(PAC)混凝工艺对低温低浊氨氮污染水源水的处理效果进行研究。试验以辽河流域水源为研究对象,采用响应面试验分析设计软件(BOX-Behnken Design),考察了改性壳聚糖锌与聚氯化铝在低温条件下对氨氮、浊度、UV254去除效果最佳的投加量与投加方式,并且进行了改性壳聚糖锌强化聚氯化铝处理反应机理分析。试验结果表明,在温度为4℃时,改性壳聚糖锌可强化聚氯化铝的混凝效果,最佳投加工艺为同时投加0.3mg/L的CTS-Zn与20mg/L的PAC,处理后对原水中的氨氮、浊度、UV_(254)的去除率分别为30.02%、78%、60.8%,比相同条件下单独投加PAC工艺有明显的水质改善效果。该研究成果可为严寒地区水厂工艺提标改造提供技术支持。     

粉末活性炭去除原水中阿特拉津突发污染的研究

利用中试装置研究了水源水阿特拉津突发污染的应急处理措施.试验结果表明:常规工艺不能有效去除原水中的阿特拉津,投加粉末活性炭(PAC)可有效去除阿特拉津,确保出水达到水质标准的要求;PAC投量为50 mg/L时,可使初始浓度为200 μg/L的阿特拉津降低到2 μg/L以下;KMnO4与PAC联用的去除效果比单独使用PAC略有改善但并不显著,预氯化则会降低PAC对阿特拉津和UV254的去除率.     

处理高氨氮和高有机物原水的混凝剂选择试验

以受高氨氮、高有机物污染的淀浦河原水为对象，通过混凝沉淀烧杯试验进行了硫酸铝（AS）、聚合氯化铝（PAC）混凝剂使用效果的对比性研究。比较了两者均浊度、色度、UV254、耗氧量的去除效果。研究表明，硫酸铝和聚合氯化铝的去浊最佳投加量分别为45mg／L和30mg／L．在此投加量下，剩余浊度分别降到1．5NTU和1．0NTU以下，UV254去除率均为13．3％，耗氧量去除率分别为33％和35％；当硫酸铝投加量为60mg／L，聚合氯化铝投加量为40mg／L时，色度去除效果最佳，去除率分别为36％和45％。采用最佳投加量时，每吨水使用混凝剂单位成本分别为0．0342元（硫酸铝），0．0456元（聚合氯化铝）。通过技术和经济成本核算结果，认为聚合氯化铝混凝剂更适用于淀浦河原水达到强化混凝效果。     

PPC预氧化和超滤协同处理引黄水库高藻水

采用高锰酸盐复合药剂(PPC)预氧化—混凝—沉淀—超滤组合工艺处理黄河下游引黄水库夏秋季节高藻水。工艺优化试验结果表明:当处理高藻水时,聚氯化铝最佳投加量为4mg/L,PPC最佳投加量为0.6mg/L。进行了混凝—沉淀—超滤和PPC预氧化—混凝—沉淀—超滤工艺中试比较,结果表明:两种工艺均能将出水浊度控制在0.1NTU以下;投加0.6mg/LPPC能使组合工艺对原水UV254和藻类的平均去除率分别提高10%和28%。将PPC预氧化技术和超滤技术联用,具有协同除污染作用,降低进入膜表面的污染负荷,缓解膜污染。     

载粉末活性炭过滤处理微污染原水的试验研究

载粉末活性炭(PAC)过滤集PAC吸附与过滤于一体,能够应用于微污染原水处理。配水试验结果表明:粒径为1.25-2.5mm,厚度为1000mm的聚苯乙烯滤料层能够用于载PAC过滤。影响过滤效果的主要因素为PAC载量和混凝剂投加量,当混凝剂T3010和聚氯化铝的投加量分别为0.09mg/L和2.5mg/L,PAC载量为2-3g/L滤料时,载PAC过滤处理浊度为20-40NTU的微污染原水的效果达到最佳,对CODMn和浊度都具有很好的去除效果。Z河水作为原水的试验结果表明:载PAC过滤对河水浊度、UV254、CODMn的去除率分别为97%-97.9%、50.9%-63.4%、68.5%-71.4%。     

含腐殖酸低浊原水的改性凹土强化混凝效果分析和参数确定

研究了改性凹土联合聚氯化铝强化混凝耦合去除浊度和腐殖酸的效果。试验原水条件为腐殖酸浓度10mg/L,浊度为(30±1)NTU。采用静态混凝搅拌试验,考察了聚氯化铝和改性凹土的混凝沉淀时间、复配投加量、pH、投加顺序、搅拌速率等工艺参数对腐殖酸和浊度耦合去除效果的影响。结果表明,在强化混凝中,当聚氯化铝投加量为15mg/L,改性凹土投加量为30mg/L,沉淀时间30min,pH=7时,腐殖酸和浊度的同步去除率分别达到95.5%和96.8%,对比单投加聚氯化铝混凝工艺,聚氯化铝投加量可降低25%,并减少沉降时间。     

采用活性炭强化常规处理原水突发油类污染的研究

中试研究表明,常规处理(混凝—沉淀—过滤)可以将含油约为10mg/L的原水处理达标,并且除油率不受混凝剂投加量的影响。油污染浓度为7.2～18mg/L的原水经混凝沉淀去除的效率基本相同。20mg/L的油污染仅通过常规处理无法达标,需采用投加粉末活性炭(PAC)的强化混凝或颗粒活性炭(GAC)的强化过滤,即投加40mg/L的PAC,或在过滤阶段铺40cmGAC层的炭砂滤柱。KMnO4和Cl2的预氧化对除油效果无影响。     

粉末活性炭一混凝联用工艺强化去除毒死蜱试验研究

针对受毒死蜱污染的水源水,通过小试研究了粉末活性炭(PAC)-混凝联用工艺对毒死蜱的去除效果.结果表明混凝工艺对毒死蜱具有一定的去除效果,但当原水中毒死蜱浓度较高时,混凝后毒死蜱浓度高于《生活饮用水卫生标准》 (GB 5749-2006) 30 μg/L的限值,因此为使出水达标还需增加PAC吸附处理措施;针对原水中不同初始浓度的毒死蜱(超标5～50倍),调节PAC投量(10～60mg/L),吸附30 min后,再投加30mg/L聚氯化铝,经PAC-混凝联用工艺处理后出水中毒死蜱浓度小于30 μg/L,满足《生活饮用水卫生标准》要求.PAC-混凝联用工艺可以作为水源水突发毒死蜱污染时的应急处理措施.     

天津渤海湾海水淡化预处理工艺的试验研究

针对渤海湾海水低温低浊、有机物、胶体物质、悬浮物以及细菌等指标较其他海域高的特点,采用"强化混凝—O3/UV消毒"作为海水淡化蒸馏法工艺的预处理工艺,当FeCl3、聚丙烯酰胺(PAM)和聚氯化铝(PAC)的投加量分别为4mg/L、0.3mg/L和0.5mg/L,反应温度为15℃,O3投加量为2.4mg/L,UV辐射剂量为10W/L,UV/O3的接触时间为10min时,原水的浊度、CODMn、UV254及细菌去除率分别为96%、40%、19%和99.91%。经核算,该工艺的单位生产成本为0.782元/m3,单位经营成本为0.411元/m3。     

粉末活牲炭回流技术去除原水中氨氮的研究

将含粉末活性炭(PAC)的沉淀池排泥水回流至原水进水处,延长PAC在系统中的停留时间,考察系统对氨氮、有机物和浊度的去除效果及去除氨氮的影响因素.结果表明,在温度为21～25℃,投炭量为50 mg/L条件下,系统第7～8天运行稳定,对氨氮、UV254和CODMn的去除率分别为40%、45%和60%左右,出水浊度在1 NTU左右,活性炭泥的生物量为130 nmolP/g左右.当活性炭泥回流比为6%,原水CODMn不超过10 mg/L,Ph为7～8,浊度不超过180 NTU时,对氨氮去除效果最好,为40%～50%,可应对原水氨氮浓度小于1 mg/L的情况.     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

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。     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

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。     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.     

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.     

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.