往复式隔板絮凝池的优化改进与模拟分析

传统的往复式隔板絮凝池絮凝效率低、絮凝时间长,因而导致絮凝效果不佳。为了更加合理地优化絮凝池流场结构,提高絮凝效果,采用数值模拟的方法,利用Fluent以1∶1比例进行数学建模,并结合絮凝理论和数值模拟结果深入分析其内部流场的水力特性对絮凝效果的影响和存在的问题。随后提出在絮凝池廊道内设置一定数量不同间隙的栅条,结果表明,优化改进后的隔板絮凝池(栅条间隙取80 mm)水流速度和湍动能的水力条件变化都有利于提高絮凝效果。     

Flocculation morphology: effect of particulate shape and coagulant species on flocculation.

Flocculation morphology is a new concept that investigates the morphological characteristics of colloidal particles and coagulants in water during the flocculation process, and the influence that these characteristics have on flocculation process efficiency. This paper is a summary of advances in research on this topic over several years. Morphological characteristics of colloids in natural waters and different kinds of hydrolysed coagulants are investigated, and their effect on colloid stability, flocculation kinetics and efficiency is analysed. It is confirmed that the traditional theory has some deviations in coagulation of nonspherical particles, and these deviations are revised by the flocculation morphology model. Flocculation morphology can not only promote research about flocculation theory, but also instruct the production, application and flocculation control. It can be foreseen that more progress will be made in research and application of flocculation morphology in the near future.     

水翼式叶轮搅拌器在机械絮凝池中的应用

水翼式(hydrofoil)叶轮搅拌器非常适合于竖直轴机械絮凝池中作为絮凝搅拌器使用,并且与传统的桨板式叶轮搅拌器絮凝效果一样.在介绍搅拌器重要参数的基础上,对水翼式叶轮搅拌器的设计选型进行了探讨,阐述了流量系数法的计算方法和过程,深入剖析了设计中要注意的一些问题,并给出了两个典型的应用实例.     

低温低浊水絮凝工艺的数值模拟与响应面优化试验研究

为探究微涡流絮凝工艺处理低温低浊水时,絮凝区流场流态的变化以及水中浊度、CODMn、UV254的最优去除效果,采用CFD数值模拟探究不同流量(絮凝时间)下絮凝区流场流态,确定最佳絮凝时间;应用响应面中Box-Behnken的中心组合设计方法,研究了流量、混凝剂投加量与涡流反应器投配比及其交互作用对微涡流絮凝工艺去除浊度...     

基于计算流体力学的往复式隔板絮凝池流场模拟分析

应用计算流体力学软件FLUENT对往复式隔板絮凝池进行了流场数值模拟分析.通过分析发现,池内的水流变化模拟特征与实际情况相吻合,能够较真实地反映流场内部微观的变化情况,从水力学的角度分析了流场对絮凝效果的影响.同时也可为工程设计人员的设计方案优化提供参考.     

往复隔板絮凝池边壁形状对絮凝反应的影响研究

通过往复隔板絮凝池混凝反应的模型试验 ,对不同边壁条件下的絮凝效果进行了分析比较 ,可知边壁的形状对改善水流结构起着显著的作用。将絮凝池拐角及隔板端面设计为圆弧形 ,可保持所要求的紊流能耗和最佳水力条件 ,为老水厂改造提供了一条有效途径。     

Enhanced flocculation/sedimentation process by a jet mixed separator

This paper deals with the performance of a jet mixed separator (JMS) which has a series of porous plates inserted in the channel perpendicular to a flow. The water passes through holes in the plates, thus creating jets which gently mix the water on itself. Simultaneous flocculation of suspended particles and sedimentation of grown-flocs occur in the JMS, because large-scale eddies in the vertical plane are almost absent in it. The JMS incorporated with inclined tube settlers was applied to the rapid sand filtration system instead of the combination of mechanical flocculator and sedimentation basin. The turbidity of JMS effluent was constantly below I TU at the hydraulic retention time of about 1 hour. The JMS without inclined tube settlers was used as physico-chemical pretreatment process for the rotating biological contactors. The BOD and suspended solids concentration of JMS effluent were around 50 and 40 mg/L, respectively at the hydraulic retention time of 45 min.     

Simulation and system identification of dynamic models for flocculation control

Instrumentation to support advances in particle-fluid separation control have recently become commercially available; however process models, system identification and automatic control laws are still required. This article first describes the derivation and simulation of a dynamic model for the flocculation process based on a population balance approach. This process model contains a poorly modeled function of the coagulant, mixing power, and average particle size. Accurate on-line identification of this function will be critical for the implementation of high performance flocculation control. As an initial step in this direction, this article describes experimental work involving identification of this unknown function across independent controlled experiments. Consistent results partially validate the proposed system model. The ultimate objective is to use detailed particle size distribution measurements and the dynamic models of particle flocculation to analyze and develop control laws for the flocculation process.     

盐度对伊利石不等速沉降絮凝的影响

盐度是影响粘性泥沙絮凝沉降的重要因素之一。将胶体化学中的XDLVO理论引入颗粒沉降三维格子玻尔兹曼模型,模拟黏土矿物质絮凝沉降过程,研究伊利石在不同盐度条件下的不等速絮凝沉降过程。模拟结果表明,伊利石黏结概率随着盐度先增加后保持不变,最佳絮凝盐度在5左右;伊利石絮凝形成的絮团粒径呈现双峰分布,盐度对粒径分布有一定影响。盐水中双电层排斥力受到抑制,起主要作用的是范德华吸引力,使得伊利石颗粒更容易产生絮凝,三维数值模型从细观尺度揭示了盐度对伊利石不等速沉降絮凝的影响机理。     

Towards mechanistic models for activated sludge flocculation under different conditions based on inverse problems

Experimental data of Ca-induced activated sludge flocculation under different conditions of temperature and dissolved oxygen are investigated in order to model the influence of changing physical and chemical factors. However, current kernel structures for collision frequency and efficiency are unable to describe activated sludge flocculation data. Therefore, an earlier developed methodology based on an inverse problem is applied, yielding empirical models, to find out how flocculation is affected by these different environmental conditions. This contribution shows the useful application of inverse problems to improve the understanding of complex aggregation mechanisms.     

黏性泥沙受紊动剪切作用下的絮凝效果研究

我国水库运行一直面临着泥沙淤积的问题,而水动力条件的改变对泥沙的絮凝有莫大的影响,针对此问题,研发了一套絮凝沉降装置,以三峡库区长寿河段泥沙为样本,利用多层震动格栅在圆柱形沉降筒中产生各向同性均匀紊流,结合絮凝沉降观测装置,研究分析紊动剪切作用对黏性泥沙絮凝的影响,并得出了基于试验的最优剪切率。结果表明:紊动对于泥沙颗粒的絮凝有较明显的促进作用,且随泥沙浓度的增大(0. 3~1. 0 g/L),絮凝程度也相应地增加;紊动剪切对于中、大颗粒絮体(0. 048~0. 384 mm)的分布具有较大影响;泥沙颗粒在进入沉降柱后可以在几十分钟内快速完成絮凝,在30 min左右即可观测到最大颗粒絮体,随后颗粒最大粒径逐渐下降直至平衡;随着紊动剪切率的增加,其对于絮凝的作用呈现先促进后抑制的规律。     

涡流絮凝澄清技术在嘉兴某净水厂中的运用

嘉兴某公司净水厂在扩容新建澄清池过程中使用涡流絮凝澄清技术,对<给水排水标准图>中320 m3/h水力循环澄清池S771(八)的内部构造作适当改造:缩短喉管长度,改变第一及第二反应室构造并在反应区加入涡流反应器,沉淀区加设斜管,外形尺寸及结构保持不变.改造后单池处理规模提高到500 m3/h,澄清池出水浊度稳定在3 NTU以下,滤后水浊度小于1 NTU,涡流投资在35元/m3以下.实践表明,涡流絮凝澄清技术具有澄清效率高、出水质量优、适应变化能力强、施工方便等优点.     

Image-pro plus软件在泥沙絮凝体结构特征分析中的应用

利用Image-pro plus图像处理软件,分析研究了絮凝体SEM图像,提取了絮凝体外形尺寸及絮凝体内孔隙直径、孔隙率、孔隙比等特征,分析了这些特征与泥沙浓度及絮凝剂浓度的关系。结果表明:采用Image-pro plus软件处理得到的絮凝体结构特征的变化规律与现有结论基本一致,絮凝体沉速随着絮凝体孔隙比的增大而减小,证明了Image-pro plus软件应用于分析絮凝体SEM图像的可行性。     

基于CATIA的水工金属结构型材库开发与应用

结合水工金属结构专业的特点,将CATIA结构设计模块（SR1）引入到水工金属结构领域,创建了水工金属结构型材库。以某水工平面钢闸门为例,阐述了结构设计模块在水工钢闸门设计中的应用过程。与纯粹的零件设计模块相比,极大地缩短了闸门三维设计的时间,提高了设计效率。可在水工金属结构专业推广应用。     

长江口絮凝机理的试验研究

根据室内模拟试验资料，介绍长江口絮凝体的形态，组成，分析盐度（电解质）对絮凝的影响，同时对絮凝机理进行了阐述。     

温度对黏性泥沙絮凝影响的机理研究

用格子玻耳兹曼方法,引入胶体作用理论(e Xtended Derjaguin-Landau-Verwey-Overbeek theory,XDLVO理论)模拟不同温度下两个黏性泥沙颗粒静水不等速沉降絮凝过程。结果表明,温度升高缩短泥沙絮凝时间,促进絮凝。同时分析了泥沙颗粒的运动轨迹、相对运动速度和颗粒间近距离作用力,探讨温度对泥沙絮凝的影响机理。分析结果认为温度升高一方面减小水体黏性系数,加大泥沙沉速,加快泥沙颗粒相互靠近;另一方面,增大泥沙颗粒表面吸附水膜厚度的同时,也增大泥沙颗粒之间的近距离排斥力,对吸附水膜厚度和排斥力影响的综合结果也促进了絮凝。     

Measurements of the sediment flocculation characteristics in the Three Gorges Reservoir,Yangtze River

The flocculation of fine sediments in the Three Gorges Reservoir (TGR) was confirmed in previous studies, but the flocculation characteristics have yet to be fully clarified. In this study, field measurements were conducted in the TGR to investigate the sediment flocculation characteristics. First, the instantaneous flow velocity and sediment concentration were measured through Acoustic Doppler velocimeter and sediment sampling. Then, the effective settling velocity was calculated based on the sediment diffusion theory to deduce the floc size and flocculation degree. Finally, the influences of particle size, flow velocity, and sediment concentration on flocculation were analyzed. Results showed that flocculation occurred in more than half of the sediments in the TGR, and the maximum flocculation degree was between 10 and 30. Flocculation weakened as particle diameter increased, with the critical particle size being approximately 0.018 mm, meaning that flocculation was unlikely to occur when the particle size exceeded the critical value. As the flow velocity increased, the flocculation degree first increased and then decreased, with the critical flow velocity being approximately 0.7 m/s, but the critical flow velocity increased with an increase in sediment concentration and tended to be a constant. The flocculation degree also increased with increasing sediment concentration and tended to be constant when the sediment concentration exceeded approximately 0.5 kg/m³. The results provide new information on the flocculation characteristics of the TGR and should be useful for understanding and simulating fine sediment transport in the TGR.     

响应曲面法优化絮凝处理印染废水研究

采用响应曲面分析法和中心组合试验设计,对自制无机高分子复合絮凝剂聚硅酸铝铁硼镁(PSAFBM)絮凝处理印染废水进行考察,以废水的pH、絮凝剂投加量为考察因素,以COD(?)、脱色率为指标,分别建立考察因素和指标间的二次多项式响应曲面模型。模型优化结果显示,在投加量0.63g,废水pH为6.1条件下,COD(?),去除率和脱色率分别可达86.15%和96.54%。经过试验验证,其试验值与模型计算值相对误差小于5%,该方法对优化絮凝处理印染废水具有一定指导意义。     

微砂增效结团絮凝技术处理低浊高藻水的中试研究

针对西安市汤峪水库夏季水质特点和处理要求,提出并采用微砂增效结团絮凝工艺对该原水处理进行中试研究.微砂增效结团絮凝技术是将微砂增效与结团絮凝有机组合的新型水处理工艺.试验结果表明,利用微砂增效结团絮凝技术处理汤峪水库低浊高藻水是切实可行的,系统具有运行稳定性高、出水水质好等特点,且处理效率明显高于采用回流污泥的增效澄清技术.微砂增效结团絮凝工艺能够有效降低出水浊度和CODMn;当微砂投量0.5 g/L时的过程控制参数为PAC投量15mg/L,PAM投量0.4 mg/L,机械搅拌转速8 r/min,上升流速达35 m/h时,藻类去除率可达80％,CODMn去除率达40％,浊度可控制在1.5 NTU以下.     

微污染水源水的强化絮凝处理

利用微涡旋控制理论对南方某水厂传统絮凝网格进行了强化絮凝改造。运行结果表明,基于对剪切力与粘性力控制的强化絮凝网格处理微污染水源水具有一定优势:絮凝能耗小,出水矾花密实(分形系数大),矾花粒径大,对应的沉后水浊度降低0.1～0.3 NTU,沉后水、砂滤水藻类和有机物的去除率分别增加2％～5％。