关于周边进水沉淀池设计和配水槽水力计算中几个问题的探讨

沉淀池是给排水工程中常用的处理构筑物，到目前为止，最常用的有竖流式、平流式和辐流式三种类型的沉淀池。随着科学技术的不断进步，各种类型的沉淀池也都有了较大的改进和革新，目的在于提高处理能力和出水水质，同时降低基建投资及处理成本。在辐流式沉淀池中周边进水...     

微旋流沉降器分离效率的准数模型

通过因次分析和实验数据回归建立了新型微旋流沉降器的无因次准数模型。用模拟悬浮液通过改变流体流量?原水浊度?絮凝剂量?沉降器波纹板斜槽的直径进行沉降实验,测定进水流量、絮凝体沉速、进出水及澄清器内各点溢流水的浊度。结果表明:絮凝体沉速对出水浊度的影响最大;流体流速较小时,增大流速出水浊度减小,流速较大时,增大流速出水浊度增大;波纹斜槽直径越小分离效率越高。实验数据回归的分离效率准数模型与实验及工业数据吻合良好。     

高效活性焦在焦化废水处理中的应用

介绍了高效活性焦处理焦化废水的工艺流程。该工艺吸附与絮凝效果好,工艺设计合理,自动化程度高。高效活性焦沉淀池出水比二沉池出水COD去除率提高56.2%,出水澄清,无SS存在。     

用HYDRONET高效气浮技术替代市政污水厂二沉池的试验研究

在活性污泥法中,二沉池占地面积可观。利用悬浮一附着型纤毛填料技术加瑞士高效气浮技术HYDRONET和某市政污水处理厂卡鲁赛尔氧化沟后的辐流式二沉池的沉淀效果的对比试验,可知出水SS小于2mg／L,优于同期该污水处理厂二沉池出水,得出该高效工艺组台可以替代市政污水处理厂二沉池的结论,并可节省土地。     

斜管沉淀池的改造实例

文章通过实例,对飘合纸业回用水处理系统斜管沉淀池絮凝过程的絮凝池(一般常称反应池)和沉淀区进水方式进行改造;经改造后的处理效率比改造前的沉淀效率提高将近一倍;印证了絮凝池的合理设计和沉淀区的合理布水进水在斜管沉淀池中的重要地位;在实际设计中,应注意对G值的合理分配,避免在絮凝体形成之后,因水流的过度搅动而导致絮凝体的破裂。     

二段生物接触氧化法处理生活污水的实验研究

通过对二段生物接触氧化法处理生活污水的中试研究,发现了适合该工艺方法的新型组合填料。实验结果表明,在水力停留时间为35min（其中一氧池15min,二氧池20min）,接触沉淀池上升流速一沉池为6m/h,二沉池为5m/h,水气比为1：5时效果最佳,COD去除率达88.2%,SS去除率达94%～97%,NH3-N去除率为40%,并且具有很强的耐冲击负荷能力。     

高效沉淀池在污水处理厂提标中的应用实例

本文介绍了高效沉淀池的工艺流程及技术特点,在常规混凝沉淀工艺中投加微砂、重介质等,增加混凝絮体结构重量,加快絮体的沉降速度,去除生化二沉池出水中含有的TP、SS。结合工程应用实例,表明该工艺运行稳定可靠,出水各项指标满足处理标准,运行成本较低,适合于城市污水厂提标改造推广应用。     

二沉池设计和运行中应注意问题的探讨

为了使设计的二次沉淀池具有更高的效率,通过理论和实践的研究,分析了影响二次沉淀池工作性能的多方面因素对二次沉淀池设计和运行中应注意的问题进行了探讨。活性污泥的沉降性能影响二次沉淀池的工作性能,有许多因素,如微生物絮凝性能及絮凝沉降影响活性污泥的沉降性能。二次沉淀池的设计和运行中的关键是要消除沉淀池的厌氧状态。     

不同水处理工艺的混凝效果比较

该文以宁夏宁东地区黄河水为研究对象,考察了不同混凝条件（常规混凝沉淀池、微涡旋混凝沉淀池、反冲洗水回流沉淀池）下三种水处理工艺对混凝效能的影响。结果表明微涡旋改造有助于提高絮凝池的混凝效果,絮体的沉降性得到改善,“跑矾”现象得到缓解,絮体颗粒数目较折板絮凝池减少,沉淀池出水浊度明显降低;滤池反冲洗水回流技术可以有效地提高浊度的去除率以及改善絮体的沉降性能,且絮体颗粒数目较微涡旋絮凝池有明显减少,说明增加水体中颗粒数目可以有效地提高混凝效果;由分形维数的数据可以看出,微涡旋改造和反冲洗水回流可以明显提高絮体的分形维数,改善了絮体的沉降性。     

应用微机建立玻璃窑炉池壁温度场模型

玻璃液面附近的池壁,是决定窑体寿命的关键部位.池壁的传热过程以二维稳态传热考虑比较实际情况.采用数学模拟的方法,建立熔窑池壁砖内部的温度场模型.结合池壁温度模型的建立探讨生产环节中池壁保护措施的理论依据.     

含细长颗粒的洗涤冷却室内的多相分布特性

采用改进的直接取样法,在按几何尺寸缩小的工业气化炉洗涤冷却室冷模装置内,同时测量不同操作条件下的轴径向局部固含率和气含率,对细长颗粒在洗涤冷却室内的多相分布特性进行研究。结果表明：以下降管出口截面为界,洗涤冷却室可分为上部气液固混合区和下部固液流动区,其中上部区域由下降管出口区、破泡板作用区和气垫层区组成,下部区域由气相湍动作用区、回流区和二次流动区组成;在颗粒阻碍效应减速沉降和团聚效应加速沉降的共同作用下,轴向固含率呈现波动分布;环隙气速、固相体积分数和长径比的增加均会增强床层的湍动,促进气体的径向扩散;操作条件的改变使颗粒的漂移速度发生改变,径向固含率分布出现波动;在气相扰动和回流作用下,二次流动区呈现环状流动,流体和颗粒的"壁面效应"使该区域的固含率呈现中心高边壁低的特点。     

用LDA研究搅拌釜内的流场

利用ＤＡＮＴＥＣ二维激光多谱勒测速仪对ＤＴ叶轮和ＰＴＵ叶轮的搅拌槽进行了流场测试，获得了不同几何参数的叶轮在不同工况下的二维时均速度场和湍流强度场，尤其是ＰＴＵ浆的内锥边界。为进一步研究搅拌器的流动特性、开发新型桨叶叶轮提供了可靠的实验依据。     

Influence of flow field on sedimentation efficiency in a circular settling tank with peripheral inflow and central effluent

The paper presents an experimental study of suspension flow patterns and velocity field inside a circular settling tank with continuous operation. Research was focused on the impact of a specific flow pattern on the sedimentation efficiency of the prototype settling tank. The latter differed from a common circular settling tank in that it was peripherally fed and had the central draw-off. Experiment was carried out on a settling tank section made of plexiglass and represented a radial slice of a prototype settling tank. The flow field and local suspension concentration was determined by computer-aided visualization. Sedimentation efficiency was assessed relatively by comparison of the amount of settled particles (sludge height measurements) between different types of flow in a certain time period of the settling tank operation. Results showed that there were two types of flow in the settling tank that were initiated by a horizontal or vertical inflow from the distribution ring. The type of inflow (horizontal or vertical) was a function of the suspension height in the settling tank. Significant differences in sedimentation efficiency were observed between both types of flow, particularly at lower inlet suspension concentrations. Horizontal inflow proved to be less efficient in terms of settling.     

90°弯管内湍流流动的数值模拟

进行了90°弯管内湍流流动的数值模拟实验。结果表明,切向速度在开始旋转阶段内侧的速度增大、压力减小,外侧速度降低、压力增大;当转过60°截面后,外侧的速度增大、压力减小,内侧速度降低、压力增大。弯管内流体旋转产生的离心力导致压力分布的变化,使得弯管内流体产生垂直于主流切向速度的轴向速度和径向速度,形成了二次流。90°弯管流场是主流切向速度与二次流的叠加,呈现出复杂的三维流动特性。     

黄磷受磷槽两相流场数值模拟

以计算流体力学（CFD）技术为基础,对受磷槽内黄磷沉淀及液液两相流动进行数值模拟。模拟结果表明,受磷槽内水相流动状态十分复杂,且流动趋势不受进口流量的影响。黄磷累积量随进口量改变而改变,但黄磷流动速度变化较小。欧拉多相流及k-ε湍流模型能够较好地描述受磷槽内黄磷分布状态及流体流动状态,模拟结果具有较高的可靠性。     

Rushton涡轮搅拌槽内流场特性及颗粒运动行为数值模拟

基于计算流体动力学（CFD）方法,采用大涡模拟（LES）和拉格朗日颗粒追踪技术计算了Rushton涡轮搅拌槽内流场特性及三种St颗粒的运动行为。平均流场（切向速度、轴向速度和径向速度）、颗粒速度及浓度分布方面与实验值的吻合度较好,验证了数值模拟的可靠性。结果表明,搅拌流场及颗粒运动均呈现循环流特性,当转速N=313r/min不变时,St=0.24的小颗粒几乎实现了均匀分布;而St=37.3的大颗粒与流体的跟随性较差,底部沉积率较高,容器顶部会出现一定的颗粒空白区。叶轮附近产生一系列的湍流涡结构,并且由于剧烈的颗粒-壁面碰撞,该位置颗粒拟温度最高;小颗粒（St=0.24）的运移主要受叶片后方尾涡的控制,均匀分布在低涡量区;而大颗粒（St=37.3）由于具有较大的惯性,运动不再由涡主导,很快被叶轮甩向边壁,穿过了尾涡所形成的高涡量区,故而叶轮对附近大颗粒的搅拌效果较差。     

Numerical simulation of secondary sedimentation tank for urban wastewater

Secondary sedimentation tanks, which are used widely in wastewater treatment, require optimization to improve wastewater treatment efficiency. The flow dynamics is an important parameter for the design of reactors. However, very little literature deals with the flow in secondary sedimentation tanks. Therefore, the flow dynamics in a secondary sedimentation tank is studied in this paper. The solid–liquid two-phase turbulent flow in the tank is modeled with the three-dimensional two-fluid model. Using computational fluid dynamics (CFD), the velocity profile and distribution of solid concentration are given. The use of different baffles in the same tank is also simulated. With the inclusion of the baffle, the distribution of the solid concentration differs greatly. The significant effects of the baffle height and baffle location on the distribution of solid concentrations are also discussed. These results provide useful information for the design of secondary sedimentation tanks.     

轴流桨搅拌槽内轴向流动速度的研究

为研究轴流桨搅拌槽内轴向速度的分布,在直径为300 mm的平底圆筒搅拌槽内,采用相位多普勒粒子分析仪(PDPA)对轴流式搅拌器主流区的流场进行测量。在不同转速和离底间隙条件下,对挡板前轴向时均速度在径向和轴向的分布进行分析和研究,采用壁面射流理论,建立搅拌槽内壁面射流流动模型,揭示轴向流动特性。结果表明:轴向速度沿径向的分布具有相似性;轴向最大速度沿轴向衰减;轴向流边界沿轴向线性扩展。研究结果有助于进一步了解搅拌槽内部流动特性,为固-液悬浮操作、过程放大和搅拌设备的优化设计提供理论依据。     

竖直窄通道充分发展段液固流动特性的数值模拟

采用欧拉-欧拉双流体模型,基于水-玻璃珠体系,对长×宽×高尺寸为240 mm×12 mm×1800 mm的竖直窄通道充分发展段内液固两相流动特性进行了数值模拟。结果表明,沿窄通道竖直方向0.7 m以上液固两相流动进入充分发展阶段,在充分发展阶段的窄通道截面上,狭长方向与狭窄方向各位置颗粒速度及浓度均呈中心区域高、贴近边壁区域低的分布趋势;随着入口液速提高,截面各位置颗粒速度均提高,而颗粒浓度在流道中心区域降低,在贴近壁面区域升高;随着初始固相体积分数增加,截面各位置颗粒浓度均提高,而颗粒速度在流道中心区域略有降低,在贴近壁面区域略有升高;在窄通道截面狭长方向两端靠近三边壁影响的区域存在颗粒增浓效应,在截面狭窄方向颗粒速度和浓度分布梯度较大的区域无量纲占比随着入口液速的提高而提高,随着初始固相体积分数的提高而减小。     

Flotation efficiency of activated sludge flocs using population balance model in dissolved air flotation

The activated sludge process is one of the most frequently used processes for biological wastewater treatment. Conventional gravity sedimentation (CGS), which is widely used as a secondary clarifier in activated sludge processes, has a routine problem due to floating tendency, called bulking, caused by filamentous microorganisms. Dissolved air flotation (DAF) has been applied as potential alternative to CGS as a secondary clarifier. A series of experiments were performed to measure physico-chemical characteristics and removal efficiency of activated sludge flocs. The removal efficiency of flocs corresponding in lag and exponential growth phases was lower, while that of flocs both in stationary and endogenous phases considerably increased. The rise velocity of floc/bubble agglomerates was calculated by using a population balance (PB) model explaining the distribution of floc/bubble agglomerates. The experimental results of flotation efficiency showed a similar tendency with the results predicted by PB model for the rise velocity and distribution of floc/bubble agglomerates. It was found from our study that the DAF process was very effective as a secondary clarifier in the activated sludge process.