【作者】 李浩宇；

【导师】 南军；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2014， 博士

【摘要】 常规给水处理的核心操作单元为絮凝、沉淀和过滤，其中絮凝常作为三个核心单元中的第一个单元。在絮凝单元中，所形成絮体的粒度、有效密度和结构强度等性质，对后续两个单元的运行效能，例如沉后水水质、滤后水水质和滤池反洗周期等，都具有较大的影响。因此，絮凝工艺的关键在于能否形成良好的絮体。絮体的团聚是逐步渐进的过程，即絮凝初始时存在大量微小絮体，由微小絮体凝聚成小絮体，再凝聚成中等絮体，最后成长为大絮体。其中，小絮体成长为中等絮体的阶段作为絮体成长过程中的初始阶段具有重要的研究意义，在本文中，这一阶段被称为初级絮凝阶段。为了研究初级絮凝阶段的特征，进行了大量絮凝-静沉-快速过滤实验，以聚合氯化铝为絮凝剂，高岭土和腐殖酸的混合悬浊液为原水，通过非连续流给水处理在线监测系统，监测絮凝-静沉-快速过滤过程中水中的浊度、颗粒数量和粒度分布、滤池指定位置的压力。所实现的初级絮凝阶段的表征，包括划分方法、颗粒分布特征变化规律、形态变化规律、定义、影响因素，以及与后续处理工艺间的关系等。并研究了初级絮凝阶段的强化方法和机制，这些成果对絮凝理论和给水处理工艺优化控制的研究具有重要意义。首先，分析了絮凝-沉淀-过滤过程中颗粒分布特征随絮凝时间变化规律，以表征各单元运行效能为目的，建立了常规给水处理工艺过程颗粒分布检测方法，得到如下结论：应用沉后水浊度和2~5μm颗粒数量诊断絮凝-沉淀工艺固液分离效果，应用沉淀初期粒度分形维数下降速度v诊断絮凝出水絮体沉降性能，应用RSS0.5诊断滤后水水质稳定性，应用滤层水头损失上升速率诊断滤层水力参数，各参数间均具有较好的相关性(R2>0.9)。其次，通过对絮凝过程中颗粒分布特征随絮凝时间变化规律的分析，研究了絮凝过程的分段方法、定义和特征。研究结果表明：粒度分形维数适合作为絮凝过程分段的依据，并通过分析其一阶导数随絮凝时间变化规律，将絮凝过程分为准备阶段、初级絮凝阶段、成长阶段和稳定阶段四个部分。并提出了初级絮凝阶段的定义和分析了其特征，找出了表征初级絮凝阶段絮体变化的方法：应用KaG、‘’和Dfg综合评价。并以前面得到的常规给水处理工艺过程颗粒分布检测方法为基础，定量分析了初级絮凝阶段对给水处理工艺中各单元的影响，研究了初级絮凝阶段对给水工艺各单元的影响，实验结果表明初级絮凝阶段絮凝速度每增加1%，絮凝效率增加1.7%，沉淀速度增加4.2%，出水水质稳定性增加0.85%，滤层水头损失增长速度减少0.17%，即初级絮凝阶段的任何变化在后续处理单元都能得到体现和放大的结论，为水厂生产控制及水厂自控研究提供了新的方法。之后建立起加入时间参数的二维DLA模型，模拟研究了絮凝过程中絮体形态随时间变化规律，动力学参数对初级絮凝阶段形成絮体的形态的影响，初级絮凝阶段絮体形态对絮凝出水絮体形态的影响，并在前人研究的基础上改进了絮体分步成长模型，并对模型进行分析计算。研究结果表明：絮体在成长过程中会沿某一优势方向优先生长。初级絮凝阶段形成的絮体具有“活性点”(2-4个)，在成长阶段絮体只会在活性点上成长，并根据活性点的不同成长成不同形态的絮体。絮体有效密度只与初级絮凝阶段形成絮体的有效密度、粒径和活性点数量相关。最后，以前面的研究为基础，提出初级絮凝阶段的强化控制方法，分析了强化方法对初级絮凝阶段的影响，并通过考察沉淀和过滤阶段的运行效能，推断絮凝出水中絮体的沉降性能和粘附性能等性质，最终研究得到了初级絮凝阶段强化控制机制，为实际中强化絮凝工艺的建设、管理和研究提供了新的理论基础。更多还原

【Abstract】 The traditional water treatments mainly contain three units, flocculation, sedimentation and filtration, with flocculation always being the first step of these three units. In the process of flocculation, the characteristics of the flocs, such as the floc size, density and structure strength, have great effects on water quality of the sedimentation outlet and the filter outlet,the period of filter backwash cycle, and other operating parameters. Therefore, the key of flocculation is forming easily-settled flocs in the process. The flocs forming process starts with the small colloidal particles. They aggregate to small flocs, then medium flocs, finally big flocs. The stage of small flocs growing into medium flocs, being defined as the primary flocculation stage in this study, has great research significance.For learning the characteristics of the primary flocculation stage, a series of flocculation-sedimentation-rapid filtration experiments have been finished, with PACL being coagulatant, and the suspension of koalin and fluvic acid being the initial water. Through non continuous online monitoring system of water treatment, water turbidity, particle number and size distribution, the pressure of the specified location in filter were monitored. The characteristics of the primary flocculation stage, got knowledge from this study, include segmentation, the law of particle distribution characteristics, its defination effect factors, and the relation with the subsequence treatment units, diagnosis method of water in the process of each unit and the whole process, control mechanism on the subsequent process of primary flocculation stage, the strengthening mechanism of primary flocculation. These results are of major importance on the research of flocculation theory and optimization control in waterworks.First, the law of particle distribution characteristics changing with time in flocculation-sedimentation filtration process, was studied. The method of detecting particle distribution in traditional water treatment process was established, in order to quantify the efficiency of each unit. This method consists of applying water turbidity and2~5μm particle number to diagnosing flocculation-sedimentation process of solid-liquid separation effect, applying precipitation initial fractal dimension decreased rate of v to diagnosing flocculation floc settling properties, applying RSS0.5to diagnosing filtered water quality stability, applying filter head loss rate of rise to diagnosing filter hydraulic parameters. There is a good relationship between these factors (R2>0.9).Secondly, through analyzing the law of partical distribution characteristics changing with time in flocculation process, the segmentation，defination and characteristics of flocculation were studied. As the results shown, the fractal dimension of particle flocculation process could be used as the basis of flocculation process segmentation. Through the analysis of its derivative rule with the flocculation time changes, the flocculation process is divided into four stages, preparation stage, primary-flocculation stage, growth stage and stable stage. And then the definition of primary-flocculation stage was given,and its characteristics were studied by application of KaG,‘’ and Dfg comprehensive evaluation. Through the quantitative analysis of primary flocculation stage effects on each unit of water supply process, the mechanism of primary flocculation stage dominating the water supply process unit was obtained, which could provide a new method for the study of production control and automatic control of waterworks waterworks. The result shows that when flocculation speed increase1%, flocculation efficiency increase1.7%, settling properties increase4.2%, filtered water quality stability increas0.85%, and filter hydraulic parameters increas0.17%.Thirdly, two-dimensional DLA model with time parameters was set up, and used to simulate and study the floc morphologial rules with time, the effect of floc morphology kinetic parameters on the floc forming of primary flocculation stage, and the effect of floc morphology of primary flocculation stage on that of floccutation outlet. On the basis of other previous research, floc step growth model was improved, and the new model was uesd to analyze and caculate.The results shows that the floc will grow on one certain direction prior to the other ones; the flocs forming in primary flocculation stage have ‘active site’(2-4in one core); in the growth stage, the flocs will only grow at the active site, and according to different active sites grow into different patterns of flocs; the effective density of flocs could alone be effected by the effective density, particle size and quantity of active site of flocs forming in primary flocculation stage.Above all, strengthening control method of primary flocculation stage was established, whose effect on primary flocculation stage was alse studied. Through investigating the efficiency of sedimentation and filtration, the settling and adhesion properties of flocs in flocculation outlet were infered. Finally, the mechanism of primary flocculation stage strengthening control was found, which could become the theoretical basis of construction, management and research of strengthening flocculation in practice..更多还原