动态混合絮凝器内絮团粒度分布的研究

实验测定了平直叶轮动态混合絮凝器内絮团粒度的空间分布。结果表明,沿絮凝器半径方向,絮团粒度先是随半径的增大而增大,在达到某一最大值后则转而降低;在絮凝器的轴向,絮团粒度在叶轮上下两侧附近存在极大值。文中分别依据颗粒的离心沉降与径向流动理论以及流体剪切理论解释了絮团粒度的径向分布,从微涡旋理论定性说明了絮团的轴向分布。     

PAC+PAM协同絮凝埃洛石的行为研究

论文采用聚合氯化铝(PAC)和阴离子聚丙烯酰胺(PAM)两种絮凝剂,研究了二者协同絮凝埃洛石的行为,通过浊度,红外光谱和絮团显微结构的观察,分析了二者协同絮凝埃洛石的机制.PAC+ PAM协同作用适宜絮凝条件为:药剂总浓度3.33 kg/t,药剂配比PAC∶ PAM =3∶1,搅拌时间90 s,沉降时间10 min.结果 表明,先加入PAC可压缩埃洛石表面双电层,同时架桥作用产生小絮团;后加入PAM,PAM大分子链条可与多个PAC产生的小絮团和埃洛石连接,生成大絮团,发挥了网捕卷扫作用;PAC与PAM复配使用,有效将二者优点结合,与单独使用情况相比,可以在保证絮凝效果的同时,有效降低药剂用量.     

快速流化床颗粒团絮特征的MP-PIC数值模拟

为了研究快速流化床颗粒的团絮特征,建立了基于多相质点网格法的快速流化床气固多相流三维数理模型,气相场采用大涡湍流模型,通过求解牛顿运动方程得到颗粒相运动信息,气固间相互作用力采用Gidaspow曳力模型,固体间作用力通过计算颗粒应力梯度得到。基于该模型,对三维快速流化床上升管(H=3 m、d=0.1 m)气固流动开展了数值模拟,并与实验进行了校正,研究了在气速工况Ug=5.28 m?s-1下的颗粒(ρp=2650 kg?m-3、dp=250μm)团絮性质,实现了对上升管内颗粒团絮的基本类型(条形团絮、马鞍形团絮、U形团絮)的成功预测,并揭示了不同类型团絮在上升管内形成、发展、聚并直至破碎的演化规律。结果表明,上升管径向颗粒团絮的平均颗粒浓度分布呈现中间低两边高的环核结构,颗粒团絮速度的分布与其相反;随着轴向高度的增加,颗粒团絮的颗粒浓度逐渐降低而速度逐渐增加,但达到一定高度后变化减缓。     

调驱用纳米聚合物微球分散体系流变性评价

纳米聚合物微球粒径呈高斯正态分布。微球颗粒在水中初期分散均匀,水化后微球边缘变模糊,球形度逐渐降低,并局部聚集形成团簇。微球粒径越大,质量浓度越高,分散体系黏度越高。黏度随剪切速率增大而逐渐下降。剪切速率增大过程中微球颗粒分布状态由分散游离变为交叠黏结,最终有序排列。高质量浓度流变剪切具有明显的Weissenberg效应,表现出粘弹性流体特性。矿化度越高,微球分散体系初期黏度越低。剪切后期不同矿化度下分散液黏度保持稳定。高矿化度水中阳离子的存在对微球有吸附絮凝作用。微球分散体系剪切后放置时间越长,黏度呈逐渐回升趋势,有利于微球在地层持久发挥深部调驱液流转向的作用。     

金鸡岩选煤厂提高煤泥回收效率的研究

介绍了金鸡岩选煤厂煤泥水处理系统存在的入洗原煤煤质逐年恶化、煤泥水中的细粒含量增多、处理困难等问题,选用新型有机高分子凝聚剂(8103P)与聚丙烯酰胺(PAM)对煤泥水进行絮凝沉降试验,使煤泥水中的煤泥颗粒絮凝成较大的絮团而快速沉降,达到节能降耗、创效增收的目的。     

壳聚糖对微细粒蛇纹石的分散/絮凝作用

通过沉降试验、吸附量测试和Zeta电位测试,研究壳聚糖对微细粒蛇纹石的分散及絮凝作用,并考察其作用机理.结果表明:蛇纹石的沉降受pH值影响较大,在pH =9时沉降较快.壳聚糖对蛇纹石的絮凝作用受pH影响较大,在pH值为3时,壳聚糖溶解在水中,通过氢键作用吸附在蛇纹石表面,吸附量较低,对微细粒蛇纹石产生分散作用,使其沉降速度降低;pH值为9时,壳聚糖从溶液中析出,沉积在蛇纹石表面,吸附量较大,从而使微细粒蛇纹石形成较大的絮团,沉降速度较快并在底部形成体积较大的沉降体.当沉降体的pH值从9变为3时,沉积在蛇纹石表面的壳聚糖重新溶解,絮凝作用消失,蛇纹石絮团分散,蛇纹石颗粒在自身重力作用下继续沉降,使沉降体体积降低,含水量也降低.     

短程混凝-膜过滤工艺清洗过程中气液两相流对絮体形成的影响

基于数值模拟的方法研究了不同填充密度和不同曝气强度下短程混凝-膜过滤工艺中膜清洗过程反应器内流场特性。结合絮凝动力学理论,引入微涡旋尺度参数来判定影响絮体形成的流场状态,以评估膜清洗过程中曝气强度对絮体形成及膜清洗效果的影响,并用实时图像技术对模拟结果进行验证。研究结果表明,反应器填充密度为7.38%,气水比为15:1时,反应器内平均有效能耗适中,且形成的微涡旋尺度也适中,不会对絮体产生明显的破坏作用,有利于形成较大尺寸的絮体;同时在膜组件附近产生较强的水流剪切速度,使膜面得到有效的清洗。结合实验分析,反应器填充密度为7.38%,气水比为15:1时,反应器内形成的絮体粒径较大且与数值模拟得到的微涡旋尺度相近,上清液UV254和TOC值最低,去除效果最好。     

磷矿酸解料浆与高分子絮凝剂形成的絮团特性研究

用光学连续摄像技术研究了不同絮凝条件下磷矿酸解渣与聚丙烯酰胺形成的絮团特性。实验结果表明酸解料浆与聚丙烯酰胺絮凝剂形成的絮团具有分形几何特征。应用分形理论得到絮团降落速度与絮团孔隙度和絮团密度的关系式。用激光粒度分布仪在线测定了流体力学条件对该体系团强度的影响。在湍流情况下絮团最大平均粒径取决于酸解渣原始平均粒径和体系的能量耗散。较大的絮团破坏主要以裂解为主,在最小的湍流漩涡区也存在相当程度的剥离破坏。试验发现絮团强度随聚合物分子量的增加而提高,对于获得最大平均粒径的稳定絮团存在最佳的絮凝剂加入量。．     

壳聚糖絮凝动力学研究

通过不同情况下 ,壳聚糖絮凝皂土颗粒 ,絮体大小随时间的变化过程来研究絮凝动力学。研究认为水力梯度 G值是影响稳态絮体尺寸的关键因素 ;初始浊度和壳聚糖相对分子质量对稳态絮体尺寸和形成稳态絮体的时间亦有影响     

石油磺酸盐对PAFSi-PAM~+处理钻井废水絮凝作用的影响

通过测定石油磺酸盐(TRS)对絮凝体系下清液透光率、絮体上升速率、滤过速率及絮体形态的变化,研究了TRS对杂化絮凝剂PAFSi-PAM+絮凝作用的影响。结果表明:TRS增加了钻井废水中胶体粒子的Zeta电位,从而增加了絮凝难度。当TRS质量分数超过0.3%时,TRS与PAM+可形成稳定的复合物,絮体上升速率及絮凝体系的滤过速率均高于其他体系,且由于TRS的高分散能力,将导致絮体剥落,使体系的絮凝效果变差。     

发酵液絮凝过程絮凝体微尺度与分离性能

为探索发酵液絮凝分离过程规律以提高分离效率,本文在微观层面上研究发酵液絮凝过程中的剪切力、絮凝体尺度对絮凝体过滤分离效果的影响。以小诺霉素发酵液为研究对象,在絮凝过程中改变絮凝体所受的剪切力,使用激光粒度分析仪在0.02～2000 μm尺度内测定不同剪切力下絮凝体的粒度及粒度分布,并测定絮凝体的过滤速率及沉降速率。实验结果显示：絮凝体的粒度随剪切力的增大而减小,絮凝体的粒度分布宽度随剪切力的增大而增大;絮凝体的沉降分离速率随絮凝体粒度的增大而增大;在适度的剪切力下絮凝体有一适度的粒度及粒度分布宽度和较大的密实度,此时絮凝体的过滤分离速率有一最大值。实验结果表明：絮凝过程中的剪切力显著影响絮凝体的粒度、粒度分布和密实度,从而显著影响絮凝体的过滤速率及沉降速率。     

Flow regime, hydrodynamics, floc size distribution and sludge properties in activated sludge bubble column, air-lift and aerated stirred reactors

This paper presents a comparative study how reactor configuration, sludge loading and air flowrate affect flow regimes, hydrodynamics, floc size distribution and sludge solids-liquid separation properties. Three reactor configurations were studied in bench scale activated sludge bubble column reactor (BCR), air-lift reactor (ALR) and aerated stirred reactor (ASR). The ASR demonstrated the highest capacity of gas holdup and resistance, and homogeneity in flow regimes and shearing forces, resulting in producing large numbers of small and compact flocs. The fluid dynamics in the ALR created regularly directed recirculation forces to enhance the gas holdup and sludge flocculation. The BCR distributed a high turbulent flow regime and non-homogeneity in gas holdup and mixing, and generated large numbers of larger and looser flocs. The sludge size distributions, compressibility and settleability were significantly influenced by the reactor configurations associated with the flow regimes and hydrodynamics.     

Evaluation of flocs resistance and reflocculation capacity using the LDS technique

In a previous paper we have shown the added value of using LDS to monitor flocculation. It can supply, simultaneously, information on flocs size and structure and enlighten flocculation kinetics and mechanisms. In this paper, LDS is applied to study deflocculation and reflocculation processes of precipitated calcium carbonate (PCC) induced by cationic polyacrylamides, when different types of shear forces are applied. LDS can detect the influence of polymer characteristics and concentration as well as of the type of shearing, on flocs resistance and reflocculation degree, which depend on flocs structure and on the type of bonds between particles. As expected, flocs formed by bridging mechanism reflocculate with difficulty while flocs formed by patching reflocculate to a higher degree. Flocs resulting from reflocculation are more compact than the original ones, as assessed by the mass fractal dimension. Reflocculation is also lower when the flocs are submitted to superficial shearing than when they are submitted to sonication. Shearing induced by sonication is sufficient to break down the flocs in many fragments while the increase of pump speed only detaches particles by erosion, at the flocs surface, where bonds are weaker. Results prove that LDS is useful to monitor deflocculation and reflocculation processes and to predict floc resistance under different conditions. Moreover, the whole study demonstrates the benefit of using LDS for a complete evaluation of flocculants performance in the different stages of flocculation: aggregation, stabilization, deflocculation and reflocculation.     

短程混凝-膜过滤工艺清洗过程中气液两相流对絮体形成的影响

基于数值模拟的方法研究了不同填充密度和不同曝气强度下短程混凝-膜过滤工艺中膜清洗过程反应器内流场特性。结合絮凝动力学理论,引入微涡旋尺度参数来判定影响絮体形成的流场状态,以评估膜清洗过程中曝气强度对絮体形成及膜清洗效果的影响,并用实时图像技术对模拟结果进行验证。研究结果表明,反应器填充密度为7.38%,气水比为15：1时,反应器内平均有效能耗适中,且形成的微涡旋尺度也适中,不会对絮体产生明显的破坏作用,有利于形成较大尺寸的絮体;同时在膜组件附近产生较强的水流剪切速度,使膜面得到有效的清洗。结合实验分析,反应器填充密度为7.38%,气水比为15：1时,反应器内形成的絮体粒径较大且与数值模拟得到的微涡旋尺度相近,上清液UV₂₅₄和TOC值最低,去除效果最好。     

Coagulation of Particles Through Rapid Mixing

As is often assumed, rapid mix effectively distributes the dosed coagulant in suspension to promote subsequent flocculation of suspended particles and coagulant molecules. This study determined that the role of rapid mix is considerably more complex than conventionally assumed. Particles in the raw water samples from the Banxing Water Works of Taipei City were coagulated at high shear environment, during which flocs of size 40–70 μm were produced. The produced floc interior was compacted, and residual turbidity and the amount of dissolved natural organic matter (NOM) in suspension were substantially reduced. The subsequent stage of rapid mix slightly reduces floc size, further compacts the floc interior, and expels fine particles and some adsorbed NOM from the flocs. A sudden reduction in shearing rate produced large sized flocs with not so compact structures. Moreover, this action released fine particles from flocs into the suspension and enhanced adsorption of NOM onto solid surfaces.     

Coagulation of Particles Through Rapid Mixing

As is often assumed, rapid mix effectively distributes the dosed coagulant in suspension to promote subsequent flocculation of suspended particles and coagulant molecules. This study determined that the role of rapid mix is considerably more complex than conventionally assumed. Particles in the raw water samples from the Banxing Water Works of Taipei City were coagulated at high shear environment, during which flocs of size 40-70 μm were produced. The produced floc interior was compacted, and residual turbidity and the amount of dissolved natural organic matter (NOM) in suspension were substantially reduced. The subsequent stage of rapid mix slightly reduces floc size, further compacts the floc interior, and expels fine particles and some adsorbed NOM from the flocs. A sudden reduction in shearing rate produced large sized flocs with not so compact structures. Moreover, this action released fine particles from flocs into the suspension and enhanced adsorption of NOM onto solid surfaces.     

Floc Strength Evaluation at Alternative Shearing with Presence of Natural Organic Matters

The effects of natural organic matters (NOM) on Al-floc stability were investigated by on-line probing of changes in floc diameters and interior fractal dimensions at alternative shearing using the small angle light-scattering technique. Fine kaolin particles coagulated with polyaluminum chloride (PACl) formed flocs of size adjusted during subsequent alternative shearing. The presence of humic acid or chitosan reduced or boosted floc formation. Floc breakage is completely irreversible at high humic acid concentrations. Certain master curves for floc size versus time curves were assessed, depending on shearing rate and added organic substances but not on the alternative shearing rates. A two-level floc breakage and reformation scheme was proposed in this study to interpret the observation results.     

辽河油田稀油二元复合驱采出污水絮凝处理研究

对辽河油田稀油二元复合驱采出污水进行絮凝处理。优选了无机、有机絮凝剂,考察了复配絮凝剂效果及其加药方式对絮凝效果的影响,研究了不同絮凝剂产生的絮体形态。结果表明,优选的无机絮凝剂为聚合氯化铝(PAC),有机絮凝剂为阳离子聚丙烯酰胺(CPAM),其絮凝效果随阳离子度的提高而提高。有机絮凝剂投加量对复配絮凝剂的处理效果影响较大。适宜的复配药剂投加量为PAC 300 mg/L、CPAM-1 4 mg/L,处理后污水SS的质量浓度为10.65 mg/L、油的质量浓度为2.43 mg/L、透光率为84.0%,絮体较致密。最好的加药方式为投加完无机絮凝剂后,立即加入有机絮凝剂。不同的絮凝剂形成的絮体形态不同,复配时CPAM-1的投加量越大,絮体越致密。     

Modelling PCC flocculation by bridging mechanism using population balances: Effect of polymer characteristics on flocculation

A population balance model for flocculation of PCC particles with polyelectrolytes of very high molecular weight, medium charge density and different degree of branching is presented. The model considers simultaneously aggregation, breakage and flocs restructuring to describe the PCC flocculation by bridging mechanism. The maximum collision efficiency factor, a parameter related with the fragmentation rate and a time constant for flocs restructuring have been taken as fitting parameters. These fitting parameters are optimized to get the best fit between experimental data obtained by LDS in a previous study and the modelled results. The optimized parameters were correlated with flocculant concentration, flocs structure and polymer branching. The correlations obtained show well the effects of flocculant concentration, flocs structure and polymer structure on the flocculation kinetics and flocs restructuring which are translated in the model parameters. Moreover, the flocs break up due to polymer degradation was introduced in the model by decreasing, with time, the maximum collision efficiency factor. It was shown that this effect can be neglected since the improvement in the results is too small relatively to the high increase of the computational time required to perform the simulation.     

磁絮凝强化技术处理厌氧消化污泥脱水液

为满足后续生物处理单元对固体悬浮物（SS）和铁浓度的进水要求,采用磁絮凝强化技术对厌氧消化污泥脱水液进行预处理。通过正交试验和单因素试验,本文考察了混凝水力条件、聚合氯化铝（PAC）投加量、聚丙烯酰胺（PAM）投加量、磁粉投加量及药剂投加顺序对磁絮凝效果的影响。试验结果表明：磁絮凝强化技术在快搅300r/min（2min）、慢搅100r/min（15min）、静置10min时,依次投加磁粉（40mg/L）、PAC（30mg/L）、PAM（4mg/L）时处理效果最好。在此运行条件下,SS和Fe³⁺去除率分别为97.61%、98.24%、絮凝指数（FI值）取得最大值、zeta电位绝对值最小,絮凝效果最佳。与对照相比,磁絮凝强化技术对SS和Fe³⁺去除率分别可提高3.70%和10.82%,同时絮体最大沉降速度可提高33%。磁絮凝技术处理后的出水不仅可以满足后续生物处理单元对SS和铁浓度的要求,还可以有效提高磁絮凝体的沉降速度,减小沉淀时间,具有较好的实用价值。