铁盐絮凝剂磁絮体形成的最佳参数及性能研究

本文系统研究了失盐及有机高分子絮凝剂与磁粉在高浊度原水中复合投加的絮凝效果和含磁絮体形成的最佳参数，并通过比较处理效果，出水沉降时间和含磁絮体的显微结构，验证了本磁絮凝方法处理高浊度原水效果更好，停留时间更短的预估，且絮体含磁易分离、为管式絮凝器采用磁絮凝和高梯度磁分离工艺提供了参数依据和高效絮凝分离一体化，管经的可行性证明。     

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。     

高浊度原水磁絮凝的分离实验

本文选择高浊度原水（浊工＝2000－2500，pH＝5－6）为对象在自制的磁分离装置上进行磁絮凝实验研究，结果表明原水经磁絮凝以后，其出水浊度均有不同程度的降低，原水流量、外加电流的不同能引起出水浊度较大的变化。     

鹊山水库突发低温高浊原水的处理工艺试验

通过中试试验,以PAM预沉+电絮凝反应/聚浮分离预处理作为UF膜前预处理,采用内压式UF膜应急处理突发低温、高浊度鹊山水库原水。试验结果表明,选用PAM预沉+电絮凝反应/聚浮分离作为UF膜前预处理可大幅度降低突发低温、高浊度原水的浊度、色度、COD_(Mn)和氨氮。UF膜运行过程中,跨膜压差、出水浊度的变化与UF膜前预处理后出水浊度波动幅度一致,但UF出水浊度、pH始终稳定。运行过程中,随着UF膜对进水的高浊度和大颗粒去除,与常规UF膜的COD_(Mn)去除率相比,该运行条件下的UF膜的COD_(Mn)去除率较高。随着运行时间的延长,UF膜跨膜压差增大,UF膜的COD_(Mn)去除率缓慢下降。运行过程中,UF的平均出水浊度、COD_(Mn)(以O_2计,mg/L)、pH和NH_3-N(以N计,mg/L)分别为0.20±0.07 NTU、1.98±0.20 mg/L、8.07±0.01和0.09±0.07 mg/L。结果显示,经由PAM预沉+电絮凝反应/聚浮分离预处理后的突发低温、高浊度鹊山水库原水可选用内压式UF膜应急处理,且COD_(Mn)去除率、出水浊度和pH稳定。     

双侧堰辐流式二沉池出水存在的问题及其机制分析

针对合肥市望塘污水处理厂辐流式二沉池集水渠附近有大量小絮凝体出现的情况,对集水渠附近的流速及沿池径方向SS指标进行了监测,分析了沉淀池的运行状况。结果表明,在辐流式二沉池的水面上,SS浓度最低的位置在距离池壁3.0～4.0 m之间;辐流式沉淀池进水流速较大,湍动能较大,不利于污泥沉降;沉淀池内存在明显的异重流,导致池壁处的上升流速较大,易将小絮凝体夹带至出水渠附近,导致出水效果不理想。     

PAM-絮体强化低浊细泥悬浮液絮凝试验研究

针对难沉降低浊细泥悬浮液,采用有机药剂PAM,以出水浊度和絮体平均沉降速度为评价指标,对投加PAM-絮体强化PAM处理低浊细泥悬浮液的絮凝效果进行了试验研究。对比了单独投加PAC和PAM的处理效果,同时还研究了絮凝剂用量、PAM-絮体投加量、水力条件、药剂投加顺序以及水样浊度等因素对处理效果的影响。研究结果表明:向悬浮液中投加一定数量、适当大小的PAM-絮体,不仅能充分发挥PAM絮凝沉降时间短的优势,同时可显著降低出水浊度,减少药剂用量,降低成本,具有强化絮凝的效果。     

混凝浑液面沉速与混凝剂投加量的关系研究

探讨了黄河高浊度水混凝沉淀浑液面沉速与自然沉速之间的相关性,经过对实验数据进行线性回归提出了混凝过程中浑液面沉速与自然沉速、含沙量、PAM投加量之间的经验公式。运用该经验公式得出的浑液面沉速计算值与实测相对误差在0.43%～12.27%之间。     

错流旋转填料床气相压降的研究

利用空气-水系统对错流旋转填料床的气相压降进行了实验研究。采用因次分析的方法推导出错流旋转填料床气相压降的无因次关联式。结果表明,错流旋转填料床欧拉准数在旋转填料床转速与气速之比(旋流比)小于30时,欧拉准数随旋流比的增大反而减小;当旋流比大于30时,欧拉准数随旋流比的增大而增大。旋流比小于30时欧拉准数与填料层轴向厚度的0.9次方成正比,旋流比大于30时欧拉准数与填料层轴向厚度的0.5次方成正比。湿床旋流比小于30时,欧拉准数随进液量的增大而上升;旋流比大于30时,欧拉准数随进液量的增大而下降。     

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。     

膜分离技术深度处理抗生素废水的研究

针对抗生素废水,采用双膜法进行处理,处理之后的出水达到回用水的目的。过程对进膜前絮凝沉降工艺、陶瓷膜超滤工艺以及反渗透出水进行了研究。结果表明,在加入350 mg/L PAFC絮凝后,采用恒流量陶瓷膜操作工艺,经过反渗透过滤,出水COD能降到50 mg/L以下,电导率降到50 uS/cm以下,浊度降到0.2 NTU以下。     

Interaction mechanism of flocculants with coal waste slurry

Coal tailings are the inevitable by-product of coal mining and preparation plants, and often are problematic in terms of dewatering and solid-liquid separation. The interaction of multi-component fine coal tailings with various coagulants and flocculants are important in dewatering processes. Tunçbilek coal preparation plant wastes are composed of 81% inorganic solids with negative surface charges dominating at all pHs. The highest settling rate and turbidity values without flocculant are obtained at natural pH of 8.3 due to the presence of inorganic ions in the suspension particularly Mg²⁺and Ca²⁺that act as natural coagulants. Additon of medium and low charge density anionic flocculants with high molecular weight at natural pH produced higher settling rates at lower dosages than nonionic and cationic flocculants. It shown that the charge density of anionic flocculants has a significant effect on both settling rate and supernatant turbidity, also the settling rate increases with increasing the degree of anionicity. Anionic flocculants having high molecular weight and high anione charge density produced flocs at sufficient size necessary for settling conditions, yet anionic flocculants having low charge density were more effective in the clarification of suspensions containing clay minerals of high stability. The multivalent ions act as a bridge between negatively charged coal, quartz and clay minerals with anionic groups (-CH₂-(CH-CO)-COO groups) of the polymer. Non-ionic flocculants required higher dosages than other flocculants to achieve equivalent settling rates; though excellent turbidity values were obtained in most common pH values. Cationic flocculants of higher charge densities (%70) achieved good settling rates and low supernatant turbidities (9.9 NTU) at natural pH for a dosage of 119.7 g/t-solids flocculant. An interaction mechanism of each polymer type with different components of the tailings is proposed.     

Comparative study of the effects of experimental variables on growth rates of aluminum and iron hydroxide flocs during coagulation and their structural characteristics

In this study, the dimensions of over six thousand flocs were analyzed to quantitatively and comparatively investigate the effects of several experimental variables on the growth rate of aluminum (Al) and ferric (Fe) hydroxide flocs. Results show that Fe hydroxide flocs have faster growth rate than Al hydroxide flocs; and the average size of the former is larger than that of the latter. Increasing the concentration of the bivalent sulfate ion (SO₄²⁻), initial turbidity, or slow mixing rate, was able to increase the growth rate of both kinds of flocs. On the other hand, steady floc sizes were found to decrease with the increase in SO₄²⁻ concentration, initial turbidity, or shear rate. Fe hydroxide flocs are more prone to be influenced by the changes in the variables than Al hydroxide flocs. While the steady floc sizes became smaller when initial turbidity or slow mixing speed increased, the roundness and smoothness of flocs were found to increase, indicating that higher initial turbidity or larger slow mixing rate produces flocs with more regular and round shape. Furthermore, at a fixed shear rate, Fe hydroxide flocs are stronger than Al hydroxide flocs. However, Fe hydroxide floc sizes are much easier to decrease with the increase in slow mixing intensity.     

The influence of inclined plates on expansion behaviour of solid suspensions in a liquid fluidised bed — A computational fluid dynamics study

A significant increase in the particle sedimentation rate can be achieved by introducing inclined plates into conventional fluidised beds. In turn, high suspension densities are possible at fluidisation velocities in excess of the particle terminal velocity. The installation of the inclined plates, however, alters the dynamic characteristics of the fluidised bed, in particular, impacting upon the expansion behaviour of the suspension. In the present work a Computational Fluid Dynamics (CFD) approach was employed to investigate the influence of inclined plates on the expansion behaviour of solids suspensions in liquid fluidised beds. The model is based on the solution of the Eulerian multiphase equations for up to two different particle sizes with a continuous phase of water. The momentum equations treat hindered settling behaviour via the inclusion of a volume fraction dependent drag law. The computational model was validated against our experimental data and compared with the predictions of a kinematic model developed in one of our earlier works. In general the predictions made by both the CFD and the kinematic models were found to be in good agreement with the experimental results.     

Modeling of low viscosity oil-water annular flow in horizontal and slightly inclined pipes: Experiments and CFD simulations

To characterize the effect of pipe inclination, low viscosity, flow rate and inlet water cut on annular flow pattern, a low viscosity oil-water two-phase annular flow in horizontal and slightly inclined (+1°, +3° and +5°) pipes with diameter of 20 mm has been experimentally investigated. A modified VOF model based on the CFD software package FLUENT was used to predict the in-situ oil fraction and pressure drop. The experimental data indicate that annular flow appears at a medium-high water cut. The slip ratio increases with flow rate increase but decreases with increasing water cut. The changes are more significant as the degree of inclination increases. Pressure drop is strongly dependent on flow rate, as it increases rapidly as inlet flow rate increase. Good agreement between the experimental data and calculated results of slip ratio and pressure drop was obtained.     

絮凝处理后固相浓度对悬浮液粘度的影响研究

经絮凝处理后的固液悬浮体系,其粘度与固相浓度的关系可由笔者提出的四次多项式描述。该多项式是对只适用于低浓度体系的爱因斯坦线性模型的扩展,新的模型可分别体现流体介质、单个颗粒、线状絮体、面状絮体及体状絮体对体系粘度的贡献。经实验验证,所提出的四次多项式模型可很好地拟合实验数据。在固相浓度较低的时候,絮凝剂用量的增加并不改变体系的流变特性,只在固相浓度达到一定阈值后,絮凝作用才开始明显体现。在絮凝作用达到最大之前,随絮凝剂用量的增加,体系中单个颗粒对悬浮液粘度的贡献逐渐减小,而线状、面状及体状絮体的影响逐渐增大。絮凝剂过量时,絮凝作用下降,体现在体系粘度的降低。     

聚二甲基二烯丙基氯化铵对聚合硫酸铁处理冬季长江水的助凝效果

采用聚二甲基二烯丙基氯化铵(PDM)与聚合硫酸铁(PFS)复合制得的稳定型复合混凝剂,用于冬季低温长江水强化混凝脱浊处理。通过混凝烧杯试验,考察了PDM对PFS在脱浊效果和沉淀性能上的改进程度。结果表明:对温度为5～7℃,浊度为45 NTU左右的冬季长江水,PDM助凝效果明显,同时PFS与PDM的复配比例越低,复合混凝剂混凝脱浊效果越好。复合混凝剂中PFS的用量比单独使用PFS时的少。复合混凝剂能增大絮团的沉淀速度,克服冬季低温条件下单独使用PFS时絮体轻而细小、沉淀慢、破碎现象严重的问题,从而使沉淀出水水质能够迅速稳定地达标,同时,还可明显改善PFS处理时出水带色、腐蚀设备等问题。     

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.     

机械搅拌澄清池对低温高稳定原水处理调试

分析低温高稳定性原水的特性以及斜管机械搅拌澄清池的运行参数,首先查明澄清池出水浊度不达标的原因,然后提出机械搅拌澄清池的调试方案。通过对投加混凝剂药量的调节,排泥周期和搅拌机转速的调节,使得澄清池出水浊度能够达标。     

Transport processes during electrowashing of filter cakes

Applications of electric fields during washing of filter cakes increases the removal rate of ions from the cake mother liquor, and under appropriate conditions the field also increases the wash flow rate by electroosmosis. Experimental data that show the key effects of the fields on the rates of ion mass transfer are presented: with the downstream electrode acting as a cathode, cation removal rates are increased whilst the removal rate of the anions is decreased. The concentration profile of the cations with washing time shows an increase in concentration to a value above that of the mother liquor, before it decreases due to displacement by the fresh wash liquor. A model is formulated that describes the advection, dispersion, ion migration and electroosmosis transport processes in the cake. Numerical solution of the model gives cation concentration profiles at the exit of the cake that are in qualitative agreement with the experimental observations. Experimentally measured wash liquor flow rates tend to be lower than what traditional colloid science principles predict by a factor of 5-10: reasons for this difference, supported by experimental work from other researchers, are discussed.