无机混凝剂的形态对混凝的影响

通过理论分析和实验，批出无机混凝剂在水中有着多种水解形态。在这些形态中，固态氢氧化物对混凝效果起着主要作用，混凝剂的投加方式也是一个重要因素。     

混凝法对白石水库处理效果分析与讨论

实验采用铝盐、铁盐混凝剂对白石水库水进行处理，最后得出最佳混凝剂使出水水质符合生活饮用水标准。另外，利用二次混凝技术对去除效果也进行了分析，并分析讨论了影响混凝的主要因素，为工程实际奠定了实验基础。     

强化混凝对水力条件的要求

混凝过程中混凝剂的水解结合效力和水力条件是决定混凝效果的两个关键因素，其中快速搅拌（扩散和混合）处于核心地位，然而关于强化混凝过程中水力条件影响的报道较少。对配水进行强化混凝条件的选择试验，考察了混凝剂种类和快速搅拌时间及强度等对强化混凝效果的影响。通过测定絮凝指数（FI）、沉后水浊度及DOC等发现：影响有机物去除效率的关键因素是混凝剂的扩散过程和快速混合碰撞过程；200～250r／min（G值为106～145s^-1）的快搅速度和60s左右的快速搅拌时间即可满足强化混凝的要求；絮体在过度搅拌强度下的破碎对有机物的去除率没有显著影响。     

聚硅酸金属盐混凝剂的混凝效果研究

采用一种新型的聚硅酸金属盐混凝剂进行低浊水净化试验.以低浊度的广东省开平市潭江水为原水,通过试验测定投加不同Al/Fe值的聚硅酸金属盐混凝剂(PAFS)后,混凝沉淀出水的余浊、色度、残余铝含量及总铁含量,比较其在混凝过程中所表现出的不同特点及在混凝效果上的差异.初步验证了这种混凝剂处理低浊水质的适应性及混凝特性.最后对混凝机理进行了理论上的初步探讨.     

印染废水混凝脱色处理的特点

选取有代表性的七种混凝剂,包括无机混凝剂和有机混凝剂,对六种不同类型的印染废水进行了混凝脱色处理的对比实验。讲座了各种印废水混凝脱色处理的特点。     

无机混凝剂的研究及发展趋势

无机混凝剂的研究及发展趋势王东升韦朝海（华南理工大学）１前言混凝剂是混凝技术应用中关键之所在，主要可分为无机与有机两大类，另外介于无机、有机之间的混合型、复合型也有着一定的尝试与发展。由于无机混凝剂具有无毒（或低毒）、价廉、原料易得等多方面的优点，在...     

磁混凝沉淀技术在城市污水处理中的应用

介绍了磁混凝沉淀技术的工艺流程及最佳工艺参数，如加料顺序、搅拌强度、混凝剂投加量等，并通过工程实例，展示了该项技术用于市政污水中的处理效果。磁混凝沉淀技术由于其高速沉淀的性能，使其与传统工艺相比，具有处理速度快、效率高、占地面积小、投资小等诸多优点，目前在国内外得到了越来越广泛地应用。     

无机高分子聚硅酸盐混凝剂的研究与应用

对无机高分子聚硅酸盐混凝剂的制备、应用和混凝性能研究现状以及有关其絮凝形态、混凝机理、结构与性能之间关系等研究的新进展进行了评述。指出今后的研究应在侧重聚硅酸盐结构表征的同时进一步研究其絮凝形态及混凝机理，提高混凝性能和稳定性。     

造纸废水的混凝试验研究

造纸废水中由于含有木质素及其衍生物具有较高的色度和COD,水处理中多采用铝盐混凝剂通过混凝沉淀加以净化。混凝反应包括混合和絮凝两个过程,影响这两方面的因素很多,包括混凝剂的种类、混合速度、水质特征等等[1]。其中混凝剂的投加量、pH值影响着混凝反应进程和结果,也决定工程应用的基建与运行费用。本文就pH值和混凝剂投加量对造纸废水混凝反应的影响进行研究,浅谈造纸废水混凝反应的机理。     

混凝沉淀工艺深度处理污水厂二级出水的混凝剂优化

通过烧杯试验，确定了采用混凝、沉淀工艺深度处理城市污水处理厂二级出水时，最佳的混凝剂组合及投量。结果表明，铝盐混凝剂与PAM组合使用时比铁盐混凝剂与PAM组合使用时的处理效果更好，当PAC＋PAM的组合投量为20mg／L＋5mg／L或30mg／L＋1mg／L、硫酸铝＋PAM的组合投量为30mg／L＋5mg／L时，混凝、沉淀出水浊度为2．5～3．5NTU，COD为25-40mg／L，TP为0．06-0．12mg／L。由于混凝后水中所形成的絮体较小，难于沉淀，因此混凝沉淀工艺对SS的去除效果较差，实际工程中可考虑增设过滤单元。     

Enhanced coagulation for high alkalinity and micro-polluted water: the third way through coagulant optimization

Conventional coagulation is not an effective treatment option to remove natural organic matter (NOM) in water with high alkalinity/pH. For this type of water, enhanced coagulation is currently proposed as one of the available treatment options and is implemented by acidifying the raw water and applying increased doses of hydrolyzing coagulants. Both of these methods have some disadvantages such as increasing the corrosive tendency of water and increasing cost of treatment. In this paper, an improved version of enhanced coagulation through coagulant optimization to treat this kind of water is demonstrated. A novel coagulant, a composite polyaluminum chloride (HPAC), was developed with both the advantages of polyaluminum chloride (PACl) and the additive coagulant aids: PACl contains significant amounts of highly charged and stable polynuclear aluminum hydrolysis products, which is less affected by the pH of the raw water than traditional coagulants (alum and ferric salts); the additives can enhance both the charge neutralization and bridging abilities of PACl. HPAC exhibited 30% more efficiency than alum and ferric salts in dissolved organic carbon (DOC) removal and was very effective in turbidity removal. This result was confirmed by pilot-scale testing, where particles and organic matter were removed synergistically with HPAC as coagulant by sequential water treatment steps including pre-ozonation, coagulation, flotation and sand filtration.     

混凝剂中的铝形态对藻类混凝过程的影响

为了考察混凝剂中的铝形态对藻类混凝过程的影响,使用3种具有不同铝形态分布的混凝剂对含藻水进行了混凝试验。结果表明,硫酸铝由于具有较低含量的Alb,电中和能力较差,故需要较大的投量才能去除藻类,形成絮体;含藻水体系中的有机物主要是腐殖酸及富里酸类物质,微生物代谢产物(SMP)在硫酸铝作混凝剂时得到较好的去除,而腐殖酸及富里酸的去除率较低可能是造成硫酸铝混凝效果较差的原因;Alc(Al(30))在混凝中的作用机理主要是吸附架桥作用,可有效去除水体中的有机物,Al₁₃的主要作用机理是电中和作用,可以有效去除水体中的颗粒物;Al₁₃与Al₃₀由于具有形态的稳定性,其混凝过程受pH值的影响较小。絮体强度因子随着pH值的升高先增大后减小,Al₁₃作混凝剂时絮体恢复因子随pH值的升高先增大后减小,而其他两种混凝剂所形成絮体的恢复因子随pH值的升高而增大。     

Chemical coagulation of combined sewer overflow: heavy metal removal and treatment optimization

The coagulation of combined sewer overflow (CSO) was investigated by jar-testing with two commercial coagulants, a ferric chloride solution (CLARFER) and a polyaluminium chloride (WAC HB). CSO samples were collected as a function of time during various wet-weather events from the inlet of Boudonville retention basin, Nancy, France. Jar-tests showed that an efficient turbidity removal can be achieved with both coagulants, though lower optimum dosages and higher re-stabilization concentrations were obtained with the aluminum-based coagulant. Optimum turbidity removal also yielded effective heavy metal elimination. However, the evolution with coagulant dosage of Cu, Zn, Pb, Cr, soluble and suspended solids contents followed various patterns. The removal behaviors can be explained by a selective aggregation of heavy metal carriers present in CSO and a specific interaction between hydrolyzed coagulant species and soluble metals. Stoichiometric relationships were established between optimal coagulant concentration, range of optimal dosing, and CSO conductivity, thus providing useful guidelines to adjust the coagulant demand during the course of CSO events.     

A new inorganic-organic composite coagulant, consisting of Polyferric Sulphate (PFS) and Polyacrylamide (PAA)

Currently, research is focused on the synthesis of new composite coagulants, which are constituted of both inorganic and organic materials. In this paper, the development of relevant reagents was investigated, by combining the inorganic pre-polymerised iron-based coagulant Polyferric Sulphate (PFS) with an organic, non-ionic polymer (Polyacrylamide, PAA) under different PAA/Fe (mg/l) and OH/Fe molar ratios. Moreover, the new reagents were characterised in terms of typical properties, stability and morphological analysis (XRD, FTIR, SEM). Their coagulation performance, when treating low or high turbid kaolin-humic acid suspensions, was also investigated, whereas the applied coagulation mechanisms were discussed by using the Photometric Dispersion Analysis (PDA) analysis. The results show that the new coagulation reagents present improved properties, including increased effective polymer species concentration, and they exhibit very good stability. The respective tests using PDA confirmed that the predominant coagulation mechanism of PFS-PAA is the bridge formation mechanism. Coagulation experiments in low or high turbid kaolin-humic acid suspensions reveal that the novel composite reagent PFS-PAA exhibits better coagulation performance, when compared with simple PFS, in terms of zeta-potential reduction, turbidity and organic matter removal and residual iron concentration.     

Return sludge employed in enhancement of color removal in the integrally industrial wastewater treatment plant

In this study, the recirculation of chemical sludge and integrated sludge were employed for enhancement of color removal in an integrally industrial wastewater treatment plant. The jar test was conducted for simulating chemical coagulation process with different coagulants, aluminum sulfate and polyaluminum chloride (PACl), after different activated sludge systems (with air or high-purity oxygen). The results showed that with sludge recirculation the process of coagulation for the color removal has up to 35% enhancement in comparison with no sludge recirculation. Meanwhile, the color removal enhancement of coagulant aluminum sulfate was approximately 2 to 3-times the color removal enhancement of coagulant PACl at the optimum ratio of return sludge. In coagulation process with influent color of 1220 true color unit (TCU), the optimum dosage of return sludge was 3010mg/L, when coagulant PACl or aluminum sulfate was employed. In coagulation process with influent color of 536 TCU, the optimum dosages of return sludge were 2340 and 4680mg/L using PACl and aluminum sulfate, respectively.     

Chemical aspects of coagulation using aluminum salts—II. coagulation of fulvic acid using alum and polyaluminum chloride

This is the second of a two-part series investigating chemical aspects of coagulation using AI salts. Part I of the series examined the hydrolytic reactions of AI. In this paper, the coagulation of fulvic acid (FA) by alum and polyaluminum chloride (PACI) is examined. An Al speciation methodology was used to examine complexation reactions between Al and FA for water treatment conditions. From pH 5 to 7 and at typical coagulant doses, hydrolysis and complexation of Al is described by a simple model based on the reaction stoichiometry between AI, FA and OH⁻. Model results show that when alum is used as a coagulant, Al complexed with FA is hydrolyzed to a ligand number, This is similar to the ligand number for the prehydrolyzed PACI and explains similarities in dose requirements for these coagulants. Effects of temperature on coagulation performance are shown to be largely chemical in nature. Chemical aspects of coagulation are discussed and the importance of complex formation in coagulation is examined.     

Premembrane treatment of drainage waters from dumps of solid domestic wastes

We examined the efficiency of pretreatment, prior to membrane purification, of drainage waters from domestic refuse dumps using oxidants, adsorbents, coagulants, and flocculants. We determined the optimum pH values for coagulatory processes and the optimum coagulant concentrations, and found that the most effective coagulant for these drainage waters was basic aluminum sulfate. Results of our experiments on a pilot facility incorporating units for coagulation and the reverse-osmosis desalting of the refuse dump drainage waters demonstrated the possibility of obtaining a permeate that met the requirements prescribed for discharge into the sewerage system.     

Effects of raw water conditions on solution-state aluminum speciation during coagulant dilution

The speciation of aluminum in solutions of alum and various prehydrolyzed, aluminum-based water treatment coagulants was investigated by 27Al NMR at 5 degrees C and 25 degrees C. Alum solutions were seen to contain only mononuclear species including an AlSO4(+) complex, while the prehydrolyzed coagulant solutions contained polynuclear aluminum species, as well. The relative proportions of both polynuclear species and AlSO4(+) complex decreased in cold water. The presence of organic matter had little effect on the speciation of aluminum in diluted alum, but markedly reduced the relative proportion of the tridecamer species in the prehydrolyzed coagulant solutions. The relationship between Al speciation in the coagulants and organic matter removal during jar tests was considered, and the possible role of sulfate in both the formation of the tridecamer species and the effect of organic matter on coagulation efficiency was discussed.