混凝土拌合站污水快速处理技术研究

隧道拌合站沉淀池无法有效沉淀污水中细小固体颗粒,属于富含钙离子的强碱性污水。实验采用细粒高岭土模拟污水,选用阴离子型聚丙烯酰胺对污水进行絮凝处理。利用水中钙离子作为反离子降低固体颗粒ζ电位,从而降低颗粒间静电斥力使得聚丙烯酰胺架桥吸附作用效果提升。实验研究了聚丙烯酰胺分子量、投药量、搅拌速度、搅拌时间和pH对絮凝效果的影响。还根据实验所得最佳絮凝参数对现场污水进行实验,絮凝处理效果理想。     

稠油污水絮凝除硅处理方法——屈撑囤,王新强,宋绍富,等.CN101781037A

一种稠油污水絮凝除硅处理方法,由调pH及除硅、絮凝除油步骤组成。本发明的稠油污水絮凝除硅处理方法,采用季铵碱与无机碱的复合物调整污水pH,在CaCl2与MgCl2复合除硅剂和阳离子有机聚合物的强化作用下,达到稠油污水     

塔河油田含稠油降粘剂污水絮凝处理研究

对塔河油田应用和未应用降粘剂开采的典型稠油单井及二、三号联合站混合水进行取样分析,开展了絮凝剂筛选和评价,筛选出的絮凝剂DL-1与聚丙烯酰胺复合使用,可以满足生产需要,并确定了最优使用浓度;研究了化学降粘剂对污水絮凝沉降处理的影响,证明目前所用剂量的降粘剂对污水絮凝沉降没有显著负面影响,但会导致来水含油量上升,增加污水处理系统负荷;研究了降粘剂含量及污水pH值对絮凝沉降剂效果的影响,明确了絮凝剂的使用条件。     

制浆造纸工业的污水污泥处理研究

论述了对制浆造纸工业的污水经化学絮凝法分离出污泥，并对污泥进行消化处理。     

制浆造纸工业的污水污泥处理研究

论述了对制浆造纸工业的污水经化学絮凝法分离污泥，并对污泥进行了化处理。     

含血污水的变性及絮凝处理研究

针对屠宰过程中的含血污水难以絮凝处理的问题，首先对其进行了适当的变性处理，然后将各段废水集中进行了絮凝处理研究，考察了多种絮凝剂的处理效果。结果表明，含血污水经过变性预处理后采用硫酸亚铁和氧化钙复合絮凝剂处理后，可得出理想的处理结果，出水COD可达187．4mg/L，色度值为75度。此方法简便、高效、有很好的环境和经济效益。     

抛光砖生产企业污水的絮凝沉降净化处理

介绍了抛光砖生产企业污水的构成及污水絮凝沉降净化处理系统的工艺流程、工作原理等。它具有结构紧凑、占地面积小、管理费用低、污水处理能力大、固体悬浮物沉降速度快、污水净化处理后固体悬浮物含量低（通常小于10ppm）、能循环使用、节约用水及保护了人类赖以生存的日益贫乏的水资源等优点，是抛光砖生产企业污水净化处理的最佳选择。     

新型复合絮凝剂在城市污水处理中的应用研究

为了提高城市污水的絮凝处理效率，以磁性纳米Fe₃O₄粒子、Na₂Si O₃、Al₂(SO₄)₃·18H₂O和羧甲基淀粉钠为原料，制备了一种适合城市污水絮凝处理的新型复合絮凝剂FAS-1，并对其综合性能进行了评价。实验结果表明，絮凝剂FAS-1的加量越大、沉降时间越长，污水中COD和浊度的去除率就越高；而随着污水pH值的逐渐升高，COD去除率和浊度去除率均呈现出先增大后减小的趋势；实验温度对絮凝处理效果的影响相对较小；当絮凝剂FAS-1的加量为20mg·L^-1、污水pH值为8、实验温度为30℃、沉降时间为40min时，污水的COD去除率和浊度去除率分别可以达到98.7%和96.8%，达到了良好的絮凝处理效果。研究结果认为，新型复合絮凝剂FAS-1能够满足目标城市污水絮凝处理的需求，具有良好的推广应用前景。     

抛光砖生产企业污水的絮凝沉降净化处理

介绍了抛光砖生产企业污水的构成及污水絮凝沉降净化处理系统的工艺流程、工作原理等。它具有结构紧凑、占地面积小、管理费用低、污水处理能力大、固体悬浮物沉降速度快、污水净化处理后固体悬浮物含量低(通常小于10ppm)、能循环使用、节约用水及保护了人类赖以生存的日益贫乏的水资源等优点,是抛光砖生产企业污水净化处理的最佳选择。     

吸附型生物絮凝剂ZL5-2的制备及在水处理上的应用

研究了吸附型生物絮凝剂ZL5-2对印染污水、炼油污水、生物工程发酵液的絮凝作用．并同聚合铝絮凝剂对污水和发酵液的絮凝作用进行了比较。经ZL5-2絮凝作用。炼油污水絮凝率为74．7％,COD去除率为32．4％,BOD去除率为55．4％;印染污水絮凝率为65．8％,COD去除率为49．5％,BOD去除率为62．3％;青霉发酵液和灰色链霉菌发酵液絮凝率最高可分别达到68．4％和69．0％。     

Design and function of novel superplasticizers for more durable high performance concrete (superplast project)

In this article we shall describe our quest and ultimate success in furthering our understanding of the action of superplasticizers on the rheology of cement and concrete. By specifically producing superplasticizers with varied architectures, we have been able to show the important structural features of the macromolecules that lead to a successful superplasticizer or water reducing agent. Both polycarboxylate and lignosulfonate polymers have been investigated. Using both non-reactive model MgO powders, three different types of cement blends, the adsorption behaviour and the effect on the rheological properties of these two important superplasticizer families have been used to further develop a conceptual model for superplasticizer — cement behaviour. This paper will deal mainly with the conceptual model, the materials and methods used to asses the polymer adsorption behaviour and rheological properties of the systems studied. We shall briefly describe the adsorption of the polymers onto the different surfaces and their influence on surface charge and rheology and the influence of the various ionic species found in cement pore solutions that may influence polymer-cement affinity. The key factors are shown to be the effective adsorbed polymer thickness and the induced surface charge which can be influenced by the polymer architecture, the pore solution composition and the initial particle surface charge.     

Effect of plasma treatment of polymeric tape carriers on wetting behaviour of aqueous ceramic tape casting slurry

Due to environmental and health aspects, aqueous ceramic slurries are preferred to traditional organic solvent systems in tape casting. An important obstacle associated with the high surface energy of water is poor wetting of aqueous ceramic slurries on polymeric tape carriers. Therefore, we measured the contact angles of an aqueous epoxy-based ceramic slurry on polyethylene terephtalate (PET), polypropylene (PP), polymethyl methacrylate (PMMA), and aluminium-coated polyethylene terephtalate (PET-Al) films and investigated approaches to improving their wetting. We evaluated the effect of plasma treatment of the tape carrier surface on the wetting behaviour and compared it with the effect of adding non-ionic amphiphilic surfactants to the ceramic slurry. The treatment of the tape carrier surface by low-temperature plasma substantially improved the wetting behaviour of aqueous ceramic slurry. The lowest contact angle of 31° was obtained on the PET film. Although the addition of non-ionic surfactants improved both the wetting behaviour of the slurry and the detachment of the polymeric carrier from the ceramic tape even better than the plasma treatment of the carrier surface did, the plasma-treated carriers still present a useful alternative to the surfactants. In the case of the plasma-treated PET carrier the surfactants could be fully eliminated and potential drawbacks related to the use of surfactants could be prevented.     

Influence of bleed water reabsorption on cement paste autogenous deformation

The effects of bleed water reabsorption and subsequent early age expansion on observed autogenous deformation are investigated in this research. Bleeding was induced by varying superplasticizer and shrinkage-reducing admixture dosages and by increasing the water-to-cement ratio. This research revealed that significant early age expansion occurs with increasing chemical admixture dosages and higher water-to-cement ratios, as expected, due to increasing bleeding of those samples. When samples were rotated, negligible early age expansion was observed. Thus, bleed water reabsorption is shown to be the primary mechanism causing initial expansion in sealed autogenous deformation samples. Thermal dilation and ettringite growth appear to have a minimal influence on the observed expansion. Rotating the samples during setting eliminates the potential for bleed water reabsorption and is recommended for all autogenous deformation testing.     

Modelling of ageing effects on crack-bridging behaviour of AR-glass multifilament yarns embedded in cement-based matrix

This article focus on modelling of ageing effects on crack-bridging behaviour of AR-glass multifilament yarns embedded in cement-based matrix. In the first step, age-dependent changes in the crack-bridging behaviour of AR-glass multifilament yarns were investigated at the meso and micro levels. Two cementitious matrices were considered where the binder contained Portland cement clinker and ground granulated blast furnace slag cement, respectively. Mechanical characteristics of the bond between matrix and multifilament yarns after accelerated ageing were measured by means of double-sided yarn pullout tests. In these tests the multifilament yarns bridged a single crack in the matrix arising in a notched area of the specimen. Losses in performance with increasing age differed widely depending on matrix material composition. The essential cause of such losses was discovered to be the microscopic densification of the fibre-to-matrix interface. This led to increased bond intensity and restricted slip-ability of the filaments. Subsequently, these micro-structural phenomena were related to the mesoscopic material behaviour by means of a phenomenological bond model. This cross-linkage model describes the crack-bridging effect of the entire multifilament yarn at the single filament level. According to the model, each filament possesses a specific deformation length depending on its position in the cross-section of the yarn. This deformation length depends on bond characteristics between single filament and cementitious matrix, which vary with age. Characteristic values of the model were computed from load-crack width curves obtained from the yarn pullout tests. The changes in the microstructure were represented by the characteristic values of the model.     

Effect of TEA on fly ash solubility and early age strength of mortar

The investigations focused on the dissolution behaviour of fly ash in alkaline solution and the effect of triethanolamine (TEA) addition. TEA is known as a grinding aid in cement production and is an Al and Fe chelating agent. To determine the effect of TEA on the dissolution behaviour of fly ash constituents, fly ash was mixed with a KOH solution at pH 13 and different dosages of TEA. Samples were taken after different times and analysed by ICP-OES. The effect of TEA on the heat evolution rates of fly ash cement pastes was investigated using isothermal calorimetry. Strength tests were also conducted to investigate the effect of TEA on plain Portland cement and fly ash/cement mortars. TEA was found to increase the dissolution rate of Al, Ca and Fe from fly ash. A slight, but reproducible, effect on heat evolution rates and an increase in early age strength was observed for fly ash cements.     

Green preparation of in situ Cr3C2 nano-coatings on graphite surface and their water-wettability and rheological properties

Cr₃C₂ coatings were successfully prepared on the surface of graphite flakes via a molten salt route by mixing Cr powders with natural graphite flakes in a binary LiCl-KCl salt at 450–950?°C for 4–12?h. The phases and microstructures of the coatings were verified by its XRD/XPS spectra and SEM/AFM observations, respectively. Together with the dissolution/dispersion evidence of chromium powders after interaction with the salt, and the slightly increased particle sizes due to the formation of Cr₃C₂ coatings on graphite flakes, a ‘template-growth’ kinetic process was therefore proposed on the formation of such coatings in the molten salt. The resultant coatings decreased the contact angle between water and graphite from 101° to ~ 75° and lowered the apparent viscosities of graphite water slurry by two orders of magnitude accordingly, suggesting that the coatings will afford graphite with good processing abilities for carbon-water based materials.     

Influence of the nature of aggregates on the behaviour of concrete subjected to elevated temperature

An experimental study is carried out on concretes composed of three different types of aggregates: semi crushed silico-calcareous, crushed calcareous and rolled siliceous. For each aggregate type, two water/cement ratios (W/C), 0.6 and 0.3 are studied. Aggregates and concrete specimens were subjected to 300, 600 and 750 °C heating–cooling cycles. We analyse the evolution of thermal, physical and mechanical properties of concrete in terms of behaviour and physical characteristic evolutions of aggregates with temperature. The study of thermal behaviour of aggregates showed the importance of initial moisture state for the flints. The crystallisation and microstructure of quartz play an important role in the thermal stability of siliceous aggregates. The residual mechanical behaviour of concrete varies depending on the aggregate and the influence of aggregates is also dependent on paste composition. This study allowed to better understand the influence of chemical and mineralogical characteristics of aggregates on the thermomechanical behaviour of concrete.     

Nonlinear ultrasonic evaluation of load effects on discontinuities in concrete

The presence of discontinuity surfaces in concrete structures, i.e. two or more layers in contact, may be an existing situation with evident relapses on damage formation and progression. Differences occur depending on the type of discontinuity, which could be a thin weaker layer or a pre-existing crack. The behavior of pre-existing interfaces is here studied by means of the Scaling Subtraction Method, a Nonlinear Ultrasonic Non-Destructive Technique, that revealed to be effective in describing the mechanical evolution of concrete samples with discontinuity surfaces under the effects of compressive loads.     

Experimental determination of the effective anionic charge density of polycarboxylate superplasticizers in cement pore solution

The specific anionic charge density of polycarboxylate superplasticizers can be determined experimentally by titration with a cationic polyelectrolyte. In this study, the anionic charge densities of several polycarboxylates based on methacrylate ester chemistry were measured in aqueous solution at pH 7 and 12.6, resp., and in cement pore solution. The anionic charge of the polycarboxylates increases with increasing pH value as a result of deprotonation of the carboxylate groups in the polymer backbone. Addition of Ca²⁺ ions generally causes a decrease of the anionic charge density. The reduction in anionic charge varies and depends on the architecture of the polycarboxylate. The effect results from the binding of calcium ions by the carboxylate groups, both through complexation and counter-ion condensation. Consequently, the effective anionic charge density of polycarboxylates in cement pore solution can differ significantly from the charge density which is calculated based on the chemical composition. Generally the -COO⁻ functionality may coordinate Ca²⁺ as a monodentate or bidentate ligand. The type of coordination depends on the steric accessibility of the carboxyl group. In PC molecules possessing high side chain density, the -COO⁻ group is shielded by the side chains and coordinates as bidentate ligand, producing a neutral Ca²⁺-PC complex. Accordingly, this type of PC shows almost no anionic charge anymore in cement pore solution. In PCs possessing high amount of -COO⁻, Ca²⁺ is coordinated monodentate, resulting in an anionic complex. Consequently, this type of PC shows significant anionic character in pore solution. Its adsorption behaviour is determined by a gain in enthalpy which derives from the electrostatic attraction between the PC and the surface of cement. This way, by utilizing the relatively simple method of charge titration, it is possible to assess the electrostatic attraction which, besides entropy gains, is the driving force behind the adsorption of polycarboxylates on the cement surface and thus determines their effectiveness as dispersing agent. The findings are generally applicable to other anionic admixtures used in cement.     

Influence of chemical degradation on mechanical behavior of a petroleum cement paste

Cement paste used in the Oil Industry is generally subjected to chemical degradation due to flow of acid fluids in various situations. The present study focuses on the evolution of thermo-hydro-mechanical (THM) behavior with chemical degradation of petroleum cement paste. Triaxial compression tests with different confining pressures (0, 3, 10 and 20 MPa) are carried out on a standard oil cement paste in sound state and completely degraded state by ammonium nitrate solution under a temperature of 90 °C. The results obtained show that the material in its initial state exhibits a small elastic phase and a strong capacity of compaction. The mechanical behavior depends on the load induced pore water pressure. Because of the increase in porosity caused by chemical degradation, the mechanical strength (cohesion and friction angle) and Young's modulus decrease. The dependence of mechanical strength and Young's modulus on confining pressure is smaller in the chemically degraded cement paste than in the sound one. In fine, the mechanical behavior of the whole material becomes more ductile. As a result, such effects of chemical degradation should be taken into account when modeling such cement paste materials exposed to such chemical degradations.