PAC投加对絮体破碎后再絮凝特性和颗粒去除的影响

为改善絮体破碎后的再絮凝能力,提高颗粒的去除效率,以西宁地区低温低浊水为研究对象,通过光学检测仪器及数学拟合方式,分析补投聚合氯化铝(PAC)对破碎后絮体粒径与分布、生长速率变化的影响,描述颗粒及浊度的去除效果.结果表明:随PAC补投量的升高,絮体粒径和生长速率均先增大后减小,各自达到峰值所需补投药量分别为4和6 mg/L;剩余浊度和颗粒数先降低后升高,最低时可分别降至0.79 NTU、90个·m L-1.补投2 mg/L药剂后,280~630μm絮体颗粒体积分数由22.85%增大到46.36%,4~35μm絮体颗粒体积分数由1.21%减小至0.19%,再絮凝后絮体平均粒径为400μm,大于未破碎前的370μm,粒径增长率为8.11%,絮体生长速率为77.26μm/min.补投PAC可促进絮体破碎后的再絮凝,提高浊度及颗粒数的去除效果,可有效改善实际工程絮凝工艺效果.     

絮凝过程絮体粒度分布特征及流场仿真

絮凝主要用以改变水中悬浮颗粒的粒度分布.絮凝反应设备创造的水力条件直接影响其内部三维流场的分布,进而对絮体成长及粒度分布起决定性作用.以聚合氯化铝(PAC)为絮凝剂、水中高岭土悬浮颗粒为去除对象,采用浊度仪、颗粒计数仪等在线仪器对絮凝过程进行实时监测和数据记录,研究改变反应条件对动态絮凝过程絮体粒度分布及絮凝效果的影响,并对絮凝反应器内三维流场进行了仿真计算,有助于改善反应设备水流状态和强化絮凝效果.     

高分子絮凝剂质量浓度对泥沙絮体分形结构的影响

在黄河泥沙高质量浓度悬浊液中投加阳离子高分子聚合物,采用沉降技术与图像分析技术,探讨了聚合物的架桥絮凝机理以及不同质量浓度聚合物下架桥絮体粒径发展变化趋势,利用分形特性表征参数“分维”定量分析了不同质量浓度对絮体分形结构的影响,得出:①阳离子聚合物对泥沙颗粒的絮凝作用以架桥絮凝机理为主,电性中和机理为辅;②不同高分子质量浓度下泥沙架桥絮体粒径分布均呈广义的正态分布,不同絮凝阶段絮体存在3个粒径分布区域;③高分子质量浓度存在一个最佳值.合适浓度下的高分子架桥絮体结构密实、沉速快,静沉实验中上清液余浊低,分维值高,絮凝效果好.     

给水絮凝处理中壳聚糖的助凝作用和机理

为能高效除浊,又能去除水中有机污染物,将无机絮凝剂聚合氯化铝与天然高分子絮凝剂壳聚糖协同使用,用于自来水厂的给水絮凝处理.考察助凝剂壳聚糖投加量、pH、壳聚糖相对分子质量等因素对浑浊度和有机物去除效果的影响,采用微电泳仪测定了絮凝过程中溶液Zeta电位的变化,通过电子显微镜和im-ageJ图像处理软件,对絮体形态进行分析.结果表明,在以黄河水为水源的自来水厂的给水絮凝处理中,以壳聚糖(CTS)作为聚合氯化铝(PAC)的助凝剂,pH为7.5时,PAC投加35mg/L,CTS投加0.15mg/L时,壳聚糖的助凝效果显著.壳聚糖的絮凝以吸附架桥为主,电性中和为次.显微摄像系统絮体的形态分析表明,单加PAC、PAC/CTS协同絮凝处理水样后絮体的分形维数分别为1.294和1.385.     

粘性泥沙动水絮凝沉降数值模拟及影响因素

基于扩散受限絮团聚集模型(DLCA模型),将絮凝沉降模型和水动力学结合,从三维的角度对动水中粘性细颗粒的絮凝沉降过程进行了计算机模拟.在此基础上,分析了有效碰撞系数、泥沙初始浓度和粒径对均匀沙和非均匀沙的落淤距离与分布的影响,初步研究了粘性细颗粒泥沙的絮凝沉降分形生长过程,并对絮凝体进行了图像处理.研究成果对黄河等高浊度细颗粒含沙水流的治理与处理有一定的理论和实际应用价值.     

微细粒钛铁矿和钛辉石的剪切絮凝浮选行为

通过矿物可浮性试验、粒径测试、光学显微镜测试、浊度沉降法和颗粒间相互作用的计算,对微细粒钛铁矿和钛辉石的剪切絮凝浮选行为进行分析.结果表明,适宜的搅拌强度和搅拌时间可提高微细粒钛铁矿和钛辉石的可浮性,搅拌强度对剪切絮凝的影响随颗粒疏水性的增强而变小,絮体粒径随搅拌强度的增加而明显增大.钛辉石形成的絮体主要为开放型的枝链状结构,而钛铁矿絮体枝链闭合,较为密实;矿物的剪切絮凝行为与矿物可浮性的变化是一致的,这两种矿物颗粒在捕收剂溶液中均能发生絮凝行为.     

颗粒活性污泥法处理COD和浊度效果的研究

以模拟废水为处理对象,考查了活性污泥在稳定期、污泥颗粒期、曝气改善期三种状态下对CODcr和浊度的去除效果.实验结果表明：稳定期的CODcr去除效果最好,说明絮体污泥比颗粒污泥更有利于污染物的去除.曝气改善期浊度去除率最好,说明污泥颗粒化有利于提高污泥的沉降性能并降低出水浊度;同时,污泥颗粒化后需要提供合适的曝气强度使颗粒污泥保持合适的粒径,以稳定系统的出水水质.     

微絮凝-超滤联用工艺处理低温水膜污染的机理

通过微絮凝-超滤联用工艺处理不同温度水样,研究了微絮凝过程中有机物的去除效果、形成絮体特性的差异以及温度的不同所造成超滤膜污染的主要机理。结果表明:微絮凝过程对低温水样的有机物去除率优于常温水样;尽管不同温度水样微絮凝过程中形成絮体的大小差异不大,但低温水样形成絮体的分型维数要明显小于常温水样,这说明低温水样形成的絮体结构更加疏松;不论是低温水样还是常温水样,滤饼层阻力都在造成膜污染的膜阻力因素中占主导地位,与常温水样相比,低温水样有较高的相对膜通量,说明低温水样形成的絮体造成的膜污染程度要比常温水样轻,这与低温条件下所形成絮体的特性密切相关。     

用颗粒计数和浊度联合评价颗粒物去除作用

采用浊度检测和颗粒计数技术评价了高锰酸盐复合剂预氧化工艺对滤后水中颗粒物的去除效果。结果表明,PPC预氧化能有效地强化滤后水中颗粒物去除效果,使颗粒总数降低幅度达65.0%,采用浊度指标不能有效地反映滤后水质的变化,将浊度检测与颗粒计数技术相结合,能更有效地反映滤池对颗粒物质的去除效果。     

混凝-超滤系统中混凝剂对絮体特性及膜污染的影响

采用腐殖酸(HA)配水考察混凝剂类型和投加量对水中有机污染物去除效果、膜污染构成及发展规律的影响,并探讨絮体粒径、密实度等形态特征与絮体滤饼层阻力间的内在联系.结果表明:PAC和Fe Cl3作为混凝剂均能有效地去除水中的HA,但以Fe Cl3作为混凝剂时膜污染更加严重.在较低混凝剂投加量下,PAC和Fe Cl3产生的絮体细小,容易形成致密滤饼层,导致过滤阻力增大;随着混凝剂投加量的增加,絮体更容易碰撞成长,粒径增大,形成结构疏松的滤饼层,减小过滤阻力;与PAC相比,Fe Cl3絮体结构更加密实,因此滤饼层导致的膜污染更加严重.     

Effects of symmetrically alternative rotating flow on flocculation

1　INTRODUCTIONTheflocculationisusuallydefinedasaprocessinwhichthedestabilizedsolidparticlesareaggregatedbythebridgingofpolymericflocculants .Theformationofflocsisdeterminedbytwosteps.Oneistheap proachingandcollision ,theotheristheflocgrowing .Thecollisionisachievedbythreemechanismsinclud ingtheBrownianmotionof particles ,namedasperikineticflocculation ;thedifferencesinsettlingve locityofparticleswithvarioussizes ,socalleddiffer entialsettlingandtheimposedfluidvelocitygradientsfrommixing …     

微气泡曝气中活性污泥混合液性质变化

采用SPG膜微气泡发生系统,考察微气泡曝气过程中,污泥混合液性质的变化及相关关系,包括污泥粒径、污泥EPS质量浓度、上清液浊度和有机碳质量浓度、混合液黏度和表面张力等.结果表明,在微气泡发生系统中液体循环泵的水力剪切作用造成污泥絮体破碎及污泥粒径减小.在该过程中,污泥EPS释放,上清液浊度和有机碳（特别是胶体有机碳）质量浓度升高,同时污泥絮体的再絮凝能力严重丧失.污泥EPS物质的释放导致混合液黏度增加,但混合液表面张力保持不变.相关性分析表明,污泥粒径减小及污泥EPS释放是造成混合液其他性质变化的主要原因.与离心型循环泵相比,蠕动泵水力剪切作用较弱,对混合液性质的影响较小.微气泡曝气中污泥混合液性质的变化会加速膜过滤过程的膜污染.     

Correlating common breakage modes with impact breakage and ball milling of cement clinker and chromite

Understanding the mechanisms of the breakage of ore particles is important to predict the particle size distribution in size reduction operations. This paper aims to show the presence of common breakage modes in impact breakage and ball milling of the cement clinker and chromite samples. For that purpose, narrow size fractions of the two samples were broken in a drop-weight tester or ball mill by changing the degree of applied energy. Then the resultant size distributions were evaluated to seek evidence for the common breakage modes. The results showed that increasing the breakage energy will produce a systematic change in the shapes of the size distributions, suggesting a sequential set of breakage modes. The breakage is initially due to tensile stresses at low breakage energies and compressive stresses at high breakage energies. Further studies should be done to assess if these breakage modes occur at size-reduction of different ores.     

Enhanced treatment of water with low turbidity：Combined effects of permanganate, PAM and recycled sludge

The effectiveness of enhancing treatment of water with low turbidity through combined effects of permanganate oxidation, PAM aiding coagulation and sludge recycling was investigated through continuous bench scale studies. In comparing with ferric chloride coagulation, only recycling sedimentation sludge was ineffective in enhancing treatment of water with low turbidity. PAM with recycled sludge showed positive effects, and the additional permanganate dosing exhibited the best potential of favoring coagulation, which leaded to much lower effluent turbidity and CODMn. Additionally, it was observed that the optimal permanganate dosage was 0.4 mg/L and the higher permanganate dosage exhibited inhibiting effects for pollutants removal. SEM analysis indicated that the flocs were loosely formed and the particle diameter was critically low for ferric chloride coagulation process. Comparatively, the addition of PAM and permanganate with recycled sludge facilitated the aggregation of tinny particles onto compact PAM polymer chains, therefore contributing to the formation of compact flocs with high particle diameter. The combined employment of recycled sludge, PAM and permanganate showed the best potential of favoring coagulation, mainly through synergistic effects between seeding, polymer bridging and increasing effective collision in mechanism. Additionally, the variation of Fe and Mn concentration after recycling and sedimentating units was studied for the processes, and the main species was also investigated for elements Fe and Mn. Sludge recycling and permanganate addition did not increase Fe and Mn concentration in the sedimented water.     

Breaking and Characteristics of Ganoderma Lueidum Spores by High Speed Entrifugal Shearing Pulverizer

The spores of Ganoderma lucidum were ground and broken to ultrafine particles by high speed centrifugal shearing（HSCS） pulverizer. The characteristics of Ganoderma lucidum spores were analyzed by scanning electron microscope （SEM）, Fourier transform infrared spectrophotometry （FTIR）. Ultraviolet-visible pectrophotometer was used to determine the extraction ratio of aqueous solubility polysaccharide between the raw and broken spores. The immunological function on the mice before and after the breaking of spores wan investigated. The experimental results show that after being ground, the sporoderm-broken ratio reachs 100%, the original active ingredients of ganoderma lucidum spores do not change, and the extraction ratio of aqueous solubility polysaccharide is greatly increased by 40.08%. The broken spores show much higher immunological activity comparing with original spores of Ganoderma lucidum.     

复合型生物絮凝剂处理低温低浊水影响因素

为探讨复合型生物絮凝剂(CBF)在处理低温低浊水源水过程中的影响因素,采用实验室静态试验方法,考察投加量、pH、阳离子絮凝剂等因素对絮凝效果的影响.结果表明:在单独使用CBF时,当投药量范围在5～17.5mg/L以内,CBF可有效地去除水中浊度与高锰酸盐指数(CODMn),最佳投加量为7.5mg/L.CBF在弱碱性条件下絮凝率较高,最佳pH为8.0.在混凝过程中投加阳离子絮凝剂可有效提高CBF对低温低浊水的处理效果并减少投药量.在与聚合氯化铝铁(PAFC)复配使用时,最佳投药量分别为4mg/L和10mg/L,此时浊度去除率为73.0%,CODMn去除率为60.7%.     

环境流体密度分层对浊流的流动和沉积的影响

基于雷诺平均的数学模型模拟研究环境流体密度分层与否条件下,2种入流机制的含多粒径颗粒物浊流由斜坡流至水平地形上的流动和沉积。结果表明:突然释放型浊流不论环境流体有无密度分层均在斜坡及水平地形前段形成沉积物波,而环境流体无密度分层的连续入流型浊流未出现波状沉积;自近源地区至远源地区沉积物粒径逐渐减小,但突然释放型浊流在波状沉积位置有大粒径沉积物,连续入流浊流沉积呈现更均匀的由上游至下游的自然粒径分选。     

Fragmentation Analyses of Granular Explosive Under Drop Weight Impact

Fragmental size and distribution of explosive particles play a more important role in the formation of hot-spot than original particles size under drop weight impact. Because the particles breakage and the hot-spots ignition will form in a sequence between fragments and between the fragments and the drop weight surface under the impact. In this paper, the size and distribution of the cyclotetramethylenete tranitramine(HMX) fragments were analyzed by the Laser Particle Size Analyzer Malvern MS2000. The post-analysis results of fragments showed that size distribution of fragments was strongly dependent on drop height. An empirical formula is established to describe the relationship between the average size and drop height. The volume-based probability distribution of explosive fragments was also studied by experiments and theoretical calculations.     

60Si2Mn弹簧钢碳化物快速球化工艺研究

从离异共析转变的原理出发,开发60Si2Mn弹簧钢的快速球化退火工艺.讨论加热温度对残留碳化物粒子数量和分布的影响规律以及残留碳化物粒子对碳化物快速球化的作用,研究冷却速度对相变模式的影响.结果表明快速球化退火中,加热温度过高,碳化物完全溶解,没有残留的碳化物作为后续形核核心,加热温度过低,片层状碳化物溶解、断裂不完全...