Coagulation efficiency and flocs characteristics of recycling sludge during treatment of low temperature and micro-polluted water

Drinking water treatment sludge, characterized as accumulated suspended solids and organic and inorganic matter, is produced in large quantities during the coagulation process. The proper disposal, regeneration or reuse of sludge is, therefore, a significant environmental issue. Reused sludge at low temperatures is an alternative method to enhance traditional coagulation efficiency. In the present study, the recycling mass of mixed sludge and properties of raw water (such as pH and turbidity) were systematically investigated to optimize coagulation efficiency. We determined that the appropriate dosage of mixed sludge was 60 mL/L, effective initial turbidity ranges were below 45.0 NTU, and optimal pH for DOMs and turbidity removal was 6.5--7.0 and 8.0, respectively. Furthermore, by comparing the flocs characteristics with and without recycling sludge, we found that floc structures with sludge were more irregular with average size growth to 64.7 μupm from 48.1 μupm. Recycling sludge was a feasible and successful method for enhancing pollutants removal, and the more irregular flocs structure after recycling might be caused by breakage of reused flocs and incorporation of powdered activated carbon into larger flocs structure. Applied during the coagulation process, recycling sludge could be significant for the treatment of low temperature and micro-polluted source water.     

电磁场对污泥回流工艺混凝效能和絮体特性的影响

本研究采用电磁场对回流污泥进行磁化处理,考察了不同强度和时间电磁作用对污泥回流过程的混凝效果和溶解性有机物去除效能的影响.结果表明,磁化污泥可改善污泥回流混凝过程的浊度和DOC去除率,比磁化之前分别提高了3.7%、32.4%,足够大的磁场强度和必要的磁化时间对混凝效能改善有较显著的作用;磁化作用可使回流污泥和混凝时混合水的Zeta电位升高,使混凝时的絮体特性得到了明显改善,絮体具有更大的成长速率、平均絮凝指数和平均粒径,絮体结构更加密实、规则.     

超声对净水沉淀污泥絮体特性及对污泥回流效能的影响

为解决污泥回流强化混凝技术存在的有毒有害物质积累的问题,取净水沉淀污泥经超声预处理后进行回流试验,考察超声作用后净水沉淀污泥絮体特性的变化及其对回流效能的影响.结果表明:超声作用后污泥溶液的温度升高,絮体粒径减小,长时间作用后粒径可降至几个mm,且粒径与声能密度呈现相关性;1,5W/mL的超声处理后,絮体Zeta电位降低,比表面积增大,10,15W/mL的超声处理后絮体Zeta电位升高,比表面积有所下降;低声能密度(1W/mL)超声处理后污泥回流可强化混凝效果,30min超声作用后污泥回流的浊度、UV254和CODMn去除率分别提高了2.7%、23.12%和10.02%,长时间高声能密度(15W/mL)超声波处理污泥回流后混凝效果反而恶化.超声技术对污泥回流后污染物的去除率有一定的提高,但超声时间和声能密度必须很好控制.     

高密度澄清池除氟中试研究

以聚合氯化铝为混凝剂,采用高密度回流絮凝澄清池进行饮用水除氟试验。考察了原水水量、氟初始浓度、原水浊度、絮体回流比等因素对除氟效果的影响。结果表明:高密度澄清池具有良好的除氟效果,可使滤后水中氟浓度低于1 mg/L。当絮体回流点位于快速混合处时,回流比为50%时,能提高氟的去除率。     

三种常见混凝机理为主导条件下絮体特性研究

以模拟低浊微污染水为原水,硫酸铝[Al2 (SO4)3]为混凝剂,考察了3种常见混凝机理(电性中和、吸附架桥和网捕卷扫)为主导条件下絮体的成长过程、二维边界分形维数(Dpf)和比表面积及其与混凝效果的相关性.结果表明:吸附架桥为主导机理下絮体最大增长速率S (0.951)最快,达到稳定后絮凝指数FI最大(3.7%),二维边界分形维数Dpf最大(1.587),絮体呈块状且絮体间出现孔状间隙,比表面积介于网捕卷扫和电性中和之间[网捕卷扫(83.646m2/g)>吸附架桥(98.808m2/g)>电性中和(116.046m2/g)];FI值、S及Dpf变化与浊度去除率相关性较好,其相关系数分别达0.979、0.982和0.963,同时比表面积大的絮体吸附容量大,有机物的去除率高.     

Nano-TiO2回收过程中SO42-对不同混凝剂混凝过程的影响

为了降低纳米TiO₂使用成本,采用不同混凝剂对纳米TiO₂悬浊液进行固液分离.通过考察浊度去除率、出水pH值的变化情况,并结合X射线光电子能谱（XPS）、傅里叶红外光谱（FTIR）、固体核磁（NMR）、扫描电镜（SEM）及能谱分析（EDS）表征,探究了纳米TiO₂回收过程中SO₄^2-对不同混凝剂混凝过程的影响.结果表明,当使用AlCl₃作混凝剂时（0.1mmol/L）,SO₄^2-浓度从0.0mmol/L增加到20.0mmol/L,浊度去除率降低了0.80%,絮体粒径从450μm下降到215 μm,而强度因子无明显变化.低聚合态的Al_a不与SO₄^2-结合,混凝过程中通过吸附架桥和网捕卷扫的作用形成大量无定形的Al （OH）₃.当使用Al₁₃作混凝剂时,再生长后絮体的粒径随着SO₄^2-浓度的增加而下降,S-O峰的红移证明有新的含S聚合物产生,Al 2p的峰均向较高的结合能移动证明生成的絮体不是Al （OH）₃.     

生物絮凝剂用于给水混凝处理中浊度去除的研究

利用高岭土悬浊液和松花江原水作为研究对象,以混凝试验为基础考察了生物絮凝剂(BFs)对浊度的去除效果.结果表明,单独使用生物絮凝剂进行混凝处理在投药量5～19mg/L的范围内能够使高岭土溶液浊度去除84%,低于Al2(SO4)3(93%)和Fe2(SO4)3(94%). Zeta电位和混凝pH变化结果表明,生物絮凝剂的混凝效果主要受吸附架桥机理支配.向生物絮凝剂中投加少量的Al盐和Fe盐能够明显强化混凝效果,且在相同的混凝效果时Fe盐投加量小于Al盐投加量.这种强化作用主要是因为无机盐和生物絮凝剂的复合加强了电性中和与吸附架桥作用. Fe盐和生物絮凝剂复合使用可以在低投药量和中性pH条件下有效去除原水的浊度(94.6%).生物絮凝剂能够在较大的投药量范围内有效去除水源水中的颗粒物,形成的剩余污泥能够被自然降解;同时,由于不使用金属盐,大大降低了由于铝的积累而导致的致病风险,是一种环境友好的绿色絮凝剂.     

用粉末活性炭作前助凝剂提高PAC除藻效果的研究

采用烧杯搅拌实验研究了用粉末活性炭作前助凝剂提高聚合氯化铝(PAC)去除铜绿微囊藻的有效性。结果表明,单独使用粉末活性炭作前助凝剂的除藻效果并不好,而先投加20 mg/L高岭土,再将15 mg/L PAC与粉末活性炭同时投加,除浊除藻效果明显提高。考虑首先充分发挥粉末活性炭对有机物的去除能力,在除浊除藻率仍然较高的情况下,采用粉末活性炭先于高岭土2 min投加的方式,粉末活性炭的最佳助凝剂量为10mg/L。采用粉末活性炭、高岭土和FeCl3依次投加的完整助凝技术路线,除浊除藻效率最高。碱性水体比酸性水体有利于联用三种助凝剂除藻。扫描电镜(SEM)观察结果表明,采用助凝技术,藻细胞主要与高岭土无机颗粒发生凝聚,投加粉末活性炭有助于絮凝体体积增长,而在絮凝阶段投加FeCl3可使絮凝体的分维数达到1.947的最高值。联用粉末活性炭、高岭土和FeCl3是非常有效的助凝除藻新技术。     

Coagulation of micro-polluted Pearl River water with IPF-PACIs

Water samples collected from early March 2001 to the end of April 2002 at the branch of Pearl River around the Guangzhou City were analyzed for its micro-polluted characteristics. The coagulation behavior of polyaluminum chlorides(PACIs) was then examined focusing on the effect of primary water quality and speciation distribution. The results showed that PACIs exhibit better coagulation efficiency than alum in accordance with the different speciation.The turbidity removal property of PACIs is evidently better than alum at low dosage. While in neutral zone(about 6.5--7.5), the turbidity removal of PACIs decreases owing to the restabilization of particles at higher dosage. The organic matters in raw water exhibit marked influence on coagulation. In acidic zone, organic matters complex with polymer species and promote the formation of flocs. With an increase in pH, the complexation of organics with polymer species gradually decreases, and the removal of organics mainly depends on adsorption. The effect is evidently improved with the raise of B value.     

聚合氯化铝及聚合氯化铝铁处理微污染地表水效果

选用两种无机高分子混凝剂聚合氯化铝(PAC)和聚合氯化铝铁(PAFC),与传统混凝剂Al2(SO4)3处理微污染地表水。以浊度和CODMn去除率为主要指标,考察投药量和pH对混凝效果的影响。通过考察沉淀时间对浊度去除效果的影响,结合实验现象,讨论三种混凝剂生成矾花的大小和沉降性能。结果发现,PAC和PAFC在5mg/L的投药量下可以取得较好的混凝效果,出水符合GB 5749-2006《生活饮用水卫生标准》。三种混凝剂的最佳pH为6,PAFC受pH影响较小,当pH为5～8时可取得较好的CODMn去除效果。PAFC生成的矾花体积较大,沉降性能较好,在实际应用中可缩短沉淀池的水力停留时间。     

PAC与PDMDAAC复合混凝剂去除高浊度水中有机氯

以聚合氯化铝(PAC)和聚二甲基二烯丙基氯化铵(PDMDAAC)为原料制备复合混凝剂,采用强化混凝的处理方法,对高浊度水体中有机氯(OCPs)以及浊度去除效果进行研究.考察了PAC-PDMDAAC复合比例、复合混凝剂投加量、水样初始浊度、慢速搅拌时间、pH值等因素对浊度和OCPs去除效果的影响,结合絮体分形维数和Zeta电位对去除效果进行验证.结果表明,复合比例对处理高浊水体中的OCPs以及浊度效果影响较大,PAC与PDMDAAC复合比例为5:1,投药量为1mL/L,慢速搅拌时间为15min时,OCPs和浊度去除率达到最佳;随着初始浊度的升高,水体中OCPs的去除率也随之增加,表明PAC-PDMDAAC复合混凝剂更适用于高浊度水中OCPs和浊度的去除;复合混凝剂与其他混凝剂相比,其最佳pH值范围较广,当pH值为4时,OCPs和浊度去除率达到最佳.利用絮体分形维数和Zeta电位两种表征手段对混凝效果进行进一步探讨,说明了实验结果的正确性.     

壳聚糖改性粘土去除城市湖泊中藻类的研究

对壳聚糖改性粘土用于城市湖泊中藻类的絮凝去除进行了研究。实验表明,粘土经过壳聚糖改性后,对高藻水中藻细胞的去除效能得到很大的提高。相比单独投加壳聚糖,粘土的加入增加了絮体密实度,减少了絮体体积,并使絮体分布更均匀。在壳聚糖与粘土配比为1∶20时,叶绿素的去除率和浊度的去除率均为最佳。粘土的种类对除藻效果有一定影响,其中以高粘凹凸棒石为最佳,在最佳投加量28 mg.L-1时,对叶绿素的去除率达到96.2%;粘土的粒径对絮凝效果基本没有影响,在粒径为60μm与300μm之间改性粘土对藻细胞的凝聚效果是一致的。经壳聚糖改性的粘土在酸性条件下絮凝效果较好,当pH值大于7时,其絮凝能力迅速下降。     

强化混凝去除微污染湖泊水浊度及TOC的研究

通过烧杯混凝试验和动态连续混凝试验,就混凝剂种类、投药量、pH值、水温等因素,研究强化混凝对水中浊度和TOC去除效果的影响。试验结果表明:PAC最佳投量为30mg/L,浊度去除率为90.19%,TOC去除率为38.2%,水温高于20℃时,聚合氯化铝对浊度和TOC去除率分别高达84.95%、33.18%以上。虽然pH值是影响有机物去除的主要参数,动态连续混凝试验表明,不改变pH值,强化混凝工艺依然能极大地改善出水水质,滤后水质浊度为0.1NTU,TOC为6.23mg/L。     

Coagulation of micro-polluted Pearl River water with IPF-PACls

IntroductionThewaterqualityofnaturalriverisverycomplex,includingvariouskindsoforganic ,inorganicandbiologicalmatters,suchasthesolublemolecules,polymericmatters,colloids ,andsuspendedparticlessuchaslivebacteria ,algaeandalsoprotozoan (Tang,2 0 0 0 ) .Generally ,aquaticparticulatesaredispersivelysuspended ,ordepositintodiversesedimentsthroughadsorption ,aggregationandsedimentation.Furthermore ,theycanberesuspended ,transferredandconvertedundervariouswaterfluidconditions.Clearlydocumentedhistori…     

Polytitanium sulfate (PTS): Coagulation application and Ti species detection

Interest in the development of inorganic polymerized coagulants is growing; however, there are only limited studies on the synthesis of polytitanium coagulants, which are expected to exhibit improved coagulation efficiency with better floc properties. This study presents the synthesis of polytitanium sulfate (PTS) for potential application in water purification, followed by characterization of PTS flocs and titanium species detection. Stable PTS solutions were successfully synthesized and standard jar tests were conducted to evaluate their coagulation efficiency. Electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) speciation analysis revealed that a variety of mononuclear and polynuclear complexes were formed in PTS solution, indicating the polymeric nature of the synthesized coagulant. Floc characteristics were studied through on-line monitoring of floc size using a laser diffraction particle size analyzer. Results showed that PTS had a comparable or in some cases even higher organic matter and particulate removal efficiency than Ti(SO₄)₂. The effluent pH after PTS coagulation significantly improved toward desirable values closer to neutral pH. Properties of flocs formed by PTS were significantly improved in terms of floc size, growth rate and structure. This study showed that PTS could be an efficient and promising coagulant for water purification, with the additional benefit that its coagulated sludge can be used to recover valuable TiO₂ nanoparticles for various commercial applications.     

聚硅酸硫酸铁强化混凝去除微污染水源水中天然有机污染物

应用强化混凝技术,降低原水中有机物含量,是控制消毒副产物生成的有效途径之一。通过混凝搅拌试验,评价了聚硅酸硫酸铁混凝剂对原水中有机污染物的去除效果,考察了混凝剂投加量、pH值等对去除效果的影响。结果表明：聚硅酸硫酸铁去除有机物和除浊能力明显优于硫酸铁、聚合硫酸铁,其适宜的投药量范围和pH值范围宽;聚硅酸硫酸铁在混凝过程中形成的矾花较大,沉降速度快,因而可缩短处理水在构筑物中的停留时间,提高系统的处理能力;此外,通过正交实验确定了聚硅酸硫酸铁混凝剂的最佳水力条件。     

Evaluation of reusing alum sludge for the coagulation of industrial wastewater containing mixed anionic surfactants

A coagulation-flocculation process is typically employed to treat the industrial wastewater generated by the consumer products industry manufacturing detergents, soaps, and others. The expenditure of chemicals including coagulants and chemicals for pH adjustment is costly for treating this wastewater. The objective of this study was to evaluate the feasibility of reusing the aluminum sulfate (alum) sludge as a coagulant or as a coagulation aid so that the fresh alum dosage can be minimized or the removal e ciency can be enhanced. The experiments were conducted in a jar-test apparatus simulating the coagulation-flocculation process for simultaneous removals of organic matters, anionic surfactants, suspended solids, and turbidity. At the optimum initial pH value of 10 and the fresh alum concentration of 400 mg/L, the total suspended solids (TSS), total chemical oxygen demand (TCOD), total anionic surfactants, and turbidity removal e ciencies were 71.5%, 76.4%, 95.4%, and 98.2%, respectively. The addition of alum sludge as a coagulant alone without any fresh alum addition could significantly remove the turbidity, TCOD, and anionic surfactants. The TSS was left in the supernatants after the settling period, but would subsequently be removed by adding the fresh alum. The TSS, TCOD, and turbidity removal e ciencies were also enhanced when both the alum sludge and the fresh alum were employed. The TCOD removal e ciency over 80% has been accomplished, which has never fulfilled by using the fresh alum alone. It is concluded that the alum sludge could be reused for the treatment of industrial wastewater generated by the consumer products industry.     

微气泡及其产生方式对活性污泥混合液性质的影响

微气泡曝气有助于强化氧传质过程,在废水好氧生物处理中具有潜在的应用优势;同时,微气泡及其产生方式可能对污泥混合液性质产生影响.本研究采用SPG膜微气泡发生系统研究了微气泡及其产生方式对污泥混合液性质的影响.结果表明,微气泡曝气中,微气泡附着于污泥絮体导致污泥上浮聚集,从而造成反应器中污泥浓度(MLSS)下降,以及污泥沉降性能变差.微气泡产生过程中,液体循环泵(离心型)产生的强水力剪切力作用于污泥混合液,造成污泥絮体破碎、污泥粒径减小以及污泥絮体EPS释放,进而使得上清液浊度和有机碳(特别是胶体有机碳)浓度升高,污泥絮体的再絮凝能力丧失.微气泡产生过程中,污泥破碎导致的污泥有机物的释放使得污泥混合液的黏度增加,但混合液表面张力保持不变.     

铝基无机有机复合絮凝剂对超滤膜性能的影响研究

采用铝基无机有机复合絮凝剂(PAC-JY01)对含有腐殖酸与高岭土的模拟水样进行强化混凝处理,取混凝后出水进行超滤,通过测定超滤前后出水水质以及超滤膜运行状况,探讨PAC-JY01对超滤膜工艺效能的影响.结果表明,在强化混凝-超滤联用工艺中PAC-JY01的最佳投加量为3mg/L,最佳pH=6.在最佳条件下,UV254和浊度的去除率分别达到79.30%、99.70%;在实验运行条件下,较大的絮体容易在膜表面沉积而造成膜污染.     

Coagulation behavior and floc properties of compound bioflocculant-polyaluminum chloride dual-coagulants and polymeric aluminum in low temperature surface water treatment

This study was intended to compare coagulation behavior and floc properties of two dualcoagulants polyaluminum chloride–compound bioflocculant(PAC–CBF)(PAC dose first) and compound bioflocculant–polyaluminum chloride(CBF–PAC)(CBF dose first) with those of PAC alone in low temperature drinking water treatment. Results showed that dualcoagulants could improve DOC removal efficiency from 30% up to 34%. Moreover, CBF contributed to the increase of floc size and growth rate, especially those of PAC–CBF were almost twice bigger than those of PAC. However, dual-coagulants formed looser and weaker flocs with lower breakage factors in which fractal dimension of PAC–CBF flocs was low which indicates a looser floc structure. The floc recovery ability was in the following order:PAC–CBF PAC alone CBF–PAC. The flocculation mechanism of PAC was charge neutralization and enmeshment, meanwhile the negatively charged CBF added absorption and bridging effect.