【作者】 王娜；

【导师】 马军；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2012， 博士

【摘要】 腐殖质是饮用水水源中常见的有机成分，腐殖质的存在一方面使饮用水处理工艺的工作效率降低；另一方面，在以有毒有害等污染物为主要去除对象时，腐殖质影响到对目标污染物的去除效果。鉴于天然水环境中腐殖质具有络合性和还原性的双重性质，其存在会对吸附和氧化反应体系带来影响，因此，研究腐殖质与其它微污染成分以及水处理中常用药剂之间的相互作用，对于提高水处理除污染效率有重要意义。本文首先研究了腐殖质的凝聚特性，为深入掌握颗粒的吸附凝聚机理及污染物的吸附去除机制提供理论基础，在此基础上开展了低温、低浊、高色水的二次加药强化混凝实验以及地表水不同前处理工艺对PVDF微滤膜污染的影响研究；然后以腐殖质为主要背景成分，进行了预氧化强化去除痕量还原性毒物As(III)和Tl(I)的研究；最后通过对典型天然有机物(NOM)污染水源的中试研究，考察了其处理特性及强化混凝效果。通过纳米粒度仪检测了不同水化学参数(pH值、Ca2+离子浓度)时腐殖质颗粒的粒度变化和Zeta电位变化，实验结果很好地反映了腐殖质的凝聚特性。三维荧光光谱分析显示出相同UV254浓度条件下富里酸(FA)比腐殖酸(HA)具有更多的反应官能团，这与二者不同的凝聚特性相吻合。配位络合反应是腐殖酸和富里酸发生凝聚的基础，Ca2+离子的络合作用明显导致腐殖酸和富里酸悬浮液颗粒的粒度增加、Zeta电位升高；其中，在pH值9.0~6.0的范围，腐殖酸与Ca2+离子的络合作用强烈、颗粒的凝聚现象明显；而富里酸中由于含有较多的可离解负电性官能团，官能团之间相互排斥，Ca2+离子的络合作用受到一定抑制，因此不利于“负电性降低”及颗粒凝聚。实验结果显示出降低初始pH值更有利于富里酸凝聚的发生。当初始pH值从9.0降至6.0，FeCl3水解颗粒的Zeta电位从-7mV上升至+24mV，颗粒的平均直径从1100nm降低至300nm；Ca2+与铁盐水解颗粒表面的官能团发生专属结合，使铁盐水解颗粒的Zeta电位上升、粒度略有增加。憎水性NOM的空间稳定机理是抑制低碱度、低浊度、高色水混凝的主要原因，二次投药混凝可有效地促进絮体形成。络合反应是腐殖酸、富里酸臭氧氧化生成物凝聚的关键。少量的臭氧可促进其腐殖酸和富里酸与Ca2+离子络合，使络合物的粒度增加；臭氧过量投加会使络合物的粒度降低。PVDF微滤实验表明有机或无机颗粒的化学吸附凝聚可造成PVDF膜通量显著下降,水中污染组分与膜之间的“吸附性能”影响到膜污染的恢复。天然有机物的臭氧氧化产物与Ca2+离子有较强的络合能力，在微滤运行压力下形成致密的表面凝胶层，使膜通量显著下降，其膜污染层中钙元素的相对含量为11.10%，明显高于未经氧化的水样。对于滤池反洗废水，其中的絮体容易被膜物理截留，膜反洗效果较好。实验室配水开展的研究表明，在天然水环境pH下，As(V)与Fe3+离子及其水解产物有很强的络合能力，容易通过FeCl3混凝去除，共存的Ca2+离子、腐殖酸、HCO3-离子对络合位的竞争能力较弱。腐殖酸在氧化剂O3和KMnO4氧化As(III)的过程中竞争能力均很弱，As(III)会被优先氧化，腐殖酸存在对预氧化强化混凝去除As(III)的影响不明显。臭氧和高锰酸钾预氧化均能强化FeCl3混凝对Tl(I)的去除，但强化机理不同。臭氧可使Tl(I)氧化成络合能力更强的Tl(III)，并且铊的去除率与O3投量成正相关；Ca2+离子浓度较高时，会对O3氧化生成的Tl(III)的吸附络合存在一定竞争；共存的腐殖酸有很强的竞争消耗氧化剂臭氧能力，少量腐殖酸存在时Tl(I)就很难被O3氧化。在天然水pH条件下，KMnO4不能将Tl(I)氧化成Tl(III)，Tl(I)的强化去除在于被原位生成的MnO2·mH2O吸附去除；少量Ca2+离子的存在就会显著地抑制Tl(I)在MnO2·mH2O表面的吸附；腐殖酸及其氧化产物对Tl(I)在MnO2·mH2O的吸附有一定的抑制。在腐殖酸存在的水质条件下，KMnO4-O3联合预氧化是去除痕量铊的有效措施，O3和KMnO4的投加量均很小(UV254=0.08cm-1时，0.8mg/L KMnO4+1.25mg/L O3使去除率提高30%)，KMnO4将腐殖酸中还原性组分氧化破坏后，可以使臭氧有效地发挥对Tl(I)的氧化作用。天然有机物的组成和性质对强化混凝效果有重要影响。混凝剂投量主要由腐殖质的含量决定，与UV254值有较好的对应性，不能仅通过TOC值来判断。当原水NOM浓度高时，气浮出水的大颗粒(>5m)比例升高，并导致过滤效率降低、过滤周期缩短。憎水性腐殖质组分是臭氧反应的活性组分，其含量的差异导致臭氧的强化混凝效果不同。原水中溶解性腐殖质含量多时，臭氧强化混凝效果较差；反之，效果显著。对藻类等大颗粒成分，臭氧有较好的强化去除效果；仅依靠提高混凝剂投量，通过网捕卷扫对藻类物质的强化去除有限。臭氧预氧化使气浮出水中氯仿的生成势降低，但也导致溴仿的生成势明显升高。色质联机检测结果显示，混凝对含不饱和键的醇类(烃类)有较高的去除率，而对低分子烃(或醇)的去除率较低，臭氧氧化可提高低分子烃(或醇)类物质的去除率。更多还原

【Abstract】 Humic substance (HS) is commonly present in source waters. On one hand, itreduces the treatment process efficiency; on the other hand, it may act actively duringwater treatment and may influence the removal of hazardous pollutants. As both acomplexing and reducing agent, it may affect the adsorption and oxidation system.Thus, it is fundamental and necessary to study the interaction mechanism among thehumic substances, the micro-pollutants, and the water treatment agents. This paperfirstly studied the aggregation property of humic substances as to provide insight intothe mechanism of pollutant adsorption and particle aggregation, on this basis, westudied the influence of HS on coagulation and PVDF microfiltration membranefouling. Then we studied the removal of reducing hazardous material As(III) and Tl(I)by oxidation, and analyzed the influencing factors on the removal performance ofthese pollutants. We also studied the effect of ozone pre-oxidation on the treatmenteffectiveness of natural organic matter polluted waters using a pilot scale treatmentsystem.The variation of particle size and Zeta potential changes detected by MalvenNano Zetasizer may indicate the extent of aggregation of particles. The three-dimensional fluorescence spectrum results showed that fulvic acid (FA) has morefunctional group than humic acid (HA), thus lead to different aggregation property.Complexation is the basis for HA and FA aggregation, and their complexation withCa2+was the main reason for the increase of particle size and Zeta potential. In thepH range of6.0~9.0, the complexation of Ca2+with HA is strong, and the extent ofparticle aggregation is remarkable; while in the case of FA, it had more functionalgroups, their inter repulsion suppressed the Ca2+complexation, which is unfavorablefor lowering the negative charge and thus causing aggregation. Ozonation increasedHA’s acidic functional group, and the oxidation products aggregated due to hydrogenbonding, and the particle size was increased. With the decreasing of pH from9.0to6.0, the average Zeta potential of the Fe-hydrolyzed species increased from-7to+24and the main particle average diameter decreased from1100nm to300nm. Ca2+cation may complex with the functional groups on the Fe-hydrolyzed species’ surface,and made the particle Zeta potential more plus and the particle size increase slightly.The sterical stabilization mechanism of hydrophobic NOM adsorbed on Fe(OH)3(s)was the main reason inhibiting the coagulation of low alkalinity, low turbidity andhigh NOM water, and “two-stage coagulation” could promote the formation of flocs effectively.Complexation was the key factor for the aggregation of ozone oxidationproducts of HA and FA. At low ozone dose, ozone could increase the acidicfunctional group and improve the complexation between ozone and Ca2+, and the sizeof the complexed particles was increased; but at high ozone dose, ozone may reducethe molecular weight of organics, and the size of the complexed particles wasdecreased. The chemical adsorption and aggregation of organic or inorganic particlesmight significantly reduce the PVDF membrane flux. Whilst the adsorbability of thepollutants with the membrane influenced the membrane’s cleaning effect and the fluxrecovery extent. The ozonation products of NOM had stronger complexing abilitywith Ca2+, which aggregated under the micro-filtration pressure, and led to theincrease of particle removal and the evident decrease of membrane flux. The Caelement content of the foulants on membrane surface was11.1%with the case ofozonated water, which was clearly higher than the case of unozonated water. Withthe sand filter backwash water, it contained aggregates that had weak attachmentwith the membrane, thus the membrane flux was easily recovered after flush.The experiment using simulated water showed that under natural pH condition,As(V) had strong complexing ability with Fe3+or the hydrolyzed species, As(V)could be easily removed by coagulation, and the impact of the competing Ca2+,humic acid, and HCO3-was weak. During the oxidation of As(III) by both O3andKMnO4, the oxidant competing ability by humic acid was very weak, and the impactof humic acid on As(III) removal by preoxidation-coagulation was not obvious.The complexing ability of Tl(I) was very week, while Tl(III) had goodcomplexing ability. Both O3and KMnO4could promote Tl(I)’ removal in FeCl3coagulation, but the mechanism was different. Ozone could oxidize Tl(I) into Tl(III),and the thallium removal effectiveness was related to the ozone dosage. When theCa2+concentration was high, it would compete the complexing site with Tl(III);humic acid had strong competing ability for O3, and a low dose of humic acid wouldprevent the oxidation of Tl(I) by O3. Under natural pH condition, KMnO4could notoxidize Tl(I) into Tl(III), the increased removal efficiency was due to the goodadsorption by in-situ formed MnO2·mH2O; a low dose of Ca2+significantlyinhibited Tl(I)’ adsorption on MnO2·mH2O; the presence of humic acid mightinfluence Tl(I)’ adsorption on MnO2·mH2O. Since both O3and KMnO4had strengthand weakness during the enhancement of Tl(I) removal, combined oxidation by O3and KMnO4was efficient for Tl(I) removal, and lower dose of these oxidants wasrequired, ozone could efficiently oxidize Tl(I) after KMnO4destroy the reducingfunctions of humic acid. The property of NOM had great influence on the enhanced coagulation ofparticles such as algae and inorganic particles. The coagulant dose was mainlydetermined by the hydrophobic fraction of NOM, and had better correlation withUV254than with TOC. When the NOM concentration was high, the ratio of larger particles(>5m) in the DAF effluent increased, and for larger particles, the major filtrationmechanism changed to physical straining and wedging, the filtration efficiencydecreased and the filter run time is reduced. Hydrophobic fraction of NOM wasactive component in ozonation, its difference in the content in water led to differentozonation effect. With the raw water containing high hydrophobic substance, the pre-ozonation on the enhanced coagulation was less effective; conversely, the pre-ozonation effectiveness was obvious. Preozonation was efficient for algal particlesreduction, and it was not effective with just increasing the coagulant dose. Pre-ozonation reduced the chloroform formation potential, but increased the chloroformformation potential. The GC-MS results showed that coagulation was efficient for theremoval of alcohols and hydrocarbons with unsaturated links, but not effective forthe removal of hydrocarbons and alcohols with low molecular weight, and pr-ozonation improved their removal.更多还原