【作者】 梁爽；

【导师】 李星；

【作者基本信息】 北京工业大学 ， 土木工程， 2012， 博士

【摘要】 浸没式超滤（SUF）工艺在饮用水处理领域具有非常广阔的应用前景，可以有效地截留水中的颗粒物、藻类、病原微生物等，但对溶解性有机物的去除效果不佳，水中的天然有机物和藻类代谢物还会加重膜的污染。针对SUF工艺存在的问题，本研究构建了粉末活性炭/浸没式超滤一体化工艺（PAC/SUF），研究了该工艺对微污染含藻水中藻类和溶解性有机物的去除效能及影响因素，分析了工艺运行中的膜污染特性，通过在PAC/SUF工艺前设置不同的预处理工艺，考察了不同组合工艺在处理含藻原水时的效能及其适用性。PAC/SUF工艺对含藻原水中污染物去除效能的研究结果表明，在运行的前15天期间，氨氮去除效果由9.9%增加至81.5%，并逐渐趋于稳定；PCR-DGGE及测序结果表明，异养菌是PAC/SUF工艺中的优势菌种，去除NH3-N的蓝细菌和硝化螺菌属均有检出，表明PAC/SUF工艺中微生物量在富集，逐步形成了具有生物降解效能的PAC/SUF工艺。在整个运行期间该工艺对UV254、DOC和CODMn的平均去除率分别为32.7%、23.8%和33.2%，比SUF工艺提高了21.2%、8.8%和11.0%，说明PAC/SUF工艺有助于溶解性有机物的去除。对微囊藻毒素（MC-LR）、2-甲基异茨醇（2-MIB）和土臭素（Geosmin）等藻类代谢产物的平均去除率分别为43.0%、53.3%和61.0%，比SUF工艺提高了24.5%、21.8%和25.4%。对PAC/SUF工艺去除溶解性有机物机理的分析认为，超滤膜及其滤饼层的物理截留作用、PAC的吸附作用和生物降解作用是溶解性有机物的去除的三个主要因素。PAC/SUF工艺对嗅味物质的去除作用可分作三个阶段，第Ⅰ阶段平均去除率为70%，粉末活性炭吸附和曝气分别去除了50%和20%；第Ⅱ阶段为吸附、生物降解和曝气三方面均存在的过渡阶段，去除率为40%~60%；第Ⅲ阶段平均去除率为60%，生物降解和曝气分别去除了40%和20%。PAC/SUF工艺对芳香族蛋白、溶解性微生物产物（SMPs）和腐殖酸的去除效果明显优于SUF工艺，以PAC作为载体的微生物降解作用使得PAC/SUF工艺的混合液中EPS的类荧光蛋白和SMPs浓度显著低于SUF工艺，表明PAC可以强化SUF工艺对有机物的去除。扫描电子显微镜对膜表面和断面的观察结果表明，PAC/SUF工艺中膜表面的污染物主要由藻细胞、PAC和生物膜组成，比SUF工艺中膜表面的污泥层更为疏松，透水性更好，可以缓解膜污染。激光共聚焦显微镜的观察结果进一步证实了PAC/SUF工艺中膜表面存在由细菌和多糖等物质组成的厚度为20μm左右的生物膜，在一定程度上改善了对溶解性有机物的去除效果。针对一体化PAC/SUF工艺出水中MC-LR浓度不达标、2-MIB和Geosmin浓度高于嗅阈浓度以及原水中腐殖酸去除效率较低等问题，在PAC/SUF工艺前采用混凝-沉淀处理工艺以改善MC-LR、2-MIB和Geosmin的去除效果。结果表明，混凝沉淀工艺可以提高PAC/SUF工艺对有机物、MC-LR、2-MIB和Geosmin的去除效果，对芳香族蛋白、SMPs和腐殖酸去除效果的改善缓解了膜污染，但超滤出水中MC-LR、2-MIB和Geosmin仍有超标的现象发生。采用混凝-沉淀-砂滤常规工艺改善PAC/SUF工艺去除有机物的结果表明，常规工艺可以进一步强化有机物的去除效果，超滤出水MC-LR达到了《生活饮用水卫生标准（》GB5749-2006）的要求，2-MIB和Geosmin低于嗅阈浓度值10ng/L，其中砂滤对芳香族蛋白、富里酸和SMPs等溶解性有机物的去除效果显著，可更有效地缓解膜污染。采用高锰酸钾及研发的沸石负载高锰酸钾复合预氧化剂可以有效地去除藻类和MC-LR，但预氧化强化的常规工艺尽管可以提高有机物去除率，却不利于后续PAC/SUF工艺对有机物的去除，对MC-LR、2-MIB和Geosmin的总体去除率下降，超滤出水的MC-LR、2-MIB和Geosmin均不能达标。对藻类产生的膜污染进行膜清洗的结果显示，物理清洗不能有效清除膜表面的污染物，化学清洗方法中采用0.5g/L的氢氧化钠和0.5%体积浓度的双氧水依次浸泡30min的膜清洗效果最好。EEM分析表明，氢氧化钠可将膜表面附着的类荧光蛋白和溶解性微生物产物（包括多种蛋白和多糖）洗脱下来。原水水质和工艺运行条件均对膜污染有影响，TMP的增长速度与藻细胞浓度和膜通量均成正比，与反洗频率成反比；曝气频率与TMP的增长速度成反比，但影响程度不大，因此在确定PAC/SUF工艺运行条件时，需要综合考虑膜污染、产水量以及能耗等方面因素。更多还原

【Abstract】 In view of high removal efficiency of the submerged ultrafiltration (SUF)process to particle material, algae cells and pathogenic micro-organisms, this processhas been considered as the core unit of the current and future water treatmentprocesses. Unfortunately, in one hand, the SUF process cannot remove the dissolvedorganic matter (DOM) efficiently; in the other hand, the natural organic matter (NOM)and algogenic organic matter (AOM) in raw water will pollute the membraneseriously. In this thesis, a novelty integrated process of powered activatedcarbon/submerged ultrafiltration (PAC/SUF) has been developed to treatment themicro-polluted algal-rich raw water. The removal efficiency and mechanism of algaecells and DOM by the PAC/SUF were investigated. Meanwhile, the property of themembrane fouling was studied. Furthermore, the PAC/SUF process was hybrided withseries of pretreatment processes according to the characteristics of raw water quality.In the first study, the PAC/SUF process was directly used to treatment algal-richraw water. The experimental results indicated that the removal rate of NH3-Nincreased rapidly from9.9%to81.5%within the starting15days, then stabilizedsubsequently; By the PCR-DGGE technology, the bacterial community in the reactorof PAC/SUF was analyzed. It was indicated that heterotrophic bacteria was thedominant species, however, the autotrophic bacteria including Cyanobacteria andNitrospira were also detected, which were responsibility for NH3-N removal. In thewhole running period, the PAC/SUF process could remove DOM efficiently. Theaverage removal rate of UV254, DOC and CODMnwere32.7%,33.8%and33.2%,respectively, which increased by21.2%,8.8%and11.0%compared with the SUFprocess. Specifically for AOM, including MC-LR,2-MIB and Geosmin, the averageremoval rate could reach43.0%,53.3%and61.0%, respectively, which alsosignificantly increased by24.5%,21.8%and25.4%compared with the SUF process.Through a mechanism analysis of DOM removal, it was thinking that the physicalinterception of membrane and the gel layer on the surface of membrane, adsorption ofPAC and biodegradation contributed into the three main sources of DOM removal.Further analysis indicated that during the whole running period the removal of thetaste and odor matter could be divided into three stages. In the first stage, the averageremoval rate reached to70%, in which adsorption of PAC and aeration contributed50%and20%, respectively; In the second stage, the removal was contributed by thecombined action of adsorption, biodegradation and aeration, but the sharp decrease ofadsorption coupled with the immature biological function, led to a lower removal(40%~60%); In the third stage, the removal rate recovered to60%. Although thePAC was almost exhausted, the higher removal efficiency was contributed by the stable biodegradation function (40%) and aeration (20%).Three-dimensional fluorescence spectroscopy (EEM) was utilized to analyze themechanism of dissolved organics removal and the characteristics of membranefouling during the running period of the PAC/SUF process. Results showed that thePAC/SUF process could obtain much better removal efficiency of protein-likesubstances, soluble microbial by-products (SMPs) and humic-like substances than theseparate SUF process, which was attributed to PAC adsorption and biodegradation.The SEM was employed to observe the surface and cross-section of membrane. TheSEM photos showed that there was a porous cake layer composed by algal cells, PACand biofilm on the membrane surface in the reactor of PAC/SUF process. By theCLSM analysis, it was confirmed that the biofilm was composed of microbial cellsand polysaccharides. This cake layer was responsibility for the external membranefouling, however, it could refuse the high concentration of DOM in the reactor intothe membrane effluent.When the PAC/SUF process was used directly to treatment the algal-rich rawwater, the concentration of MC-LR,2-MIB and Geosmin in the membrane effluentusually can’t meet the Standards for Drinking Water Quality. In view of which,coagulation/sedimentation units were set as the pretreatment process of the PAC/SUFprocess. Results showed that coagulation/sedimentation units could improve organicremoval of the PAC/SUF process, especially for the removal of MC-LR,2-MIB andGeosmin. Additional, increased removal rate of protein-like substances, solublemicrobial by-products (SMPs) and humic-like substances in the raw water couldfurther help to mitigate membrane fouling. However, the concentration ofmicrocystin-LR,2-MIB and Geosmin still could not reach the standard.For further improving the running effect of the PAC/SUF process, theconventional water treatment process was utilized as the pretreatment units. Resultsshowed that the conventional treatment process contributed a further improvement onthe organic removal, with concentration of MC-LR,2-MIB and Geosmin in theeffluent meet the demand of Drinking Water Quality. As a result of sharp decrease ofprotein-like substances, soluble microbial by-products (SMPs) and fulvic after sandfiltration, membrane fouling was alleviated effectively. Enhanced coagulation withpotassium permanganate pre-oxidation was utilized to intensify the performance ofconventional pretreatment. Results showed that the pretreatment alleviated thedevelopment of TMP and enhanced the removal of dissolved organic matter. However,a poor organic removal by PAC/SUF was achieved. None of MC-LR,2-MIB andGeosmin in the effluent could reach the Drinking Water Quality. In order to reduce theload of water treatment processes, potassium permanganate loaded zeolite wasdeveloped and added into the algal-rich water as pretreatment, which was proved toremove the algae and the microcystins-LR effectively. Control measures on membrane fouling caused by algal-rich water wereinvestigated. Different chemical reagents were used to study the cleaning efficienciesof PVDF membrane after long–term ultrafiltration of algal-rich water. Results showedthat the physical methods could not remove the foulants availably, while the filterperformance of membrane soaked in0.5g/L of NaOH and0.5%of H2O2successivelyexhibited a best recover. SMPs (various protein and polysaccharide included) andprotein-like were redissolved in NaOH. Both of the quality of raw water and fluxexerted obvious influence on the membrane fouling. The growth of TMP wasproportional to either of the concentration of algal cells or the flux, but inverselyproportion to the frequency of air bubbling. However, mitigation of membrane fouling,energy depletion and operating cost should be taken into account comprehensively todetermine the optimal operating parameters.更多还原