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题名: 紫外与氯联合消毒的饮用水管网水质转化研究
作者: 朱莹
学位类别: 博士
答辩日期: 2015-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 胡春
关键词: 饮用水,UV/Cl2消毒,管网水质,生物膜,反硝化菌,Drinking water, UV/Cl2 disinfection, Distribution system water quality, Biofilm, Nitrate reducing bacteria
其他题名: Transformation of water quality in drinking water distribution system with sequential disinfection of UV and Cl2
学位专业: 环境工程
中文摘要:     饮用水处理过程中,传统的氯消毒在控制管网中微生物生长的同时会增加消毒副产物(DBPs)的生成风险。近年来,紫外(Ultraviolet,UV)消毒逐渐引起人们关注。通常情况下紫外和氯联合应用于饮用水消毒。了解紫外与氯(UV/Cl2)联合消毒对管网水质转化的影响对饮用水水质安全保障具有重要意义。本论文以北方某自来水厂地表水和地下水为研究对象,采用环状生物膜反应器模拟管网,系统研究了 UV/Cl2联合消毒的饮用水管网中水质及微生物群落结构变化情况,主要研究内容和结果如下:
    (1)紫外照射对天然有机物结构及后续氯消毒副产物生成的影响
    从水库底泥中提取天然有机物(NOM),根据亲疏水性的不同分级成腐殖酸(HA)、富里酸(FA)和富里酸亲水(FAHPI)部分,以市售 HA和  FA作为对照,通过高效凝胶色谱(HP-SEC)、红外光谱(FT-IR)表征以及氯消耗实验确定 NOM 中氯反应活性位点,研究低(中)压紫外照射对 NOM中反应活性位点及后续 DBPs 生成的影响。研究结果表明底泥中提取的疏水性 HA的氯反应活性基团是芳环、甲基、愈创木基木质素基团,DBPs的生成以三氯甲烷(TCM)为主;而底泥中提取的 FA和  FAHPI的氯反应活性基团是酚羟基,DBPs的生成以二氯乙酸(DCAA)为主。UV照射可以降低NOM疏水性和TCM生成量,增加 NOM亲水性和  DCAA生成量。相同剂量的中压  UV照射对NOM结构及DBPs生成的影响较低压紫外照射大。
    (2)饮用水 UV/Cl2联合消毒对管网中消毒副产物转化的影响
    通过UV/Cl2联合消毒管网和单独氯消毒管网对比,监测两种不同消毒方式下管网进出水中三卤甲烷(THM4)和卤乙酸(HAA5)浓度变化。采用三维荧光、电化学、焦磷酸测序等分析方法表征管网进出水中DBPs浓度和有机物结构变化以及管网腐蚀过程、管垢生物膜上微生物群落结构特征。研究结果表明在不同管网运行阶段,管网出水中THM4和HAA5浓度较进水中减少。在快速腐蚀阶段,UV/Cl2消毒管网中腐蚀速率及THM4和HAA5减少率均高于单独氯消毒管网;而腐蚀稳定阶段,单独氯消毒管网中腐蚀速率及THM4和HAA5减少率均高于 UV/Cl2消毒管网。而在不同运行阶段,UV/Cl2消毒管网管垢生物膜中脱卤菌含量均低于Cl2消毒管网。管网中消毒副产物转化是微生物与化学过程协同作用结果。紫外预处理降低氯消毒管网腐蚀速率同时降低管网中三卤甲烷及卤乙酸转化率。
    (3)UV/Cl2消毒强化腐蚀层形成的地表水管网腐蚀和微生物群落结构特征
    以地表水为研究对象,通过扫描电镜( SEM)、X-射线衍射(XRD)、电化学、定量PCR(qPCR)和焦磷酸测序Pyrosequencing)等分析方法,表征管网腐蚀、管垢物相结构、管垢生物膜中微生物群落结构特征,探讨采用UV/Cl2联合消毒强化腐蚀层形成的地表水管网中管网腐蚀及微生物群落结构特征。结果表明,UV/Cl2消毒管网中,UV预处理可以减少氯消毒管网中氯消耗,并抑制拉森指数升高带来的管网出水铁释放和浊度增加。定量 RCR、焦磷酸测序和主成份分析结果表明UV预处理可以诱发氯消毒管网管垢生物膜中反硝化菌Dechloromonas  sp.成为优势菌,微生物驱动的铁氧化还原循环进一步抑制UV/Cl2消毒管网的腐蚀,而单独  Cl2消毒管网中分泌铁载体的微生物抑制腐蚀效果较反硝化菌低。
    (4)UV/Cl2消毒模拟实际条件的管网腐蚀和微生物群落结构特征
    以地下水和地表水为研究对象,通过定量PCR(qPCR)和焦磷酸测序(Pyrosequencing)分析,表征管网进出水及管垢生物膜的微生物群落结构及条件致病菌分枝杆菌(Mycobacterium  sp.)含量变化。研究结果表明不经过低氯生物膜培养阶段,UV与高浓度氯抑制管网中总细菌及铁循环菌生长,管网生物膜对腐蚀抑制作用减弱,腐蚀速率加快。消毒剂可以有效控制管网出水中条件致病菌分枝杆菌(Mycobacterium sp.),但对管垢生物膜中分支杆菌抑制效果不明显。

 
英文摘要:     Chlorination  has been  considered  as a  cost-effective  approach for  inactivating waterborne pathogens in  drinking water treatment (DWT), However,  chlorine reacts with   natural  organic   matter   (NOM)   to  form   a   variety   of  toxic   disinfection by-products   (DBPs).    Recently,   ultraviolet    irradiation   has   gained    increasing application  as  a  primary  disinfectant  in   DWT,  followed  by  chlorination.  While effects of UV/Cl2  treatment on the transformation of  water quality in drinking water distribution system (DWDS)are unclear. In this scenario,annular reactors (ARs) were installed to simulate  the DWDS, with the  carbon-filtered water and ground water  as the raw  water. Tranformation  of water  quality in  DWDS  with UV/Cl2   disinfection were systematically investigated. The main conclusions were as follows.
    (1) UV effects on NOM structure and subsequent DBPs formation
    Sediment-derived humic acid  (HA), fulvic acid (FA)  and hydrophilic fraction of fulvic   acid   (FAHPI)   samples   were   utilized   in   UV   irradiation   followed   by chlorination,   with   the    commercial   humic   substances   for    comparison.   High performance  size  exclusion  chromatography  (HP-SEC),fourier  transform  infrared spectroscopy (FT-IR)  and chlorine  decay  were utilized  to characterize  the reactive groups toward chlorine.  UV effects on  the reactive groups  of NOM and subsequent DBPs formation  were evaluated.  It was  found that  FA and FAHPI  samples mainly consisted  of  ester,  phenolic  hydroxyl  and  aromatic  ketone  groups,  among them,phenolic hydroxyl groups were highly reactive  with chlorine, forming dichloroacetic acid  (DCAA) during  chlorination.  While HA  samples mainly  contained  aromatic, methyl  and guaiacyl  lignin  groups, which  were  reactive toward  chlorine,  forming trichloromethane   (TCM).  UV   irradiation  eliminated   the  aromatic,   methyl   and guaiacyl  lignin  groups,  depressing  TCM  formation  during  post-chlorination   and increased   phenolic  hydroxyl   groups,   enhancing   subsequent  DCAA   formation. Medium pressure UV light generally exerted greater impacts on  NOM structures and subsequent DBPs formation than corresponding low pressure UV light did.
    (2)   Effects  of   UV/Cl2   treatment   on   DBPs  transformation   in   drinking   water distribution system
    Annular  reactors  (ARs)   equipped  with  cast   iron  coupons  were  installed   to simulate the  DWDS. THM4  and HAA5  concentrations in  influents and effluents  of AR  with  UV/Cl2  and  AR  with  Cl2  were  monitored.  Excitation  emission  matrix (EEM), electrochemistry analysis  and pyrosequencing were  used to characterize the orgnic  matters  in  influents  and   effluents  of  ARs,  corrosion  rate  and  biological community in  biofilms.  It was  found that  both  THM4 and  HAA5 concentration  in effluents of two  ARs were decreased  as compared with that  in influents at  different running stages.  At stage  I, corrosion rate  and DBPs  reduction ratio in  the AR  with UV/Cl2 were  higher  than that  in the  AR with  Cl2,  while corrosion  rate and  DBPs reduction ratio  in the  AR with Cl2  were higher  than that in  the AR  with UV/Cl2  at stage  II. Pyrosequncing  resutls  showed  that relative  abundance  of dehalogenating bacteria in the biofilm of AR with Cl2 was higher than  that in the biofilm of AR with UV/Cl2at different  running stages.  Reduction  of DBPs  was influenced  by both  the biological and chemical porcesses in DWDS.
    (3) Characterization  of corrosion and  biological community in  corrosion-reinforced surface water DWDS with UV/Cl2  disinfection
    Surface water  was used to simulated  the DWDS. Scanning  electron microscopy (SEM),  X-ray  diffraction  (XRD),  electrochemistry   analysis,  realtime  fluorescent quantitative-PCR  (qPCR)  and   pyrosequencing  were  utilized   to  characterize  the corrosion rate, corrosion scales and biological commuinty of bioflims in the AR with UV/Cl2 and  AR with  Cl2. It  was found  that UV pretreatment  not only  reduced the required  initial chlorine  dose,  but  also  inhibited the  iron  release  and turbidity  of effluents  resulting  from  the increase  of  the  Larson-Skold  Index  (LI)  of drinking water.  It   was  verified  that   UV/Cl2  disinfection   denitrifying  functional  bacteria advantage in  the biofilm  of corrosion  scales in  drinking water  distribution system. Principal  component  analysis  indicated  that  the  nitrate-reducing   bacteria  (NRB) Dechloromonas  exhibited  the greatest  corrosion  inhibition  by  inducing the  redox cycling of iron to enhance  the precipitation of iron oxides and formation of  Fe3O4  in the  AR with  UV/Cl2,  while the  rhizobia  Bradyrhizobium and  Rhizobium,  and the NRB Sphingomonas, Brucella producing siderophores had weaker corrosion-inhibition effect by capturing iron in the AR with Cl2.
    (4) Characterization of  corrosion and biological  community in DWDS  with UV/Cl2 disinfection under physical running condition
    Ground  water  and   carbon-filtered  surface  water  was   used  to  simulated  the DWDS.  Realtime  fluorescent quantitative-PCR  (qPCR)  and  pyrosequencing  were utilized   to   characterize   total   bacteria,   opportunistic   pathogen   and   biological communities  in   the  influents,  effluents   and  biofilm   of  two  ARs.It   was  found thatsequential disinfection with UV and high  chlorine prevented the accumulation of biomass within the AR, preventing the formation of protective layer, resulting higher corrrosion  rate  in   the  AR  with  UV/Cl2   than  that  with  Cl2   alone.  In  addition, disinfectant could better control  Mycobacterium sp. (opportunistic pathogen) in bulk water than that in biofilms.

 
 
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/34487
Appears in Collections:环境水质学国家重点实验室_学位论文

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Recommended Citation:
朱莹. 紫外与氯联合消毒的饮用水管网水质转化研究[D]. 北京. 中国科学院研究生院. 2015.
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