RCEES OpenIR  > 环境水质学国家重点实验室
Alternative TitleEffects of water source quality on stability of iron corrosion in distribution systems
Thesis Advisor胡春
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Discipline环境科学
Keyword铁腐蚀 地下水 地表水 氯胺 微生物腐蚀 Iron Corrosion Groundwater Surface Water Chlorine Chloramine Microbially Influenced Corrosion
Abstract     水资源短缺是全球众多城市面临的严重问题,很多城市实施水源切换工程以缓解供水压力。而水源切换过程中,给水管网进水水质发生改变时,可能由于铁腐蚀产物释放增加而导致管网“黄水”的发生。本论文以北方某城市自来水厂地下水和地表水为研究对象,在管网模拟系统、生物膜反应器等多种模式下,结合扫描电镜(SEM)、X-射线衍射仪(XRD)、基因扩增-变形梯度凝胶电泳(PCR-DGGE)以及高通量测序等手段,研究了不同水源水质下的腐蚀过程以及关键水质参数对腐蚀稳定性的影响,以指导可行的水质调控方案的实施。主要研究结果如下:
(1)以北方某城市发生和未发生“黄水”区历史给水铸铁管段为研究对象,探讨了水源切换条件下“黄水”释放机制。结果表明,未发生“红水”区地表水管段消毒剂消耗少,水质稳定,垢层主要由α-FeOOH,Fe3O4和γ-FeOOH组成,垢内微生物以铁还原菌(IRB)Geothrix  sp.为主,并伴随少量的铁氧化菌(IOB)Gallionella sp.。“黄水”发生区地下水管段消毒剂消耗较多,出水浊度高,管垢以-FeOOH为主,垢层内微生物以IOB   Gallionella   sp.和Sediminibacterium sp.为主。添加消毒剂运行后,地下水管段出水渐趋稳定,铁离子释放少,垢层中 IRB出现并成为优势菌。腐蚀层中IOB和IRB的协同作用可以降低铁离子的释放从而减缓“黄水”的发生。
(2)使用市售新铸铁管进行模拟实验,研究了不同水源中铁管的腐蚀机制。地下水管网中腐蚀产物主要以疏松的α-FeOOH为主,BET比表面积为85.5 m2g-1;地表水管网中腐蚀产物较致密,以晶形良好的 α-FeOOH、Fe3O4和CaCO3为主,相应的 BET比表面积为18.8 m2 g-1。在硝酸盐浓度为  5~7.9 mg N L-1的地下水管网中,腐蚀稳定性主要受依赖于硝酸盐还原菌(NRB)和 IOB驱动的二价铁氧化影响;在含较低浓度硝酸盐(0.9~2.2 mg N L-1)的地表水管网中,腐蚀主要受  NRB厌氧呼吸诱导的铁氧化还原循环影响。上述结果在生物膜反应器中也进一步得到证实。NRB驱动的铁氮循环影响腐蚀层的稳定。
(3)为了进一步考察非稳定态的地下水管网腐蚀特性,研究了氯胺消毒的铸铁管网腐蚀产物与管垢微生物特性。氯胺的降解导致水体中氨的增加,腐蚀初期硝化作用明显,硝酸盐还原受抑制;随着反硝化菌比例的增加,反硝化占主导地位。α-FeOOH为其主要腐蚀产物,与氯消毒管网相比,氯胺管网中腐蚀产物较致密。分子生物学表征结果说明氯胺增加了水体中 NRB和IOB相对含量,说明 NRB驱动的硝酸盐还原的二价铁氧化促进致密腐蚀层形成。
Other Abstract    Water shortage has been  a serious problem in many cities over  the world while
water source switches applied to  alleviate the pressure of the water supply.  Unstable
corrosion  scales  might   trigger  “red  water”  issues   when  water  quality  entering
distribution systems changed significantly.  The groundwater and surface water from a  northern   city  drinking  water   treatment  plants  were   used  in  this   study.  The experimental  pipe distribution  systems and  biofilm  annular reactors  (BARs)  were used   to  simulate   the   DWDSs   combined   with  the   methods   of   XRD,  SEM,
PCR-DGGE and pyrosequencing. The purpose of this research was to investigate the corrosion processes and effects of  water quality on corrosion stability in distribution systems with different water sources. The main conclusions were as follows.
(1) Aged cast  iron pipes from  both affected and  unaffected areas were  used to establish   experimental    drinking    water   distribution    systems   under    different disinfection  conditions. In  pipe  samples  from  the unaffected  area,  the  dense and thick corrosion layer  included predominantly -FeOOH, Fe3O4,  and γ-FeOOH, and iron-reducing bacteria  (IRB)  were predominant  with fewer  iron-oxidizing bacteria (IOB)  such   as  Gallionella   sp.  being   observed.  The  composition   of  corrosion products  did not  exhibit  large variation  over  time  although their  crystallinity  did exhibit a  slight decrease  throughout the  duration of  the experiment. In  contrast, in the pipe samples from  the affected area, the corrosion  layer was thinner and loosely attached  with  -FeOOH  being  the  main  compound  present.   Compared  to  pipe samples from  the unaffected area,  less γ-FeOOH  and Fe3O4 were  present and  IOB such  as  Gallionella  sp.   and  Sediminibacterium  sp.  were  the  dominant   bacteria observed.  With increasing  time,  the corrosion  layers  became  significantly thicker and IRB  appeared  in pipe  samples from  the affected  area which  had  been treated with  chlorine  and  chloramine   as  disinfectants.  These  results   indicated  that  the synergistic interaction of  IRB/IOB with the  dense corrosion layer inhibited  the iron release from a cast iron pipe following changes in water quality.
(2) The composition of biofilm bacterial communities  and iron corrosion scales were  studied in  two drinking  water distribution  systems  transporting groundwater (DWDS-GW) and surface  water (DWDS-SW),as well  as biofilm annular  reactors (BARs).  The  results showed  that  a  loose corrosion  layer  was  formed  containing reddish filaments of α-FeOOH with a BET surface area  of 85.5 m2g-1 in DWDS-GW,while  in DWDS-SW,  a  dense  corrosion  layer was  formed,  including  crystallized particles of α-FeOOH, γ-FeOOH, Fe3O4 and CaCO3 with a  BET surface area of 18.8 m2g-1. Based on the MPN enumerations and qPCR of denitrifying functional bacteria,the formation of corrosion  products was mainly affected by nitrate-dependent  Fe(II)oxidation of NRB-Fe and Fe(II) oxidation of  IOB Sediminibacterium in the DWDSs transporting GW with nitrate concentration from  5 to 7.9 mg N L-1,  but reduction of Fe(III) and oxidation of Fe(II) occurred from the anaerobic respiration of NRB-Fe  in the DWDSs  transporting SW  with lower  nitrate concentration (0.9~2.2  mg N  L-1).These  results   were  consistent   with  the   research  in  BARs.   It  was   found  that nitrate-reducing bacteria  in biofilms  that are  associated with  iron cycling  played a large role in the stability corrosion layers.
(3)  The  effect of  chloramine  disinfection  on  bacterial  communities  and  the corrosion of cast  iron pipes was  also studied in  drinking water distribution  systems (DWDSs) transporting  groundwater. α-FeOOH  was the main  corrosion product  for both  systems. Most  of  the  NO3- -N in  the  raw  water was  biologically  denitrified through chlorine DWDSs  in the experimental period,  whereas the same phenomena occurred only  when denitrifying  bacteria were  increased in  the effluent  due to  the role  of  autotrophic microbial  nitrification  in  chloramine  DWDSs.  Furthermore,nitrate-dependent  Fe(II) oxidation  occurred  to  a  greater extent,  leading  to  denser corrosion scales  in DWDSs  with chloramine compared  with those disinfected  with chlorine.
(4) The effects of groundwater and surface water under different Larson  indices on cast  iron corrosion  were studied.  The results show  that the  Larson index  is not enough to fully express corrosion difference between groundwater and surface water while nitrate concentration  and microbial components under  different water sources may play a large role on the corrosion stability and network features.
Document Type学位论文
Recommended Citation
GB/T 7714
李肖肖. 水源水质对铸铁管网腐蚀稳定性的影响[D]. 北京. 中国科学院研究生院,2015.
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