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臭氧组合工艺对饮用水和污水中抗生素和抗药基因的去除研究
Alternative TitleElimination of antibiotics and antibiotic resistance genes in water and wastewater by ozone based combination processes
李钢
Subtype博士
Thesis Advisor强志民
2018-12
Degree Grantor中国科学院生态环境研究中心
Place of Conferral北京
Degree Name工学博士
Degree Discipline环境工程
Abstract

      作为环境中一类重要的污染物,抗生素所带来的健康风险和生态环境问题引起了各国学者和公众的广泛关注。同时,抗生素诱导细菌抗性不断增强以及抗生素抗性基因(Antibiotic resistance genes, ARGs)大量增殖,ARGs能够在不同环境介质中传播和扩散,增加了病原菌获得抗生素抗性的机会,严重威胁人类健康。近年来,臭氧-生物活性炭(Ozone-biological activated carbon, O3-BAC)工艺被越来越多的应用到饮用水和污水处理中。基于此,本文研究了 O3-BAC工艺对饮用水和城市污水中多种抗生素及 ARGs的去除效果。此外,污泥是  ARGs的“汇”,ARGs的存在对污泥的处理与处置带来了较大的环境风险,本文也对污泥O3氧化过程中 ARGs的削减进行了研究,提出了优化组合工艺。主要结论如下:
      (1)以上海给水技术验证基地滤后水为研究水体,开展了 O3-BAC工艺中试研究,考察了该工艺对磺胺类抗生素(  Sulfonamides,  SAs)及磺胺类抗药菌(Sulfonamide resistant bacteria, SRB)的削减效果。结果表明,O3能够有效地去除水中 SAs,在 O3投加量为  2.5 mg L‒1时,8种目标  SAs在  O3-BAC工艺中的去除率超过了 90%。单独 BAC工艺中,较大的空床接触时间(Empty bed contact time,EBCT)能有效促进 SAs的去除,在  EBCT为   20  min时,8种   SAs的去除率为58%–83%。在 O3投加量为  0.5和  2.5 mg L‒1时,单独 O3对异养菌(Heterotrophicplate counts, HPCs)的去除率分别为 0.12和  0.47 logs。然而,经过 O3-BAC工艺后出水中 SRB出现了升高,表明后续消毒(如氯和氯胺)工艺对保障饮用水安全的重要性。同时,O3-BAC工艺能够有效降低氯代消毒副产物—三卤甲烷生成势(Trihalomethanes  formation potential,  THMsFP)和卤乙酸生成势(Haloaceticacids formation  potential, HAAsFP)。此外,对于总有机碳(Total  organic carbon,TOC)、254 nm UV transmittance(UV254)和浊度的去除,该工艺同样很有效。
      (2)以某城市污水处理厂生物处理出水为研究水体,进行了 O3-BAC工艺去除抗生素、抗生素抗药菌(Antibiotic resistant bacteria, ARB)和 ARGs的中试研究。结果显示,生物处理出水中检出多种抗生素:四环素类抗生素(Tetracyclines,TCs)的浓度为 7.46–28.82(氧四环素,Oxytetracycline)和 1.18–24.09 ng L‒1(四环素,Tetracycline);检出浓度较高的 SAs分别为磺胺甲恶唑(Sulfamethoxazole,25.87–104.92 ng L‒1)和磺胺噻唑(Sulfathiazole, 24.58–81.06 ng L‒1);氟喹诺酮类抗生素(Fluoroquinolones, FQs)中浓度最高的是氧氟沙星(Ofloxacin, 160.77–450.83 ng L‒1)。运行初期未启动 O3,活性炭对多种抗生素的去除率在 90%以上,但对 TCs和  FQs去除率较低(20%-30%);随着运行时间的延长,这两类抗生素的去除率接近 100%。单独 BAC对  HPCs的去除率为  0.08–1.50 logs;在 O3剂量为 5–20 mg L‒1,O3-BAC工艺能够实现  0.11–2.0 logs的  HPCs去除。然而,O3-BAC工艺出水中仍然含有一定数量的 HPCs和  ARB。BAC工艺对  ARB的截留作用较弱,而 O3-BAC整体工艺则能较有效地削减  ARB,在 O3剂量为  20  mg L‒1时,对四环素抗药菌(Tetracycline resistant bacteria, TRB)的灭活率为 1.3 logs。生物处理出水中,不同种类的 ARGs绝对含量差异较大,磺胺类抗性基因(Sulfonamide resistance genes, SRGs)、四环素类抗性基因(Tetracycline resistance genes, TRGs)和氟喹诺酮类抗性基因(Fluoroquinolone resistance  genes,  FRGs)的绝对含量较高。O3-BAC工艺对  ARGs和一类整合子(Class  1 integron, intI1)具有一定的削减能力。此外,O3-BAC工艺进出水中微生物群落结构发生了显著变化。
(3)对污泥中 ARGs的研究表明,SRGs和   TRGs被广泛检出,绝对含量分别为 6.45 × 108和3.61 × 107copies g–1dw(污泥干重)。在污泥 O3氧化过程中,O3剂量对污泥中  ARGs的削减具有一定的影响,在 O3剂量为185 mg g–1MLSS(Mixed liquor suspended solids)时,TRGs和  SRGs分别降低了 0.83和  0.52 logs。不同 pH条件影响  ARGs在污泥固、液两相中的分配,pH值为  5.0或  9.0时,污泥固相中 ARGs的绝对含量高于其在中性条件下的绝对含量。ARGs与intI1和二类整合子(Class 2  integron, intI2)均具有较强的相关性(p <  0.05),说明整合子是 ARGs发生迁移的重要载体。为了提升污泥  O3减量工艺中  ARGs的削减效果,考察了多种预处理技术与 O3的组合工艺对污泥中  ARGs的削减。结果表明,Ca(OH)2预处理能够有效地提高污泥  O3氧化对 ARGs的削减,在   Ca(OH)2投加量为 8.36 g L–1时,污泥固相中TRGs和  SRGs分别降低了  2.52和 1.73 logs。微波-双氧水预处理比单独微波预处理对污泥 O3氧化过程中 ARGs的削减更有效。

Other Abstract

      As an important  class of emerging  contaminants, antibiotics have  been received increasing attentions  for their  potential threat  to ecological  environment  and human health.  Meanwhile,  antibiotics  would  enhance  the resistant  level  of  microbes  and promote the proliferation of antibiotic resistance genes (ARGs). ARGs could transport between different environmental media, thus increasing the opportunities for pathogen to  acquire  resistance  and  posing  a severe  threat  on  public  health.  Ozonation  and biological activated carbon  (O3-BAC) process is increasing  applied in drinking water treatment plants (DWTPs) and wastewater  treatment plants (WWTPs) in recent years.
Based on this, the present study investigated the  performance of O3-BAC in removing different kinds of antibiotics and ARGs  from water and wastewater. Moreover, sludge is  an important  “reservoir”  of  ARGs,  the existence  of  ARGs  in sludge  incurs  the environmental risks  during the treatment  and disposal  of sludge, therefore,  O3-based
processes were  selected to investigate  the removal of  ARGs in the  sludge. The main results are as follows:
      (1)   Taking  the  filtered  water  from water  supply  test  base  of Shanghai  as  the water matrix, a field pilot-scale  study was carried out on the removal of  sulfonamides (SAs)  and  sulfonamide  resistant bacterial  (SRB)  by  O3-BAC  process.  The  results indicated that  O3 could effectively  remove SAs from  water and the  removal of eight SAs exceeded 90% at the O3 dose  of 2.5 mg L‒1. In BAC process alone, higher empty bed contact  time (EBCT)  greatly enhanced  the removal  of SAs  and at  EBCT of  20min, the  removal of  eight SAs reached  58%–83%. The  inactivation of heterotrophic plate counts (HPCs) at  the O3 dose of 0.5 and  2.5 mg L‒1 reached 0.12  and 0.47 logs,respectively. However, the amount of SRB increased after the O3-BAC process, which highlights the importance of subsequent disinfection process (such  as chlorination and chloramine  disinfection)   for  ensuring   the  safety  of   drinking  water.   Meanwhile,O3-BAC  process  could  effectively  reduce  chlorinated  by-products:  trihalomethane formation potential (THMsFP)  and haloacetic acid formation  potential (HAAsFP). In addition, the process was also effective for the removal of total organic carbon (TOC),UV254 and turbidity.
      (2)   The  effluent from  biological treatment of  a WWTP  was selected as  the test water,  a  pilot-scale  test  was  carried  out  for  the  removal  of  antibiotics,  antibiotic resistance bacteria  (ARB) and ARGs  by O3-BAC  process. The  results indicated that various  kinds  of  antibiotics  were  detected:   the  concentration  of  tetracycline  was 7.46-28.82 ng L‒1    (Oxytetracycline, OTC) and 1.18-24.09 ng L‒1   (Tetracycline, TCN);
SAs with  higher concentrations were sulfamethoxazole  (SMX, 25.87–104.92 ng  L‒1)and   sulfathiazole    (STZ,   24.58–81.06   ng    L‒1);   the   highest    concentration   of fluoroquinolone  antibiotics  was   ofloxacin  (OFL,  160.77–450.83   ng  L‒1).  At   the beginning  of  the operation,  O3  was  not  added  and  the  removal  of most  kinds  of antibiotics by activated carbon exceeded 90%,  but low removal was achieved for TCs and  FQs  (20%–30%).  As  the  operation  time extended,  the  removal  of  these  two antibiotics was  close to 100%.  The inactivation of HPCs  by BAC process  alone was 0.08–1.50 logs and  at the O3 dose of  5–20 mg L‒1, the inactivation  could reach 0.11–2.00  logs. However,  a  certain amount  of  HPCs  and SRB  was  still  detected in  the effluent of O3-BAC  process. BAC process alone could  not inactivate the ARB,  while the  O3-BAC  process could  achieve  effective  inactivation.  The  inactivation  rate of tetracycline  resistant  bacteria  (TRB)  was  1.3  logs  at  the  O3  dose  of  20  mg  L‒1.Different  kinds  of  ARGs  showed  distinct   distribution  patterns  in  the  effluent  of biological  treatment:  sulfonamide  resistance  genes  (SRGs),  tetracycline  resistance genes (TRGs) and  fluoroquinolone resistance genes (FRGs)  were dominant. O3-BAC process had a certain reduction capacity towards ARGs and class 1 integron  (intI1).  In addition, the microbial  community structure changed significantly  in the influent and effluent of O3-BAC process.
       (3)   The  investigation  on ARGs  of sludge  revealed  that SRGs  and  TRGs were widely detected  in sludge, the  absolute gene  copies were  6.45 × 108   and  3.61 × 107 copies  g–1dw  (dry  weight),  respectively.  O3  dose  had  a  certain  influence  on  the quantity  of ARGs  in  sludge  ozonation. At  the  O3 dose  of  185  mg g-1     MLSS, the quantities  of  TRGs  and  SRGs  were reduced  by  0.83  and  0.52  logs, respectively.Different pH values affected the distribution of the  liquid phase and solid phase of the sludge. The  quantity of  ARGs in  solid phase of  sludge was  higher at  pH 5.0  or 9.0 than that under neutral condition. The target ARGs were strongly correlated with intI1 and class  2 integron (intI2)  (p < 0.05).  The integrons  were important vectors  for the migration of ARGs.  With the aim of  enhancing the reduction of ARGs  during sludge ozonation,  the present  study  combined different  pretreatment  processes  with  O3 to investigate  the  reduction   of  ARGs.  The  results   indicated  that  pretreatment  with Ca(OH)2  could effectively  promote the  reduction of  ARGs  in the  sludge ozonation
and  the   quantities  of   TRGs  and   SRGs  were   reduced  by   2.52  and   1.73  logs,respectively, at the  Ca(OH)2 dose of 8.36 g  L–1  . Microwave  combined with hydrogen peroxide  pretreatment  showed  higher  reduction   capacity  than  microwave  process alone on ARGs reduction during sludge ozonation.
 

Pages137
Language中文
Document Type学位论文
Identifierhttp://ir.rcees.ac.cn/handle/311016/42230
Collection环境水质学国家重点实验室
Recommended Citation
GB/T 7714
李钢. 臭氧组合工艺对饮用水和污水中抗生素和抗药基因的去除研究[D]. 北京. 中国科学院生态环境研究中心,2018.
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