【作者】 王洁；

【导师】 胡振；

【作者基本信息】 山东大学 ， 资源与环境（专业学位）， 2023， 硕士

【摘要】 水资源是社会发展重要的基础性自然资源和战略性经济资源。随着我国经济的快速增长,城市化、现代化进程与水资源短缺、水资源污染之间的矛盾日益突出。城市污水的再生回用是缓解水资源短缺、保护生态环境的重要途径。人工湿地是污水再生回用的核心净化设施之一,具有基建投资省、运行费用低、景观优美等优点。近年来,为解决湿地占地面积大与城镇用地稀缺的矛盾,优化人工湿地“空间-性能”配置的深床人工湿地系统得到了广泛关注。然而,随着深度增加,湿地底部微生物数量锐减,碳源不足的现象加剧,导致系统脱氮效果恶化,限制了深床人工湿地的大规模推广应用。本文构建了不同类型的自养反硝化强化型深床人工湿地系统,探究了自养反硝化强化型深床人工湿地纵向维度下的氮转化过程,并运用微生物分子生态学和同位素示踪技术等研究了自养反硝化深床人工湿地系统对氮素的强化去除机制,探究了自养反硝化强化型深床人工湿地对典型抗生素(SMX)的去除效果,并借助降解产物毒性预测和生态毒性实验等手段对深床人工湿地的生态效应进行评价,通过量化环境因素、营养物质和氧化还原指标对深床人工湿地抗生素去除的影响,揭示了自养反硝化深床人工湿地系统对SMX的去除机理,为深床人工湿地在城市污水回用的推广应用提供了理论依据和技术支撑。主要结论如下:(1)自养反硝化方式的引入将深床人工湿地对氮的去除效果提升了 16.57-40.95%。TN的去除效果从高到低依次是Fe-CW>E-CW>P-CW>Mn-CW>C-CW。通过对深床人工湿地沿程氮形态分析发现,上层石英砂层中异养反硝化过程占据优势,此时E-CW、P-CW、Mn-CW 和 Fe-CW 对 NO3--N 的去除率分别为 83.87%、76.20%、66.58%和 43.28%。中间石英砂层中,各组均出现了 NO3--N的积累。虽然底层中微生物的丰富度明显降低,但是功能菌在门水和属水平均有明显的富集,证明了氮素通过底层微生物作用实现了进一步去除。(2)自养反硝化方式的引入对降低N2O的释放通量有显著的促进作用。15N同位素示踪结果表明,深床人工湿地中N2O的排放主要发生于NO3--N的还原过程。Fe-CW中Fe/Fe2+作为电子供体参与自养反硝化的减少了 N2O排放(39.58%)。Mn-CW、P-CW和E-CW中NO3--N对N2O产生的贡献率差异主要由于基质微环境的ORP不同,更低的ORP可以形成更强的还原环境,利于N2O减排。(3)自养反硝化强化型深床人工湿地系统对SMX的去除效能明显提升。电化学方式的引入(Fe-CW和E-CW),对SMX的去除率超过70%,同时,Fe-CW出水和基质层中所有ARGs(sul1、sul2、intl1)的相对丰度显著低于其他系统,表现出最小耐药细菌和耐药基因的选择压力。SMX去除相关性分析发现,不同深床人工湿地系统中SMX的去除机理明显不同。Fe-CW和P-CW中SMX的去除与营养物质指标(TN、TP)呈现出显著相关性,而在E-CW中SMX的去除则与环境因素(ORP)呈现显著相关性。(4)微生物降解是深床人工湿地中SMX的主要去除机制(9.90-34.71%),其次是基质吸附(9.12-22.23%),植物吸收占比较小(4.27-10.10%)。Fe-CW和E-CW显著提升了深床人工湿地系统中物种的丰富度。在门水平上,变形菌门、放线菌门和厚壁菌门相对丰度增加,在属水平上富集了对抗生素具有强降解能力假单胞菌属。除此之外,Fe-CW和E-CW的生态毒性和遗传毒性风险也显著低于其他实验组,成为深床人工湿地中实现典型抗生素去除并保证其生态效应的最优选择。更多还原

【Abstract】 Water resource is an important basic natural resource and strategic economic resource for social development.Since the reform and opening up,with the rapid growth of China’s economy,the contradiction between the process of urbanization and modernization and the shortage and pollution of water resources has become increasingly prominent.Urban sewage is the second source of water in water-scarce cities,and the recycling of sewage is an important way to alleviate the shortage of water resources,protect the ecological environment,and realize the recycling of sewage,which plays an important role in water resources conservation and water pollution control.As a kind of sewage ecological purification technology with low infrastructure investment,low operating cost and beautiful landscape,constructed wetland has been paid more and more attention to its interception and degradation of nitrogen,antibiotics and other pollutants,and improve the natural purification function of urban water.In recent years,the deep bed constructed wetlands that optimize the "space-performance" configuration of constructed wetland has attracted extensive attention.However,with the increase of the depth,the number of microorganisms at the bottom of the constructed wetland decreases sharply,and the shortage of carbon sources has intensified,resulting in the nitrogen removal effect of the system does not improve but shows a downward trend,which limits the further research of the deep bed constructed wetland.In this paper,different types of autotrophic denitrification enhanced deep bed constructed wetlands were constructed to explore the nitrogen transformation process in the vertical dimension of autotrophic denitrification enhanced deep bed constructed wetland,and the enhanced nitrogen removal mechanism of autotrophic denitrification deep bed constructed wetland was studied by using microbial molecular ecology and isotope tracing technology.The removal effect of typical antibiotics(SMX)in deep bed constructed wetland enhanced by autotrophic denitrification was explored,and the ecological effect of deep bed constructed wetland was evaluated by means of degradation product toxicity prediction and eco-toxicity experiment.The influence of environmental factors,nutrients and REDOX indexes on antibiotic removal in deep bed constructed wetland was quantified.The removal mechanism of SMX by autotrophic denitrification deep bed constructed wetland was revealed,which provides theoretical basis and technical support for the promotion and application of deep bed constructed wetland in urban sewage reuse.The main conclusions are as follows:(1)The introduction of autotrophic denitrification improved the nitrogen removal efficiency of deep bed constructed wetland by 16.57%to 40.95%.The removal effect of TN from high to low is Fe-CW>E-CW>P-CW>Mn-CW>C-CW;C minus CW.Through the analysis of nitrogen morphology along the deep bed constructed wetland,it was found that the heterotrophic denitrification process was dominant in the upper quartz sand layer,and the removal rates of NO3--N by E-CW,P-CW,Mn-CW and Fe-CW were 83.87%,76.20%,66.58%and 43.28%,respectively.In the middle layer of quartz sand,the accumulation of NO3--N appeared in all systems.Although the underlying functional substrate layer reduced microbial richness,functional bacteria were significantly enriched at both phyla and genus levels,proving that further nitrogen removal was achieved through the underlying functional substrate layer.(2)The introduction of autotrophic denitrification can significantly promote the reduction of N2O release flux.The results of 15N isotope tracing showed that the emission of N2O in the deep bed constructed wetland mainly occurred in the process of NO3--N reduction.Fe/Fe2+as electron donor in Fe-CW reduced N2O emission by 39.58%.The difference in the contribution rate of NO3--N to N2O production in Mn-CW,P-CW and E-CW is mainly due to the different ORP of the substrate microenvironment.(3)The autotrophic denitrification enhanced deep bed constructed wetland significantly improved the removal efficiency of SMX.Among them,the removal rate of SMX by the introduction of electrochemical methods(Fe-CW and E-CW)was more than 70%.Meanwhile,the relative abundance of all ARGs(sul1,sul2,intl1)in the effluent and substrate layer of Fe-CW was significantly lower than that of other systems,showing the selection pressure of least resistant bacteria and resistance genes compared with other systems.The correlation analysis of SMX removal in each system showed that the SMX removal mechanism was obviously different in different deep bed constructed wetlands.SMX removal in Fe-CW and P-CW showed a significant correlation with nutrient indices(TN,TP),while SMX removal in E-CW showed a significant correlation with environmental factors(ORP).(4)Microbial degradation was the main removal mechanism of SMX in all deep bed constructed wetlands(9.90-34.71%),followed by substrate adsorption(9.12-22.23%)and plant absorption(4.27-10.10%).Fe-CW and E-CW significantly improved the species richness of the deep bed constructed wetland system.At the phylum level,the relative abundance of Proteobacteria,Actinobacteria and Firmicutes increased,and at the genus level,Pseudomonas,which has a strong ability to degrade antibiotics,was enriched.In addition,the eco-toxicity and genotoxicity risks of Fe-CW and E-CW were also significantly lower than those of other experimental systems,which made Fe-CW and E-CW the optimal choices for the removal of typical antibiotics and ensuring their ecological effects in deep bed constructed wetlands.更多还原