【作者】 赵辉；

【导师】 文刚；

【作者基本信息】 西安建筑科技大学 ， 建筑与土木工程， 2021， 硕士

【摘要】 饮用水中的真菌具有一定的致病性、致敏性和致毒性,对人体健康和环境产生了负面影响,在供水系统中均检出不同浓度的曲霉,因此其已成为人们研究的热点。目前已有多种控制水中真菌污染的消毒方法,其中紫外（UV）和紫外氯体系（UV/Cl₂）已有广泛研究,而紫外/氯胺体系（UV/NH₂Cl）的研究相对较少。UV/NH₂Cl作为一种新兴的高级氧化工艺（AOPs）可以产生活性自由基,从而实现对于有机污染物的降解及部分致病细菌的消毒,但目前尚未见其对于真菌污染控制的研究。此外,真菌可以通过光复活的形式修复UV引起的损伤。本文以饮用水中常见的三种曲霉（黑曲霉Aspergillus niger、黄曲霉Aspergillus flavus、烟曲霉Aspergillus fumigatus）为研究对象,通过UV/NH₂Cl体系的联合和顺序灭活进行了其灭活效能及机制的研究并就控制曲霉光复活的效果进行了研究。此外,与UV和UV/Cl₂两种体系进行了相应对比,评估UV/NH₂Cl体系的适用性。得到以下结论:（1）紫外剂量达到160 m J/cm²时,单独UV（254 nm）可灭活三种曲霉3.50-log₁₀以上,曲霉的紫外抗性为:黄曲霉>黑曲霉>烟曲霉。UV/NH₂Cl（3.0 mg/L）可比单独UV（254 nm）更有效的灭活三种曲霉,其灭活值可达5.10-log₁₀以上。UV/Cl₂（3.0mg/L）对三种曲霉的灭活值可达3.50-log₁₀以上,弱于UV/NH₂Cl（3.0 mg/L）的灭活结果。两种联合灭活方式对于三种曲霉的灭活均无协同作用。NH₂Cl-UV在三种顺序灭活方式（UV-NH₂Cl、NH₂Cl-UV、UV/NH₂Cl-UV）中表现出最好的灭活效果,灭活值可达4.20-log₁₀以上,高于UV/Cl₂体系的顺序灭活方式（UV-Cl₂、Cl₂-UV、UV/Cl₂-UV）的灭活结果。三种曲霉的灭活过程符合一级动力学Chick-watson模型。三种曲霉的灭活结果存在差异的原因主要是由于孢子尺寸、孢子色素以及孢子疏水性的差异。（2）单独UV（254 nm）灭活2-log₁₀后的三种曲霉在UVA（365 nm）照射480min后出现不同程度的光复活,且光复活趋势呈现一致性,最大存活率为:黑曲霉>黄曲霉>烟曲霉,三种曲霉的光复活率表现出差异的主要原因是光解酶的数量和活性不同。UV/NH₂Cl和UV/Cl₂可比单独UV（254 nm）更有效的控制三种曲霉的光复活,最大可分别降低光复活率至1%以下和2%以下,NH₂Cl和Cl₂的添加可以不同程度的降低光复活后的最大存活率S_m和光复活速率常数k₁。黑曲霉和烟曲霉经过480 min的光复活之后,UV/NH₂Cl（2.0 mg/L）对两者的光复活控制效率分别为81.50%和81.62%,高于UV/Cl₂（2.0 mg/L）的47.20%和81.38%。UV/Cl₂（2.0 mg/L）对于黄曲霉的光复活控制效率为40.42%,高于UV/NH₂Cl（2.0 mg/L）的27.39%。（3）单独UV（254 nm）会引起烟曲霉的膜受损孢子数增加75.80%,胞内高ROS水平增加24.25%,黑曲霉和黄曲霉的膜受损孢子数增加较少,黄曲霉的胞内高ROS水平增加了41.90%。相比单独UV（254 nm）,UV/NH₂Cl（2.0 mg/L）和UV/Cl₂（2.0mg/L）可以明显提高三种曲霉的膜受损孢子数和胞内高ROS水平。单独UV（254nm）灭活后,烟曲霉的SEM图像出现了明显凹陷和褶皱。而UV/NH₂Cl（2.0 mg/L）和UV/Cl₂（2.0 mg/L）灭活后,三种曲霉都出现了变形和损伤,烟曲霉损伤最严重,黄曲霉和黑曲霉对不同灭活方式表现出的灭活抗性不同,损伤存在差异。UV/NH₂Cl与UV/Cl₂灭活三种曲霉的成本优劣与灭活值相关。更多还原

【Abstract】 Fungi have certain pathogenicity,sensitization and toxicity,and have a negative impact on human health and the environment in drinking water.The Aspergillus of different concentrations were detected in the water supply system,so it has become a research hotspot.At present,there are many disinfection methods for controlling fungal pollution in water.Among them,Ultraviolet（UV）and Ultraviolet chlorine system（UV/Cl₂）have been extensively studied,while the research on Ultraviolet/monochloramine system（UV/NH₂Cl）is relatively small.As a new emerging advanced oxidation process（AOPs）,UV/NH₂Cl can generate active free radicals,thereby achieving the degradation of organic pollutants and the disinfection of some pathogenic bacteria.However,there is no research on fungal pollution control.In addition,the damage of the fungi caused by UV can be repaired in the form of photoreactivation.In this paper,three common Aspergillus species（Aspergillus niger,Aspergillus flavus,Aspergillus fumigatus）were taken as the research objects in drinking water,and the inactivation efficiency and mechanism were studied through the combination of UV/NH₂Cl combination and sequential inactivation.And studied the effect of controlling the photoreactivation of Aspergillus species.In addition,a corresponding comparison was made with the UV and UV/Cl₂ systems to evaluate the applicability of the UV/NH₂Cl system.The conclusions as follows:（1）When the UV dose was 160 m J/cm²,UV alone（254 nm）could inactivate three Aspergillus species above 3.50-log₁₀.The UV resistance of Aspergillus species was:Aspergillus flavus>Aspergillus niger>Aspergillus fumigatus.UV/NH₂Cl（3.0 mg/L）was more effective than UV alone（254 nm）to inactivate three Aspergillus species,and the value of inactivation can reach more than 5.10-log₁₀.The inactivation value of UV/Cl₂（3.0 mg/L）for the three Aspergillus species could reach more than 3.50-log10,which was lower than the inactivation result of UV/NH₂Cl（3.0 mg/L）.The two combined inactivation methods have no synergistic effect on the inactivation of the three Aspergillus species.NH₂Cl-UV owned the best inactivation effect among the three sequential inactivation methods（UV-NH₂Cl,NH₂Cl-UV,UV/NH₂Cl-UV）,and the inactivation value could reach more than 4.20-log₁₀,which was higher than the result of the sequential inactivation method（UV-Cl₂,Cl₂-UV,UV/Cl₂-UV）.The inactivation process of the three Aspergillus species conformed to the first-order kinetic Chick-watson model.The reason for the differences in the inactivation of the three Aspergillus species was mainly due to the differences in size,pigment,and hydrophobicity of the spores.（2）The three Aspergillus species after 2-log₁₀ inactivation by UV（254 nm）alone showed different degrees of photoreactivation after UVA（365 nm）irradiation for 480 min,and the photoreactivation trend was consistent.The maximum survival rate was:Aspergillus niger>Aspergillus flavus>Aspergillus fumigatus,the difference in the number and activity of photolyase was the main reason for the difference in the photoreactivation rate of the three Aspergillus species.UV/NH₂Cl and UV/Cl₂ could control the photoreactivation of the three Aspergillus species more effectively than UV alone（254 nm）,and could reduce the photoreactivation rate to less than 1%and less than 2%,respectively.The NH₂Cl and Cl₂ could be added to different degrees to decrease the maximum survival rate S_m after photoreactivation and the photoreactivation rate constant k₁.After Aspergillus niger and Aspergillus fumigatus have undergone 480 min of photoreactivation,the control efficiency of UV/NH₂Cl（2.0 mg/L）was 81.50%and 81.62%,respectively,which was higher than the result of UV/Cl₂（2.0 mg/L）that it was 47.20%and 81.38%.UV/Cl₂（2.0 mg/L）has a photoreactivation control efficiency of 40.42%for Aspergillus flavus,which was higher than the result of 27.39%of UV/NH₂Cl（2.0 mg/L）.（3）UV alone（254 nm）would cause the number of damaged spores of Aspergillus fumigatus to increase by 75.80%,the high intracellular ROS level increases by 24.25%,and the number of damaged spores of Aspergillus niger and Aspergillus flavus increases less.The high intracellular ROS levels of Aspergillus flavus increased by 41.90%.Compared with UV alone（254 nm）,UV/NH₂Cl（2.0 mg/L）and UV/Cl₂（2.0 mg/L）could significantly increase the number of membrane-damaged spores and high intracellular ROS levels of the three Aspergillus species.After UV（254 nm）alone inactivation,the SEM image of Aspergillus fumigatus showed obvious depressions and wrinkles.After UV/NH₂Cl（2.0 mg/L）and UV/Cl₂（2.0 mg/L）were inactivated,Aspergillus species showed deformation and damage.And Aspergillus fumigatus was the most severely damaged.The inactivation resistance was different,and the damage was different.The cost of UV/NH₂Cl and UV/Cl₂ inactivation of the three Aspergillus species was related to the inactivation value.更多还原