紫外线和氯组合方式对大肠杆菌灭活效果的影响研究

系统地比较了紫外线和氯不同的组合方式对大肠杆菌的灭活效果.结果表明,紫外线和氯联合顺序消毒在一定程度上提高了消毒效果,但不同的组合方式以及两者不同的剂量对灭活效果都有影响.紫外线和氯先后作用的消毒效果优于紫外线和氯同时消毒.先氯后紫外线消毒时,加较高浓度的氯且短时间接触即可达到较好的消毒效果;先紫外线后氯消毒时,氯剂量越大则灭活率越高,若氯浓度相同而接触时间不同,则灭活效果差别不大.     

超声预处理强化紫外线消毒效果的研究

采用超声预处理强化紫外线消毒效果,并从分子生物学的角度探讨了其强化机理.结果表明,无论是单独紫外辐照还是超声预处理/紫外辐照,紫外辐照剂量与大肠杆菌灭活率之间均具有良好的线性关系;进行超声灭活时,超声功率、作用时间及菌悬液体积对灭活率均无显著意义(P>0.05),按影响大小排序为:菌悬液体积>超声功率>作用时间;当单独超声处理200 mL大肠杆菌悬液时,超声功率为200 W、作用时间为20 S条件下的灭活率最高(0.22-1g),该条件下继续进行紫外辐照,灭活率最高达到2.75-1g,1 h光复活后灭活率仍高达1.72-1g,超声/紫外协同作用的灭活率大于二者单独作用的灭活率之和,表明该条件下超声预处理起到了强化紫外线消毒的作用;超声处理只能改变细胞的结构,不能破坏其DNA;酶敏感位点数量与大肠杆菌的灭活率具有较强的相关性,相关系数约为0.88.     

紫外线及联合工艺对水中微生物的灭活效果

通过使用微生物对数灭活率(MIC)和灭活率常数(k)两项指标,考察了紫外线消毒对不同种类微生物的灭活效果,建立了微生物对数灭活率达到1 lg～ 4lg时所需紫外剂量表,分析了紫外线对耐氯性微生物的灭活特点.由于单独采用紫外线消毒技术对水中部分病毒、噬菌体和芽孢型细菌的灭活效率较低,故又考察了UV/C12、UV/H202以及UV/03等紫外线相关工艺对耐紫外线微生物的灭活效果.对紫外线消毒目前存在的问题以及今后的发展方向作了总结与展望.     

紫外线消毒对光复活时大肠杆菌活性的影响

以大肠杆菌为研究对象，考察了紫外线消毒对大肠杆菌的灭活效果及紫外线消毒后大肠杆菌在可见光下发生光复活的情况，同时考察了紫外线消毒和光复活过程中大肠杆菌电子传递体系（ETS）活性的变化。结果表明，大肠杆菌的灭活率随着紫外线剂量的增加而提高，在相同剂量下高强度的紫外线对大肠杆菌的灭活效果好于低强度的紫外线。经紫外线灭活后的大肠杆菌在可见光下会发生光复活，紫外线剂量对大肠杆菌的光复活有一定影响，高剂量下大肠杆菌发生光复活的能力比低剂量下的差；相同剂量下，较高强度的紫外线有利于控制大肠杆菌的光复活。对大肠杆菌ETS活性的研究表明，随着紫外线强度和剂量的增加，大肠杆菌的活性不断降低；紫外线消毒后的大肠杆菌经可见光照射后发生光复活时，其活性有所增加，在较高的紫外线剂量和强度下大肠杆菌的活性增加较少，而在较低剂量和强度下大肠杆菌的活性恢复能力较强。     

紫外线消毒应对小规模供水单元突发性微生物污染研究及工程实例

结合B市M单位自备井微生物污染事件及应对过程,以小规模供水单元突发性微生物污染为背景,将紫外线消毒作为应对手段,考察了紫外强度、紫外线穿透率对紫外线消毒效果的影响,并研究了大肠杆菌可见光复活.结果表明:较大剂量时,紫外强度对消毒效果的影响会减弱甚至不产生影响;在相同紫外强度条件下,紫外线穿透率对紫外线消毒效果的影响显著...     

黑暗培养环境下紫外线对压载水中海藻的灭活效果

按照《国际船舶压载水及沉积物控制和管理公约》对岸基测试试验的要求,采用准平行光束仪对8种海藻进行紫外线辐射后黑暗环境培养5 d,研究紫外线对它们的灭活效果。结果表明,紫外线对三角褐指藻、中肋骨条藻、盐生杜氏藻和赤潮异弯藻具有一定的灭活效果,灭活率随着紫外线剂量的增加而提高,在剂量为400 mJ/cm2时灭活率分别为48.5%、86.8%、98.2%和100%;小剂量的紫外线辐射会刺激青岛大扁藻的生长,当剂量200 mJ/cm2时藻细胞数量开始缓慢减少,在剂量为400 mJ/cm2时灭活率为15.9%;小剂量的紫外线辐射对小新月菱形藻和塔胞藻具有一定的灭活效果,在剂量300 mJ/cm2时灭活效果开始降低,在剂量为400 mJ/cm2时灭活率分别为42.2%和18.1%;紫外线剂量≤400 mJ/cm2时对利玛原甲藻没有灭活效果。总体来看,紫外线对海藻的灭活效果较差。藻细胞个体大小不是影响紫外线灭活效果的因素,藻的种类、藻细胞壁的有无及其成分的不同可能是造成灭活效果不同的原因。     

城镇污水处理工艺对紫外线消毒RED的影响

使用准平行紫外光束仪测定了重庆市3个采用不同处理工艺的城镇污水处理厂终沉池出水中粪大肠菌群(FC)的紫外线响应曲线,考察了不同处理工艺对紫外线消毒等效生物验证剂量(RED)的影响.结果表明,在15mJ/CM2的紫外线辐照剂量下,3个污水处理厂终沉池出水中的FC未发生光复活和暗复活现象;运用虚拟变量回归分析法对3个水样的试验数据进行统计分析,发现3个水样属于同一个样本空间,表明不同的二级污水处理工艺对紫外线消毒效果没有显著影响;基于数据合并处理的结果,建议新建的城镇二级污水处理厂的紫外线消毒反应器的进水FC浓度设计值取5.0×106MPN/L,以对应1.0×104和1.0×103MPN/L的两个排放标准,REDmsz分别为25和36mJ/cm2.     

紫外线对自来水中微生物的灭活作用

选取大肠杆菌和枯草芽孢杆菌分别代表自来水中易被灭活和不易被灭活的微生物,研究了紫外线的灭菌效果。结果表明:紫外消毒对大肠杆菌具有良好的灭活作用,当紫外剂量为10 mJ/cm2时,可以达到4.66个对数级的灭活效果;在相同的紫外剂量下,紫外强度对灭活效果也有一定的影响,在紫外强度较高时会取得较好的灭活效果;原水浊度对紫外灭活大肠杆菌有一定的影响,当浊度>4 NTU时会明显降低紫外线的灭菌效果,浊度物质的存在降低了水的透光率,从而使灭活效果降低。氯对枯草芽孢杆菌的灭活效果很差,在CT值为300(mg/L).m in时的灭活率也仅为0.53个对数级,紫外线对枯草芽孢杆菌灭活效果要明显高于氯,紫外剂量为40 mJ/cm2时对枯草芽孢杆菌的灭活率可达3.3个对数级。     

紫外线处理排泥水的试验研究

采用紫外线处理水厂排泥水并进行了经济分析。结果表明,紫外处理技术对排泥水有很好的杀菌灭藻效果,并能避免氯消毒带来的消毒副产物问题;静态试验下,灭活水中剑水蚤需要较大的紫外辐射剂量,且照射时间较长;浊度会影响紫外透光率,应尽量降低原水浊度,以保证紫外对生物的灭活效果。     

浅析紫外线消毒对自来水中藻类的去除效果

藻类在清水池、供水管网中繁殖,死亡会在水中散发土臭素、产生藻毒素,藻类与氯反应生成消毒副产物,影响供水安全。G水厂在炭砂滤池和清水池间采用紫外处理工艺。通过分析比较炭池、紫外出水中藻类的数量,紫外线消毒对藻类有较好的去除效果。经检测分析,炭池出水藻类总数与紫外出水藻类总数相比,去除率平均可达到58.85%。且紫外对硅藻门、绿藻门、蓝藻门等不同藻种均有一定的去除效果。紫外线消毒可以对炭砂滤池出水中的部分藻类进行灭活,进一步保证出厂水水质安全。     

医院污水的紫外线消毒研究

对医院污水采用紫外线消毒所需的剂量进行了研究,结果表明:当紫外线剂量为 15mJ/cm2 时,对粪大肠菌的杀灭率可达 99. 999%;未经处理的医院污水,直接采用紫外线消毒的效果不稳定,而经二级处理后的医院污水采用紫外线消毒时可确保出水粪大肠菌稳定在 500个 /L的一级排放标准内。     

Investigation of microbial inactivation efficiency of a UV disinfection system employing an excimer lamp

An ultraviolet (UV) disinfection reactor based on excimer lamp technology was designed by integration of the results of numerical simulations based on computational fluid dynamics and a fluence rate (E') distribution model for cylindrical excimer lamps. The E' distribution model was developed based on a point source approach that accounts for absorption, dissipation, reflection, and refraction within the reactor system. A prototype reactor was constructed with a xenon-bromide excimer lamp and an internal spiral baffle. Experiments were conducted on the reactor to test its effectiveness for disinfection of drinking water in situations where the use of mercury-based UV sources is restricted or undesirable; a similar design approach could be used to develop an excimer UV reactor for disinfection of other fluid media, including wastewater or air.     

再生水紫外-氯组合消毒与单一氯消毒比较分析

利用准平行光束仪对再生水进行了紫外灭活大肠杆茵试验,并考察了紫外-氯组合消毒与单一氯消毒的消毒效果.结果表明,与单一氯消毒相比,紫外-氯组合消毒可有效降低氯的投加量.在组合消毒试验条件下,大肠杆菌完全灭活,紫外剂量从3mJ/cm2提高到5mJ/cm2,加氯量可降低1mg/L;灭活率相同条件下,紫外剂量与加氯量的关系符合...     

Impact of water—Agitation conditions on the dynamics of disinfection of UV radiation and ozone in direct-flow and closed reactors

We have discussed some features of the process of disinfection of water by UV radiation and ozone that substantially affect the final result. In an experimental way we investigated the relationship between the degree of water disinfection and the rate of its stirring. It has been shown that fast bulk stirring leads to opposite results for closed and direct-flow conditions and that for the last condition this is unacceptable. We have conducted design modeling of disinfection processes and comparison of design and experimental data. For treating water with UV radiation tube lamps, we have proposed a “two-dimensional” model of stirring which demonstrated maximum effective use of their lighting capabilities in the reactor’s direct-flow mode.     

Application of GaN-based ultraviolet-C light emitting diodes--UV LEDs--for water disinfection

GaN-based ultraviolet-C (UV-C) light emitting diodes (LEDs) are of great interest for water disinfection. They offer significant advantages compared to conventional mercury lamps due to their compact form factor, low power requirements, high efficiency, non-toxicity, and overall robustness. However, despite the significant progress in the performance of semiconductor based UV LEDs that has been achieved in recent years, these devices still suffer from low emission power and relatively short lifetimes. Even the best UV LEDs exhibit external quantum efficiencies of only 1-2%.The objective of this study was to investigate the suitability of GaN-based UV LEDs for water disinfection. The investigation included the evaluation of the performance characteristics of UV LEDs at different operating conditions as well as the design of a UV LED module in view of the requirements for water treatment applications. Bioanalytical testing was conducted using Bacillus subtilis spores as test organism and UV LED modules with emission wavelengths of 269 nm and 282 nm.The results demonstrate the functionality of the developed UV LED disinfection modules. GaN-based UV LEDs effectively inactivated B. subtilis spores during static and flow-through tests applying varying water qualities. The 269 nm LEDs reached a higher level of inactivation than the 282 nm LEDs for the same applied fluence. The lower inactivation achieved by the 282 nm LEDs was compensated by their higher photon flux. First flow-through tests indicate a linear correlation between inactivation and fluence, demonstrating a well designed flow-through reactor. With improved light output and reduced costs, GaN-based UV LEDs can provide a promising alternative for decentralised and mobile water disinfection systems.     

三种饮用水消毒副产物形成模型对比研究

选取反应时间(t)、水温(T)、pH、总有碳(TOC)、特别紫外吸光度(UV254)、溴离子浓度(Br-)及反应的氯剂量(Cl2)等相关的水质参数,构建了三卤甲烷及卤乙酸两大类消毒副产物的多元线性回归、非线性回归及神经网络预测模型。结果表明,消毒副产物的多元线性回归模型能逐步筛选回归因子,得出影响消毒副产物形成的主要因素及影响程度,各消毒副产物的多元线性回归方程的线性非常显著(p≤0.05);消毒副产物的非线性回归模型能分析预测各种对消毒副产物的影响不呈线性关系的因素;各消毒副产物神经网络预测的判定参数均大于0.83,表明采用神经网络预测消毒副产物的形成可以获得较精确的预测值。     

The influence of oxidation reduction potential and water treatment processes on quartz lamp sleeve fouling in ultraviolet disinfection reactors

Ultraviolet (UV) disinfection systems are incorporated into drinking water production facilities because of their broad-spectrum antimicrobial capabilities, and the minimal disinfection by-product formation that generally accompanies their use. Selection of an optimal location for a UV system within a drinking water treatment facility depends on many factors; a potentially important consideration is the effect of system location on operation and maintenance issues, including the potential for fouling of quartz surfaces. To examine the effect of system location on fouling, experiments were conducted at a groundwater treatment facility, wherein aeration, chlorination, and sand filtration were applied sequentially for treatment. In this facility, access to the water stream was available prior to and following each of the treatment steps. Therefore, it was possible to examine the effects of each of these unit operations on fouling dynamics within a UV system. Results indicated zero-order formation kinetics for the fouling reactions at all locations. Increases in oxidation reduction potential, caused by water treatment steps such as aeration and chlorination, increased the rate of sleeve fouling and the rate of irradiance loss within the reactor. Analysis of metals in the sleeve foulant showed that calcium and iron predominate, and relative comparisons of foulant composition to water chemistry highlighted a high affinity for incorporation into the foulant matrix for both iron and manganese, particularly after oxidizing treatment steps. Fouling behavior was observed to be in qualitative agreement with representations of the degree of saturation, relative to the metal:ligand combinations that are believed to comprise a large fraction of the foulants that accumulate on the surfaces of quartz jackets in UV systems used to treat water.     

Effect of medium-pressure UV irradiation on bromate concentrations in drinking water, a pilot-scale study

This study investigated the potential for bromate removal from drinking water on irradiation with medium-pressure UV lamps-a technique gaining considerable interest for drinking water disinfection. Waters from two different sources were spiked with 20microg/L of bromate and irradiated with UV fluences up to 718mJ/cm(2) utilizing a pilot-scale reactor (Calgon Carbon Corp.) at a flow of 76L/min (20 gallon/min). Essentially no removal was observed in one of the source waters. Limited bromate removal, up to 19%, was observed in the second source water at high UV fluences (696mJ/cm(2)) and a fluence-response relationship was clearly evident. All removals would be negligible at UV fluences anticipated for drinking water disinfection (< or =40mJ/cm(2)). Different water characteristics, in particular competitive absorption by nitrate and possibly DOC, were most likely responsible for the differences in bromate removal in the waters tested. The source water that did not show any removal had a higher nitrate concentration (4 vs. 0.1mg N/L) and also a higher DOC concentration (4.1 vs. 3.1mg C/L) than the other source water which showed 19% bromate removal.