Suspended particle effects on ClO_2/ultraviolet light combined disinfection of effluent

The concentration of suspended solids of effluent often varies in a wide range, therefore the dose of ultraviolet light （UV） in disinfection process needs to be adjusted to meet the disinfection criterion at a high frequency, and the desired disinfection effect is difficult to be ensured. The particles size and particle-associated fecal coliform （F.C.） contribution, and their influence on UV disinfection were investigated when ClO2 and UV combined disinfection process was used. The results showed that suspended solids content had a major impact on UV disinfection efficiency, especially the large particle size fraction. Particles （D〉10μm） associated F. C. were difficult to be disinfected and were the main part of the railings of F.C. inactivation curve. Pre-ClO2 oxidation could reduce the number of particles in effluent, and make large particles decrease to small ones. Therefore, the influence of particles on UV disinfection could be reduced after pre-ClO2 oxidation, and the resistance ability to particle loadings of combined process was enhanced. Moreover, the combined process has a lot of advantages, such as low toxicity, low operational/maintenance costs; it is also convenient to be established in the existing wastewater plant or the new planned one.

Double enzyme mimetic activities of multifunctional Ag nanoparticle-decorated Co_(3)V_(2)O_(8)hollow hexagonal prismatic pencils for application in colorimetric sensors and disinfection

Since the catalytic activity of most nanozymes is still far lower than the corresponding natural enzymes,there is urgent need to discover novel highly efficient enzyme-like materials.In this work,Co_(3)V_(2)O_(8)with hollow hexagonal prismatic pencil structures were prepared as novel artificial enzyme mimics.They were then decorated by photo-depositing Ag nanoparticles(Ag NPs)on the surface to further improve its catalytic activities.The Ag NPs decorated Co_(3)V_(2)O_(8)(ACVPs)showed both excellent oxidase-and peroxidase-like catalytic activities.They can oxidize the colorless 3,3’,5,5’-tetramethylbenzidine rapidly to induce a blue change.The enhanced enzyme mimetic activities can be attributed to the surface plasma resonance(SPR)effect of Ag NPs as well as the synergistic catalytic effect between Ag NPs and Co_(3)V_(2)O_(8),accelerating electron transfer and promoting the catalytic process.ACVPs were applied in constructing a colorimetric sensor,validating the occurrence of the Fenton reaction,and disinfection,presenting favorable catalytic performance.The enzyme-like catalytic mechanism was studied,indicating the chief role of⋅O_(2)-radicals in the catalytic process.This work not only discovers a novel functional material with double enzyme mimetic activity but also provides a new insight into exploiting artificial enzyme mimics with highly efficient catalytic ability.

气体ClO_2对葡萄致腐菌的杀菌及保鲜效果研究

以巨峰葡萄为试材,研究气体ClO2浓度和作用时间对接种于葡萄表面的灰葡萄霉菌、青霉和交链孢霉的杀菌效果的影响。结果表明,气体ClO2对接种于葡萄表面的3种霉菌具有良好的杀菌效果,杀菌率随气体ClO2浓度增加和处理时间的延长而提高。在气体ClO2浓度为10 mg/m3,杀菌时间为40 min条件下,灰葡萄霉菌、青霉及交链孢霉均减少了3.23 log.cfu/g以上。同时研究经气体ClO2处理后的葡萄,并将葡萄贮藏在温度为(2±0.5)℃,湿度为(95±1)%的恒温恒湿箱内,在贮藏期内,定期检测葡萄腐烂率、丙二醛的含量及主要营养成分。结果表明:此实验条件下可有效降低果实的腐烂率、减少VC、还原糖和可滴定酸的消耗,使果实保持较好的外观和风味,起到较好的保鲜效果。

絮凝-ClO_2消毒氧化法处理洗浴废水

利用絮凝 -ClO2 消毒氧化法对洗浴废水进行了以回用为目的的实验研究 .结果表明 ,对于浊度为 2 0度、CODCr32 0mg/L、细菌总数 36 0 0个 /mL、大肠杆菌 35 0个 /mL的每吨废水 ,当絮凝剂 (本文所用为一复合絮凝剂 )用量为 2 5 0 g、ClO2 用量 2 0 g ,在适当的反应条件下 ,可使处理后水的浊度达到 1.7度、CODCr17.5mg/L、细菌总数 <10 0个 /mL、大肠杆菌 <3个 /L ,能够达到回用的要求 .同时对此工艺进行了经济效益分析 .

响应面法优化ClO_2溶液对牡蛎中沙门氏菌的杀菌动力学

为了探究ClO_2溶液处理牡蛎中沙门氏菌的最佳杀菌条件,本文选用鼠伤寒沙门氏菌(CICC22956)和肠炎沙门氏菌(CICC21482)混合菌株,在单因素实验的基础上,运用响应面实验设计方法探讨料液比、ClO_2溶液浓度和杀菌时间对牡蛎中的沙门氏菌杀菌效果的影响。通过响应面优化模型确定ClO_2溶液杀菌的最佳条件为:料液比1∶7g/mL,ClO_2浓度93g/mL,杀菌时间30min。在此条件下模型优化出最优的沙门氏菌菌落降低值为3.13lgcfu/g。实验结果表明,采用上述分析的最佳条件不仅有效防止牡蛎中沙门氏菌的污染,还可以提高生鲜牡蛎的品质和安全性。

An ab initio study on single electron transfer between ClO_2 and phenol

The SET mechanism between chlorine dioxide （ClO2） and phenol was studied by using ab initio method at 4-31G* level. Geometries of the reactants, intermediate and products of the reaction were optimized and the single point energy calculations of the species were performed. The relative structure data of the reactants, intermediate and products are given.The SET mechanism between ClO2and phenol was confirmed by ab initio calculations. The reaction is exothermic about 200 88 kJ/mol.

Disinfection of dairy wastewater effluent through solar photocatalysis processes

Due to the strict regulations and reuse policies that govern wastewater's use as an irrigation water resource for agricultural purposes, especially in dry climates, optimization of the disinfection process is of the utmost importance. The effects of solar radiation along with Titanium dioxide(TiO_2) nanoparticles applied to optimization of the photolysis and photocatalysis processes for inactivating heterotrophic bacteria were investigated. Temperature, p H, and dissolved oxygen fluctuations in the dairy wastewater effluent treated by activated sludge were examined. In addition,different dosages of TiO_2 were tested in the solar photocatalysis(ph-C S) and concentrated solar photocatalysis(ph-C CS) processes. The results show that the disinfection efficiencies of the solar photolysis(ph-L S) and concentrated solar photolysis(ph-L CS) processes after 30 min were about 10.5% and 68.9%, respectively, and that the ph-C S and ph-C CS processes inactivated 41% and 97% of the heterotrophic bacteria after 30 min, respectively. The p H variation in these processes was negligible. Using the ph-L CS and ph-C CS processes, the synergistic effect between the optical and thermal inactivation caused complete disinfection after three hours. However, disinfection was faster in the ph-C CS process than in the ph-L CS process. Significant correlations were found between the disinfection efficiency and the variation of the dissolved oxygen concentration in the ph-C S and ph-C CS processes, while the correlations between the disinfection efficiency and temperature variation were not significant in the ph-L S and ph-C S processes. Moreover, the oxygen consumption rate was greatest(3.2 mg··L^(-1)) in the ph-C CS process. Hence,it could be concluded that the ph-C CS process is an efficient photocatalysis process for disinfection of dairy wastewater effluent.

Disinfection Kinetics and Contribution of Reactive Oxygen Species When Eliminating Bacteria with TiO_(2) Induced Photocatalysis

Titania (TiO2) induced photocatalysis has been widely investigated and applied as a disinfection strategy in many industrial and clinical applications. Reactive oxygen species (ROS), including hydroxyl radicals (&8226OH), superoxide radicals () and hydrogen peroxide (H2O2), generated in the photocatalytic reaction process are considered to be the active components prompting the bactericidal effect. In the present work, the kinetics of photocatalytic inactivation of Staphylococcus epidermidis and specific contributions of &#8226OH, and H2O2 to the bactericidal process were studied using two disinfection settings sutilizing photocatalytic resin-TiO2 nanocomposite surfaces and suspended TiO2 nanoparticles, respectively. In antibacterial tests against S. epidermidis with a layer of bacterial suspension on the resin-TiO2 surfaces, H2O2 was found to be the most efficient ROS component contributing to the antibacterial effect. Disinfection kinetics showed a two-step behavior with an initial region having a lower disinfection rate followed by a higher rate region after 10 min of UV irradiation. By contrast, in antibacterial tests with suspended bacteria and photocatalytic TiO2 nanoparticles, &#8226OH and H2O2 showed equal significance in the bacterial inactivation having a typical Chick-Watson disinfection kinetics behavior with a steady disinfection rate. The results contribute to the understanding of the bactericidal mechanism and kinetics of photocatalytic disinfection that are essential for designing specific antibacterial applications of photocatalytic materials.

UV-TiO_2 photocatalytic disinfection and photoreactivation of pathogenic bacterium in municipal wastewater

The disinfected bacteria will be a photoreactivation under the irradiation of the sunlight,and the light intensity plays an important role in the bacteria resurrection.The effect of light intensity on photoreactivation of Escherichia coli(E.coli) and Enterococcus faecalis(E.faecalis) in secondary effluents which were disinfected respectively by pure UV and UV-TiO_2 was investigated.The results show that the disinfection efficiency of UV-TiO_2 is much higher than that of the pure UV disinfection.The photoreactivation rate of E.coli is much higher in pure UV disinfection than in UV-TiO_2 photocatalytic disinfection.Under high light intensity in UV-TiO_2 disinfection,high resurrection rate can be induced.However,a higher resurrection rate can be introduced even under low light intensity in pure UV disinfection alone.Meanwhile,UV-TiO_2 disinfection has a strong inhibition effect on E.faecalis photoreactivation.When the light intensity is lower than 21 μW/cm^2,nearly no resurrection of E.faecalis occurs after 72 h resurrection irradiation,and a little resurrection rate is observed only under a strong photoreactivating light intensity.

Skin Disinfection with 2% Chlorine Gluconate-Adine in Autologous Peripheral Hematopoietic Stem Cell Transplantation Patients

Background: Autologous peripheral blood hematopoietic stem cell transplantation is widely used in the treatment of malignant lymphoma. Patients are prone to infection during the transplantation immune deficiency period. There has been a lot of clinical research into how to better manage this period of vulnerability. Objective: This study aims to investigate the efficacy of 2% chlorhexidine gluconate (CHG) for skin disinfection in patients undergoing autologous hematopoietic stem cell transplantation (HSCT) and observe any adverse reactions. Methods: A total of 106 patients receiving autologous hematopoietic stem cell transplantation from November 2019 to December 2020 in our district were selected as the control group. From January 2021 to January 2022, 106 patients with autologous hematopoietic stem cells were included in the experimental group. The control group used the immersion bath method. The experimental group was treated with an improved scrub bath method (including 3M 2% chlorhexidine gluconate medical sanitary wipes to wipe the whole skin once). Results: The bacteria-carrying rate of the improved method (37.74%) was significantly better than that of the traditional soaking method (72.64%), and the difference was statistically significant (P Conclusion: The improved bath/wipe method has a significant positive effect on skin disinfection for patients undergoing HSCT.

化学法生产ClO_2及其在饮用水处理中的应用

主要介绍了化学法生产ClO2 的原理 ,及其在饮用水消毒中的系统设计、运行情况和使用效果。

Design and Realization of a UV-C Based Disinfection Tools Monitored by Mobile Application

In many outbreaks, patients and healthcare workers are particularly at risk from nosocomial infections as a result of non-effective disinfection methods. With increasing incidence of viral infections such as severe acute respiratory syndrome, in one hand, and the increase in the rate of antibiotic resistant bacteria associated with nosocomial infections in other hand, there is a need to design novel engineering tools for inactivation of nosocomial pathogens. Ultraviolet germicidal irradiation (UVGI) is considered as a promising method to inactivate bacteria and viruses. This paper presents UV-C Based disinfection tools monitored by mobile application, designed for hospital and Epidemic Treatment Center. The evolution of the irradiation intensity over time was evaluated, and the theorical disinfection duration for several nosocomial pathogens was determined. In the case of SARS-CoV2, less than 12 minutes were needed to achieve 99.99% viral reduction in a room of 36 sqm.

气调袋包装结合ClO_(2)对鲜切西兰花冷藏保鲜效果影响

目的研究气调袋包装结合ClO_(2)来延缓冷藏条件下鲜切西兰花的黄化和腐烂,以期维持鲜切西兰花营养品质的影响。方法以鲜切西兰花为实验材料,设CK、气调袋包装、0.5g-ClO_(2)和气调袋包装+0.5g-ClO_(2)4个处理。结果在4℃贮藏下,根据品质指标、抗氧化指标及微生物指标可知,相较于单独使用气调袋包装和0.5g-ClO_(2)处理,二者结合处理能更明显地降低鲜切西兰花的质量损失率、腐烂率、相对电导率、丙二醛、O_(2)^(-)·、H^(2)O_(2)含量及菌落总数,维持更高水平的可溶性固形物、叶绿素含量及抗氧化酶活性,具有维持细胞膜完整性,延缓失绿黄化现象及提高抗氧化能力的作用,能最有效地维持鲜切西兰花贮藏品质。结论在4℃下,利用气调袋包装+0.5g-ClO_(2)处理能显著地抑制鲜切西兰花营养成分的损失,提高其抗氧化性,延长贮藏保鲜期,可将保鲜期延长至20d,维持较好的应用价值,且具有较好的经济性与可行性。

预水解硫酸盐竹浆的漂白工艺研究

本研究以预水解硫酸盐未漂竹浆为原料,采用“氧脱木质素(O)-氯漂(D0)-氧和过氧化氢强化碱抽提(Eop)-氯漂(D_(1))”的漂白工艺制备可用作溶解浆的竹浆。通过优化各工段的处理条件(氧漂白段:氢氧化钠用量2.0%、氧压0.5 MPa、反应时间60 min、反应温度95℃;D0漂白段:二氧化氯用量3.5%、反应时间80 min、反应温度70℃、初始pH值4.0;Eop漂白段:过氧化氢用量1.4%、氧压0.2 MPa、反应时间90 min、反应温度90℃、初始pH值11.5;D1漂白段:二氧化氯用量1.5%、反应时间150 min、反应温度70℃、初始pH值4.0),最终制备白度82.7%、黏度440.0 mL/g、灰分含量0.24%、α-纤维素含量90.92%的竹浆。

模拟太阳光/ClO_(2)高级氧化技术降解卡马西平及其水环境适用性

基于ClO_(2)光解的高级氧化技术在微污染物去除方面得到了广泛研究,一般通过ClO_(2)光解产生的活性物种(Cl·、ClO·、^(1)O_(2)、O_(3)和HO·等)来实现水体中目标污染物的降解.抗癫痫药卡马西平(CBZ)难以被生物降解和自然光降解,在水环境中具有持久性.该文系统研究了模拟太阳光/ClO_(2)体系中活性物种对CBZ去除效率及降解路径的影响,同时评估了水基质(如pH的变化及Cl^(-)、HCO_(3)^(-)、腐殖酸和富里酸等的存在)对污染物降解效率的影响.研究结果表明^(1)O_(2)、O_(3)和HO·等在CBZ降解过程中发挥重要作用,模拟太阳光/ClO_(2)体系中CBZ降解效率随着pH的增大而减小,Cl^(-)的存在对CBZ降解影响较小,HCO_(3)^(-)的存在不利于CBZ降解,天然有机质中的腐殖酸对CBZ降解的抑制作用要大于富里酸,水体中K^(+)、Ca^(2+)、Mg^(2+)等阳离子的存在不影响CBZ降解效率.

新型纳米二氧化钛光触媒消毒剂的多功能应用与安全性

纳米二氧化钛因其优良的光电属性在光催化消毒杀菌领域有着良好的应用前景。然而,需要紫外光的条件极大地限制了其应用。近年来,科学家们设计了一系列各式各样的修饰,主要有贵金属/常规金属颗粒修饰、氮掺杂、碳-二氧化钛纳米材料复合、与其他半导体纳米材料形成异质结,极大地提高了纳米二氧化钛对可见光的利用率。本文对近年来新型纳米二氧化钛光触媒消毒剂的修饰种类、多功能应用和安全性等进行综述;强调修饰的新型纳米二氧化钛光触媒消毒剂具有多功能性,不仅具有优良的抗菌性,还有消除有机污染物、有毒重金属和杀虫的功能。然而,材料的回收利用困难和选择修饰元素不妥,可能带来生物安全性问题,是纳米光触媒安全应用需要考虑的问题。本综述可为纳米二氧化钛光触媒消毒剂的安全和高效应用提供参考。

在线超滤-离子色谱法同时测定生活饮用水5种消毒副产物

为了同时测定生活饮用水中的5种消毒副产物DCAA,TCAA,ClO_(2)^(-),BrO_(3)^(-)和ClO_(3)^(-)的含量,旨在构建一种高效便捷的在线超滤-离子色谱法。通过使用Metrohm metrosep a supp18-250型色谱柱,淋洗液结合浓度为14 mmol/L NaOH淋洗液,流速0.6 mL/min,以及质量分数为1%H_(2)SO_(4)抑制器再生液,运用英蓝在线超滤技术,可有效地对生活饮用水中的三氯乙酸(CCl_(3)COO^(-))(TCAA)、二氯乙酸(CHCl_(2)COO^(-))(DCAA)、亚氯酸盐(ClO_(2)^(-))、氯酸盐(ClO_(3)^(-))、溴酸盐(BrO_(3)^(-))进行分离检测,且同时进行其方法线性、准确度、精密度、检出限、定量限及加标回收率的检测。通过试验发现,标准曲线相关系数远高于0.995,相对标准偏差不超过3%。此外,加标回收率介于96.7%~102.7%,在37 min内,就能够完成5种生活水体中的消毒副产物的分析,每个物质组分检测灵敏度极高,检测周期极短,分析效率很高,因此适用于大规模的生活饮用水的测试。

包装饮用水微生物及消毒副产物的控制与平衡

在包装饮用水生产中,利用氯化手段灭菌消毒会产生三卤甲烷等有机消毒副产物,而采用二氧化氯会导致亚氯酸盐等无机消毒副产物增加;紫外线(UV)照射对水杀菌时会形成亚硝酸盐,产品中加臭氧抑菌将增加溴酸盐风险。文章重点讨论各消毒杀菌手段对水体成分的影响,研究消毒副产物之间的机理和转化关系;采用消毒剂精准投加且无残留冲洗、UV照射剂量控制及硝酸盐安全界限、缩小臭氧作用时间等工艺改进方法,从而降低消毒副产物的风险。对照欧盟控菌标准,从尊重与保护水的天然特性和全过程卫生控制出发,结合包装水工厂实操,适度消毒,平衡微生物控制与消毒副产物产生的关系。

不同消毒剂作用下再生水管网水质变化规律研究

再生水中富含微生物和各种有机质等物质,微生物大量生长繁殖容易引起水质恶化。通常采用投加消毒剂来控制微生物的增长,但消毒剂的投加会显著改变输送水的水质,进而通过水质的影响改变微生物、管壁腐蚀形态和结构。因此,研究了投加不同质量浓度(1、2、4 mg/L)的NaClO和ClO_(2)对再生水管网系统输送水的pH、DO质量浓度、电导率、阴离子质量浓度、氧化还原电位、总铁质量浓度和浊度变化的影响,研究结果为再生水厂消毒剂的选择提供了理论基础。

二氧化氯无机消毒副产物的控制现状

二氧化氯(ClO_(2))处理饮用水生成的无机消毒副产物亚氯酸盐(ClO_(2)(-))和氯酸盐(ClO-3)对人体健康有潜在危害,引起了世界范围的强烈关注。目前,国内外对控制ClO_(2)无机消毒副产物已有广泛研究。文章总结了ClO_(2)无机消毒副产物的各类来源,并针对性从发生器优化、反应过程控制以及生成后去除3方面,详细讨论了饮用水ClO_(2)无机消毒副产物的控制研究进展。文中提出在源头控制中“优选反应器、优化杂氯”,在消毒过程中“多种方式结合”,以控制无机消毒副产物的生成。此外,消毒后可使用活性炭、Fe^(2+)、硫化物、氧化法等技术去除无机消毒副产物。最后总结了当前研究存在的问题,并展望了未来研究的发展方向。