Preparation and Evaluation of Novel Solid Chlorine Dioxide-based Disinfectant Powder in Single-pack

Objective To prepare and evaluate novel chlorine dioxide-based disinfectant powder in single-pack that is more convenient for use and transportation. Methods Orthogonal experiment was performed to determine the recipe of the disinfectant powder. Stability test, suspension quantitative bactericidal test, simulation field triM, and animal toxicity test were carded out to observe its bactericidal and toxicological effects. Results The orthogonal experiment showed that the type of water solution had no effect on the disinfectant powder and the best ratio of sodium chlorite to solid acid was 1：3. Ten grams of the disinfectant powder was fully dissolved in 20 mL water for 2 min, and diluted to 500 mL in water. After 5-10 min, the concentration of chlorine dioxide （CIO2） solution was 266 mg/L to 276 mg/L. After stored at 54℃ for 14 d, the average concentration of CIO2 was decreased by 5.03%. Suspension quantitative bactericidal test showed that the average killing logarithm （KL） value for both Staphylococcus aureus and Escherichia coli in 100 mg/L CIO2 solution for 2 min was over 5.00. In simulation field triM, the average descending KL value for Escherichia coli in the solution containing 100 mg/L CIO2 for 5 min was over 3.00. The mouse acute LD50 in the solution 5 times exceeded 5000 mg/kg. The disinfectant powder was not toxic and irritative to rabbit skin and had no mutagenic effect on mouse marrow polychromatic erythrocytes （PCE）. Conclusion The stability and bactericidal efficacy of solid chlorine dioxide-based disinfectant powder in single-pack are good. The solution containing 100 mg/L CIO2 can kill vegetative forms of bacteria. The concentration of CIO2 on the disinfecting surface of objects is 100 mg/L. The disinfectant powder is not toxic and irritative.

Comparison of Anolyte and Chlorine Dioxide for a Continuous Hot Water Disinfection in Nursing Home: A Two Years Legionnaires’ Disease Prevention

Worldwide epidemiological reports assert that drinking water is a source for infections and Legionella control represents a critical issue in healthcare settings. Chemical disinfections of water networks are control measures that need to be fine-tuned to obtain satisfactory results in large buildings over prolonged time periods. Aim of study is the evaluation of the effect of anolyte and chlorine dioxide, applied in two different hot water networks of a nursing home to manage Legionella risk. Nursing home has two buildings (A and B), with the same point of aqueduct water entrance. From June 2016, following a shock chlorination, the continuous disinfections with chlorine dioxide and anolyte were applied in hot networks of building A and B, respectively. Hot water was sampled at the central heating system and at two points of use for Legionella research, while chemical tests of manganese (Mn), iron (Fe), zinc (Zn) and trihalomethanes compounds (THM) were implemented to evaluate the disinfection by-products presence. Before chlorination Legionella pneumophila sg1 was recovered with a mean count of 2.4 × 104 CFU/L, while chemical compounds concentrations were within the law limits (Directive 98/83/EC). Then the disinfections Legionella was not recovered in both hot water plants. After the disinfection with chlorine dioxide (from June 2016 to May 2018), a statistically significant increase of iron, zinc and THM concentrations was detected in building A (p = 0.012;p = 0.004;p = 0.008). Both disinfectants appear effective against Legionella spp. growth in water network, but anolyte ensures a lower disinfection by-products release.

Removal effect on Mesocyclops leukarti and mutagenicity with chlorine dioxide

Mesocyclops leukarti of zooplankton propagates excessively in eutrophic water body and it cannot be effectively inactivated by the conventional drinking water treatment process. In order to tackle this problem, a study of removal effect on Mesocylops leukarti with chlorine dioxide in a waterworks was performed. The results showed that Mesocyclops leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide prcoxidation combined with the conventional drinking water treatment process. Higher oxidizability and molecular state of chlorine dioxide in water is the key to the inactivation of Mesocyclops leukarti. The chlorite, disinfection by-products （DBPs） of chlorine dioxide, was stable at 0.45 mg/L, which is lower than that critical value of the USEPA. GC-MS examination showed that the quantity of organic substance in the water treated by chlorine dioxide obviously decreased. Ames test further revealed that the mutagenicity was reduced by chlorine dioxide with respect to prechlorine. The propagation ofMesocyclops leukorti can be inactivated effectively and safely by chlorine dioxide pre-oxidation.

Characterization of chlorine dioxide as disinfectant for the removal of low concentration microcystins

Microcystins, which represents one kind of cancerogenic organic compounds, is abundant in eutro- phication water. The effects of reaction factors on chlorine dioxide （C102） for removal of low-concentration Micro- cystin-LR, Microcystin-RR, and Microcystin-YR in water as well as the reaction mechanisms was investigated by using enzyme-linked immunosorbent assay （ELISA） kit and gas chromatography-mass spectrometry （GC-MS）. The results showed that MC-LR, MC-RR, and MC-YR could be efficiently decomposed by C102. The degradation efficiency was shown positively correlated to the concen- tration of C102 and reaction time; while the effect of reaction temperature and pH is slight. The kinetic constants and activation energies of the reaction ofMC-LR, MC-RR, and MC-YR with C102 are determined as 459.89, 583.15, 488.43 L.（mol.min）I and 64.78, 53.01, 59.15kJ.mok1, respectively. As indicated by high performance liquid chromatography mass spectrometer （HPLC-MS） analysis, degradation should be accomplished via destruction of Adda group by oxidation, with the formation of dihydroxy substituendums as end products. This study has provided a fundamental demonstration of C102 serving as oxidizing disinfectant to eliminate microcystins from raw water source.

A comparative effect of 3 disinfectants on heterotrophic bacteria, iron bacteria and sulfate-reducing bacteria

The disinfection effect of chlorine dioxide, chlorine and their mixture on heterotrophic bacteria, iron bacteria and sulfate-reducing bacteria in circulating cooling water was studied. The results of the test indicated that high purity chlorine dioxide was the most effective biocide in the 3 disinfectants, and with a dosage of 0.5 mg/L, chlorine dioxide could obtain perfect effect. High purity chloride dioxide could have the excellent effect with the pH value of 6 to 10, and could keep it within 72 h. Chlorine and their mixture couldn’t reach the effect of chlorine dioxide.

A pilot study on using chlorine dioxide gas for disinfection of gastrointestinal endoscopes

Objectives： This pilot study of employing chlorine dioxide （CD） gas to disinfect gastrointestinal endoscopes was conducted to meet the expectations of many endoscopy units in China for a high-efficiency and low-cost disin- fectant. Methods： An experimental prototype with an active circulation mode was designed to use CD gas to disinfect gastrointestinal endoscopes. One type of testing device composed of polytetrafluoroethylene （PTFE） tubes （2 m long, inner diameter 1 mm） and bacterial carrier containers was used to simulate the channel of the endoscope. PTFE bacterial carriers inoculated with Bacillus atrophaeus with or without organic burden were used to evaluate the spor- icidal activity of CD gas. Factors including exposure dosage, relative humidity （RH）, and flow rate （FR） influencing the disinfection effect of CD gas were investigated. Moreover, an autoptic disinfecting test on eight real gastrointestinal endoscopes after clinical use was performed using the experimental prototype. Results： IRH, exposure dosage, or- ganic burden, and the FIR through the channel significantly （P〈0.05） affected the disinfection efficacy of CD gas for a long and narrow lumen. The log reduction increased as FR decreased. Treatment with 4 mg/L CD gas for 30 min at 0.8 L/min FR and 75% IRH, resulted in complete inactivation of spores. Furthermore, all eight endoscopes with a maximum colony-forming unit of 915 were completely disinfected. The cost was only 3 CNY （0.46 USD） for each endoscope. Conclusions： The methods and results reported in this study could provide a basis for further studies on using CD gas for the disinfection of endoscopes.

Effects of reductive inorganics and NOM on the formation of chlorite in the chlorine dioxide disinfection of drinking water

Chlorine dioxide(ClO_(2))disinfection usually does not produce halogenated disinfection byproducts,but the formation of the inorganic by-product chlorite(ClO^(–)_(2))is a serious consideration.In this study,the ClO^(–)_(2)formation rule in the ClO_(2)disinfection of drinking water was investigated in the presence of three representative reductive inorganics and four natural organic matters(NOMs),respectively.Fe^(2+)and S^(2–)mainly reduced ClO_(2)to ClO^(–)_(2)at low concentrations.When ClO_(2)was consumed,the ClO^(–)_(2)would be further reduced by Fe^(2+)and S^(2–),leading to the decrease of ClO^(–)_(2).The reaction efficiency of Mn^(2+)with ClO_(2)was lower than that of Fe^(2+)and S^(2–).It might be the case that Mn O 2 generated by the reaction between Mn^(2+)and ClO_(2)had adsorption and catalytic oxidation on Mn^(2+).However,Mn^(2+)would not reduce ClO^(–)_(2).Among the four NOMs,humic acid and fulvic acid reacted with ClO_(2)actively,followed by bovine serum albumin,while sodium alginate had almost no reaction with ClO_(2).The maximum ClO^(–)_(2)yields of reductive inorganics(70%)was higher than that of NOM(around 60%).The lower the concentration of reductive substances,the more ClO^(–)_(2)could be produced by per unit concentration of reductive substances.The results of the actual water samples showed that both reductive inorganics and NOM played an important role in the formation of ClO^(–)_(2)in disinfection.

Change in genotoxicity of wastewater during chlorine dioxide and chlorine disinfections and the influence of ammonia nitrogen

The effects of chlorine dioxide and chlorine disinfections on the genotoxicity of different biologically treated sewage wastewater samples were studied by umu-test.The experiment results showed that when chlorine dioxide dosage was increased from 0 to 30 mg/L,the genotoxicity of wastewater first decreased rapidly and then tended to be stable,while when the chlorine dosage was increased from 0 to 30 mg/L,the genotoxicity of wastewater changed diver sely for different samples.It was then found that ammonia nitro-gen did not affect the change of genotoxicity during chlorine dioxide disinfection of wastewater,while it greatly affected the change of genotoxicity during chlorine disin fection of wastewater.When the concentration of ammonia nitrogen was low(<10-20 mg/L),the genotoxicity of wastewater decreased after chlorine disinfection,and when the con-centration of ammonia nitrogen was high(>10-20 mg/L),the genotoxicity of wastewater increased after chlorine disinfection.

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。

过硫酸氢钾复合物和二氧化氯泡腾片对禽流感病毒、新城疫病毒消毒效果的评价

试验旨在研究过硫酸氢钾复合物和二氧化氯泡腾片对禽流感病毒、新城疫病毒的消毒效果。试验以H9亚型禽流感病毒SS株和新城疫活疫苗Ⅰ系克隆株CS2株为研究对象,通过接种鸡胚后测定病毒血凝效价,确定过硫酸氢钾复合物和二氧化氯泡腾片对2×10^(5) EID50/mL禽流感病毒和新城疫病毒的消毒效果、杀毒剂量以及杀毒时间。结果显示:过硫酸氢钾复合物及二氧化氯泡腾片均能杀灭禽流感病毒和新城疫病毒,其中二氧化氯泡腾片5 min内杀灭99.9%新城疫病毒的最低浓度为15 mg/L,但对H9亚型禽流感病毒的杀灭效果仅为60%;过硫酸氢钾5 min内杀灭99.9%新城疫病毒和H9亚型禽流感病毒的最低浓度分别为2.5 g/L和5 g/L;二氧化氯泡腾片杀灭80%禽流感病毒的最低浓度为120 mg/L,最快杀灭时间为60 min,杀灭99.9%新城疫病毒的浓度为15 mg/L,最快杀灭时间为5 min;过硫酸氢钾复合物杀灭99.9%禽流感病毒的最低浓度是5 g/L,最快杀灭时间是5 min,杀灭99.9%新城疫病毒的最低浓度是2.5 g/L,最快杀灭时间是5 min;5 g/L过硫酸氢钾复合物对发生H9亚型禽流感的养殖场临床杀灭试验显示,过硫酸氢钾复合物处理15 min后无法检测到病毒核酸。研究表明,过硫酸氢钾复合物对禽流感病毒和新城疫病毒具有较好的杀灭效果,可作为养禽场及其周围环境的消毒剂,但使用时应注意有效浓度和作用时长。

复合型二氧化氯发生器工艺优化研究

生活饮用水的安全保障是中国所面临的较大民生问题之一。针对自主研发的国产复合型二氧化氯发生器发生效率低的现状以及消毒剂在应用过程中的各种问题,通过对复合型二氧化氯发生器的发生工艺进行条件参数优化,根据氯酸钠制备法的反应机理和条件,通过研究反应物加药比、反应温度和反应时间对反应效率的影响,最终得到最佳反应条件。

基于声音空间化技术的自来水厂二氧化氯安全消毒方法

为提升自来水厂二氧化氯消毒的安全性,提出一种基于声音空间化技术的自来水厂二氧化氯安全消毒新方法。该方法采用了声波相控阵技术、超声波空化效应增强技术及声学共振耦合消毒优化技术,在降低二氧化氯使用量的同时显著提高了消毒效率和安全性。实验结果证实了该方法的可行性,为解决传统二氧化氯消毒工艺的局限提供了新思路。

二氧化氯缓释消毒剂在雏鸡孵化中的应用效果

现代雏鸡孵化过程中,仅在入孵前进行种蛋和孵化器内部的消毒,缺乏孵化过程中的消毒净化环节,造成孵化率和健雏率较低,死淘率、弱雏率和臭蛋率等指标居高不下。为了解决孵化过程中的消毒净化问题,提高孵化率、健雏率等生产指标,本试验用二氧化氯缓释消毒剂对孵化过程中种蛋和孵化箱内环境进行消毒。结果发现,二氧化氯缓释消毒剂能极显著提高受精蛋孵化率和入孵蛋健雏率(P<0.01),同时极显著降低种蛋的弱雏率和毛蛋率(P<0.01),显著降低臭蛋率(P<0.05)。综上所述,孵化过程中使用二氧化氯缓释消毒剂可有效改善种蛋的孵化效果,提高健雏率等生产性能。

二氧化氯消毒技术在医院消毒工作中的应用研究

二氧化氯是一种较为理想的优质消毒剂,具有环保、无毒的突出优势,且消毒效果明显,可以满足公共空间环境的消毒需求,尤其适用于医院消毒工作。从医院消毒工作重难点入手进行分析,讨论了二氧化氯的典型特征及消毒原理,结合医院消毒工作基本标准,探究适用于医院消毒工作的二氧化氯消毒技术实施路径,以充分发挥二氧化氯消毒技术的作业优势,实现医院消毒工作质量的有效提升。

优质水厂二氧化氯消毒稳定性技术应用优化

给水消毒是供水公司给水处理的核心问题,二氧化氯作为常用消毒剂,在饮用水净水领域中有着广泛的应用。但二氧化氯需即时制备、无法储存,且投加效果受环境影响较大,对于提升二氧化氯消毒稳定性的研究颇具发掘空间。广东某优质水厂运行至今,结合其十余年的二氧化氯消毒应用经验,总结了二氧化氯消毒稳定性应用优化实践,可供相关水厂参考。

Waste Water Disinfection During SARS Epidemic for Microbiological and Toxicological Control

Objective To evaluate the disinfection of wastewater in China. Methods During the SARS epidemic occurred in Beijing, a study of different disinfection methods used in the main local wastewater plants including means of chlorine, chlorine dioxide, ozone, and ultraviolet was carried out in our laboratory. The residual coliform, bacteria and trihalomethanes, haloacetic acids were determined after disinfection. Results Chlorine had fairly better efficiency on microorganism inactivation than chlorine dioxide with the same dosage. Formation of THMs and HAAs does not exceed the drinking water standard. UV irradiation had good efficiency on microorganism inactivation and good future of application in China. Organic material and ammonia nitrogen was found to be significant on inactivation and DBPs formation. Conclusion Chlorine disinfection seems to be the best available technology for coliform and bacteria inactivation. And it is of fairly low toxicological hazard due to the transformation of monochloramine.

Effect of chlorine dioxide on avian influenza A(H7N9)virus

Avian influenza remains a threat to human wellbeing.Hypochlorite derivatives are commonly used as disinfectants to prevent the spread of the disease.The World Health Organization(WHO)has listed chlorine dioxide(ClO_(2))as an A1‐level,safe,and efficient disinfectant.In this study,we tested the efficacy of ClO_(2),in aqueous solution and gas forms,against avian influenza A(H7N9)virus.The virus suspension was mixed with ClO_(2) aqueous solutions of various concentrations and for various time intervals.Aliquots of the mixture were then serially diluted,and the 50%tissue culture infective dose(TCID50)was measured with a hemagglutination test on MDCK cells.ClO_(2) gas produced from generators was introduced in a chamber containing the virus suspension in a Petri dish.The infective activity of the surviving virus was measured by the hemagglutination test.An aqueous solution of ClO_(2) at 126μg/mL for 15 s was effective given that no surviving virus was detected with the hemagglutination test.ClO_(2) gas at>5μL/L sustained for 1 h inactivated the virus effectively,while at 2.5μL/L for 1 h,it only partially inactivated the virus.ClO_(2) as gas or aqueous solution at a certain concentration is effective in inactivating the H7N9 virus,and can be applied for the decontamination and disinfection of environments.

Impact of combining chlorine dioxide and chlorine on DBP formation in simulated indoor swimming pools

The main objective of this study was to assess the combined use of chlorine dioxide（ClO_2）and chlorine（Cl_2） on the speciation and kinetics of disinfection by-product（DBP） formation in swimming pools using synthetic pool waters prepared with a body fluid analog（BFA）and/or fresh natural water. At 1：25（mass ratio） of ClO_2 to Cl_2, there was no significant reduction in the formation of trihalomethanes（THMs） and haloacetic acids（HAAs） for both BFA solution and natural water compared to the application of Cl_2 alone. When the mass ratio of ClO_2 to Cl_2increased to 1：1, substantial decreases in both THMs and HAAs were observed in the natural water, while there was almost no change of DBP formations in the BFA solution. Haloacetonitriles and halonitromethanes levels in both water matrices remained similar. In the presence of bromide, the overall DBP formation increased in both BFA solution and natural water. For the DBP formation kinetics, after 72 hr of contact time,very low formation of THMs and HAAs was observed for the use of ClO_2 only. Compared to Cl_2 control, however, applying the 1：1 mixture of ClO_2/Cl_2 reduced THMs by 〉 60% and HAAs by 〉 50%. Chlorite was maintained below 1.0 mg/L, while the formation of chlorate significantly increased over the reaction time. Finally, in a bench-scale indoor pool experiment, applying ClO_2 and Cl_2simultaneously produced less THMs compared to Cl_2 control and kept chlorite at 〈 0.4 mg/L, while HAAs and chlorate accumulated over 4-week operation period.

Exploration of reaction rates of chlorine dioxide with tryptophan residue in oligopeptides and proteins

Chlorine dioxide(ClO2),an alternative disinfectant to chlorine,has a superior ability to inactivate microorganisms,in which protein damage has been considered as the main inactivation mechanism.However,the reactivity of ClO2 with amino acid residues in oligopeptides and proteins remains poorly investigated.In this research,we studied the reaction rate constants of ClO2 with tryptophan residues in five heptapeptides and four proteins using stopped-flow or competition kinetic method.Each heptapeptide and protein contain only one tryptophan residue and the reactivity of tryptophan residue with ClO2 was lower than that of free tryptophan(3.88×10^4(mol/L)^-1 sec^-1 at pH 7.0).The neighboring amino acid residues affected the reaction rates through promoting inter-peptide aggregation,changing electron density,shifting pKa values or inducing electron transfer via redox reactions.A single amino acid residue difference in oligopeptides can make the reaction rate constants differ by over 60%(e.g.3.01×10^4(mol/L)^-1 sec^-1 for DDDWNDD and 1.85×10^4(mol/L)^-1 sec^-1 for DDDWDDD at pH 7.0(D:aspartic acid,W:tryptophan,N:asparagine)).The reaction rates of tryptophan-containing oligopeptides were also highly pH-dependent with higher reactivity for deprotonated tryptophan than the neutral specie.Tryptophan residues in proteins spanned a 4-fold range reactivity toward ClO2(i.e.0.84×10^4(mol/L)^-1 sec^-1 for ribonuclease T1 and 3.21×10^4(mol/L)^-1 sec^-1 for melittin at pH 7.0)with accessibility to the oxidant as the determinating factor.The local environment surrounding the tryptophan residue in proteins can also accelerate the reaction rates by increasing the electron density of the indole ring of tryptophan or inhibit the reaction rates by inducing electron transfer reactions.The results are of significance in advancing understanding of ClO2 oxidative reactions with proteins and microbial inactivation mechanisms.

基于吹扫捕集-气相色谱-质谱法探究单一/联合消毒剂消毒后生活饮用水中4种三卤甲烷生成量的变化

为探究次氯酸钠和二氧化氯+次氯酸钠消毒后生活饮用水中4种三卤甲烷[THMs,包括三氯甲烷(TCM)、二氯一溴甲烷(DCBM)、一氯二溴甲烷(DBCM)和三溴甲烷(TBM)]生成量以及生成比例的变化,进行了题示研究。将水样(稳定剂为抗坏血酸)充满40mL吹扫捕集瓶中,加入10.0mg·L^(-1)内标(氟苯)使用液10.0μL,旋紧瓶盖,振荡1 min后分取5 mL,在吹扫温度30℃、吹扫时间9.0min、吹扫流量40mL·min^(-1)、解吸温度225℃、解吸时间2.0min等条件下吹扫捕集,所得气体进入气相色谱-质谱仪,在DB-5MS石英毛细管色谱柱(60m×0.32mm,1.0μm)上进行程序升温分离(初始柱温为45℃),所得4种THMs用电子轰击离子(EI)源电离,以选择离子监测(SIM)模式检测,内标法定量。结果显示,4种THMs与内标的质量浓度比值均在一定范围内与其对应的峰面积比值呈线性关系,检出限(3s)为0.027~0.030μg·L^(-1);分别以无本底水和管网水为基质进行3个浓度水平的加标回收试验,回收率为88.1%~105%,测定值的相对标准偏差(n=6)为1.7%~4.7%。方法用于深圳市3家水厂76份生活饮用水样品中4种THMs的分析,各水厂水样中4种THMs的检出量和总量均未超过GB 5749-2022规定的限值;采用单一次氯酸钠消毒的水样中各THMs检出量占各THMs限值比值的加和(THMs*值)存在超标风险:采用二氧化氯+次氯酸钠消毒的水样中TCM的检出量和THMs总量均降低了近50%,TCM检出量占THMs总量的比值降低,其余3种溴代THMs的比值增加,并且次氯酸钠的投放量和投放次数显著降低,THMs*值超标风险降低,建议相关水厂在夏季高温多雨时,及时关注水源水质的变化,必要时采用二氧化氯+次氯酸钠联合消毒方式。