Chlorine Dioxide Disinfection Temperature Effects

S ummary . Washed suspensions of Escherichia coli were exposed to different concentrations of chlorine dioxide at various temperatures. Platings of the mixtures to evaluate the numbers of surviving cells were made after 5–300 sec of contact. Survival data were best fitted by a reaction model that is first order with respect to cell concentration and to exposure time. Bactericidal rates were found to increase markedly with both increased disinfectant concentrations and increased temperatures. Activation energies at each concentration of chlorine dioxide are reported.     

常用消毒剂次氯酸钠和二氧化氯对小林三代虫的杀灭效果

为了有效控制三代虫病, 实验以寄生于金鱼的小林三代虫(Gyrodactylus kobayashii)为动物模型, 研究了两种常用消毒剂次氯酸钠溶液(NaClO)和二氧化氯(ClO2)的杀虫效果。结果表明: 在离体(in vitro)条件下, 当NaClO的有效浓度0.2 mg/L或ClO2的有效浓度0.15 mg/L 时, 小林三代虫的平均存活时间均少于2h, 而对照组中小林三代虫的平均存活时间是20.8h。当ClO2的有效浓度0.15 mg/L时, 70%以上的虫体发黑, 而其他浓度处理组, 大部分虫体即使死亡, 虫体依然保持透明。在在体(in vivo)条件下, 当 NaClO的有效浓度0.2 mg/L或ClO2的有效浓度0.5 mg/L 时, 驱虫率都几乎达到100%, 并且驱虫率随着药物浓度的增加而提高,但当ClO2的有效浓度为0.6 mg/L时, 养殖水体出现了白色絮状物。在在体条件下, NaClO的驱虫效果好于ClO2。在金鱼的急性毒性实验中, NaClO和ClO2的安全浓度分别是0.18和0.48 mg/L, 仅稍低于其在在体条件下完全驱除小林三代虫的最小浓度(0.2、0.5 mg/L), 说明次氯酸钠溶液和二氧化氯在驱除三代虫时对金鱼不太安全, 因此, 在治疗金鱼的三代虫病时要慎使次氯酸钠溶液和二氧化氯。然而, 这两种消毒剂能否适用于其他鱼类三代虫病的治疗则有待进一步研究。     

Potentiometry of the Reaction of Residual Lignin of Lignocellulose Powder Material with Chlorine Dioxide

The consumption rate of chlorine dioxide in the reaction with the residual lignin was studied using measurements of the potential of a redox couple ClO₂/ClO ₂ ^? in an aqueous suspension of lignocellulose powder material. The methodology was developed for the study of reaction kinetics of chlorine dioxide with the residual lignin using the first order reaction model with the initial lignin concentration in the reaction medium varying in the range of (1–17) × 10^–4 М at the initial chlorine dioxide concentration of 4.48 × 10^–4 М. The monochronic rate constant of the second order reaction of chlorine dioxide with the residual lignin was calculated by the dependence k_eff(I) = k_eff(II)[L]₀ under the lignin excess conditions, it was 1462 ± 108 М^–1 s^–1. Considering the initial concentrations of reagents, it was found that, with increasing the degree of lignin conversion Θ from ≈0.27 to 0.54, its reactivity in the interaction with the chlorine dioxide is reduced, and the value of k_eff(II) decreased from ≈1280 to 900 М^–1 s^–1, which according to the theory of polychronic kinetics was a manifestation of the kinetic nonequivalence of the various ensembles of macromolecules of the residual lignin. Thus, it was experimentally shown for the first time that residual lignin of lignocellulose powder material had a kinetic nonequivalence in the interaction with chlorine dioxide.     

Effects of ozone, chlorine dioxide, chlorine, and monochloramine on Cryptosporidium parvum oocyst viability

Purified Cryptosporidium parvum oocysts were exposed to ozone, chlorine dioxide, chlorine, and monochloramine. Excystation and mouse infectivity were comparatively evaluated to assess oocyst viability. Ozone and chlorine dioxide more effectively inactivated oocysts than chlorine and monochloramine did. Greater than 90% inactivation as measured by infectivity was achieved by treating oocysts with 1 ppm of ozone (1 mg/liter) for 5 min. Exposure to 1.3 ppm of chlorine dioxide yielded 90% inactivation after 1 h, while 80 ppm of chlorine and 80 ppm of monochloramine required approximately 90 min for 90% inactivation. The data indicate that C. parvum oocysts are 30 times more resistant to ozone and 14 times more resistant to chlorine dioxide than Giardia cysts exposed to these disinfectants under the same conditions. With the possible exception of ozone, the use of disinfectants alone should not be expected to inactivate C. parvum oocysts in drinking water.     

Effects of ozone, chlorine dioxide, chlorine, and monochloramine on Cryptosporidium parvum oocyst viability.

Purified Cryptosporidium parvum oocysts were exposed to ozone, chlorine dioxide, chlorine, and monochloramine. Excystation and mouse infectivity were comparatively evaluated to assess oocyst viability. Ozone and chlorine dioxide more effectively inactivated oocysts than chlorine and monochloramine did. Greater than 90% inactivation as measured by infectivity was achieved by treating oocysts with 1 ppm of ozone (1 mg/liter) for 5 min. Exposure to 1.3 ppm of chlorine dioxide yielded 90% inactivation after 1 h, while 80 ppm of chlorine and 80 ppm of monochloramine required approximately 90 min for 90% inactivation. The data indicate that C. parvum oocysts are 30 times more resistant to ozone and 14 times more resistant to chlorine dioxide than Giardia cysts exposed to these disinfectants under the same conditions. With the possible exception of ozone, the use of disinfectants alone should not be expected to inactivate C. parvum oocysts in drinking water.     

The combined effects of various disinfectants against poliovirus 1 in a municipal wastewater effluent

Abstract The effects of the combination of any two of the following disinfectants: chlorine, chlorine dioxide, ozone and peracetic acid were investigated using poliovirus 1 as a model virus in a municipal sewage effluent. It was noted that the efficacy of chlorine was enhanced in the presence of either chlorine dioxide, ozone or peracetic acid. Maximum enhancement was achieved when peracetic acid was present with either chlorine or ozone and less enhancement was noted when the peracetic acid was added before chlorine dioxide. Similar results were noted when hydrochloric acid was used instead of peracetic acid. It may be concluded that the application of any two of the disinfectants studied were rarely synergistic but merely additive or complementary (i.e., one disinfectant provides the other with a medium in which it functions better).     

Comparative study on application of T.lanuginosus SSBP xylanase and commercial xylanase on biobleaching of non wood pulps

Biobleaching of three non wood kraft pulps (bagasse, rice straw and wheat straw) by Thermomyces lanuginosus SSBP xylanase and commercial xylanase (cartazyme sandoz), was studied in order to investigate their potential and effect on their various properties (reduction sugars, chlorine dioxide, kappa number, brightness and chromophores). In generally, xylanases released chromophores and reducing sugars and decreased kappa number of pulps. These samples gained over six brightness points over controls. Biobleaching of rice straw pulp with xylanase cartazyme (Sandoz) produced chlorine dioxide savings of up to 25% or 3.5-4 kg chlorine dioxide/ton pulp.     

Susceptibility of the brine shrimp Artemia and its pathogen Vibrio parahaemolyticus to chlorine dioxide in contaminated sea-water.

Adults and nauplii of the brine shrimp, Artemia, together with Vibrio parahaemolyticus, were placed in sewage-contaminated sea-water which had been treated with chlorine dioxide (Hallox E-100TM) to test its potential as a disinfectant for salt water aquaculture. The nauplii were very susceptible to low concentrations of chlorine dioxide (47 micrograms/l Cl-), but the adults were slightly more resistant. Sterile sea-water treated with lower concentrations of chlorine dioxide (less than 47 micrograms/l Cl-) had no effect on the shrimp, but inhibited the growth of V. parahaemolyticus. In sewage-contaminated sea-water, chlorine dioxide levels of 285-2850 micrograms/l, necessary for the inactivation of V. parahaemolyticus and any native bacteria, destroyed the Artemia culture. Hallox E-100TM persisted in sea-water for 18 h, but later decayed. We conclude that: (i) Artemia nauplii are a sensitive and convenient test-organism to determine low concentrations of chlorine dioxide in sea-water; (ii) chlorine dioxide is efficient for controlling V. parahaemolyticus in sea-water; and (iii) chlorine dioxide should be further evaluated as a potential disinfectant for aquaculture, but, for higher organisms than Artemia.     

Mechanisms of inactivation of poliovirus by chlorine dioxide and iodine.

Chlorine dioxide and iodine inactivated poliovirus more efficiently at pH 10.0 than at pH 6.0. Sedimentation analyses of viruses inactivated by chlorine dioxide and iodine at pH 10.9 showed that viral RNA separated from the capsids, resulting in the conversion of virions from 156S structures to 80S particles. The RNAs release from both chlorine dioxide- and iodine-inactivated viruses cosedimented with intact 35S viral RNA. Both chlorine dioxide and iodine reacted with the capsid proteins of poliovirus and changed the pI from pH 7.0 to pH 5.8. However, the mechanisms of inactivation of poliovirus by chlorine dioxide and iodine were found to differ. Iodine inactivated viruses by impairing their ability to adsorb to HeLa cells, whereas chlorine dioxide-inactivated viruses showed a reduced incorporation of [14C]uridine into new viral RNA. We concluded, then, that chlorine dioxide inactivated poliovirus by reacting with the viral RNA and impairing the ability of the viral genome to act as a template for RNA synthesis.     

Susceptibility of the brine shrimp Artemia and its pathogen Vibrio parahaemolyticus to chlorine dioxide in contaminated sea-water

Adults and nauplii of the brine shrimp, Artemia , together with Vibrio parahaemolyticus , were placed in sewage-contaminated sea-water which had been treated with chlorine dioxide (Hallox E-100^TM) to test its potential as a disinfectant for salt water aquaculture. The nauplii were very susceptible to low concentrations of chlorine dioxide (47 μg/1 Cl^-), but the adults were slightly more resistant. Sterile sea-water treated with lower concentrations of chlorine dioxide (less than 47 μg/1 Cl^-) had no effect on the shrimp, but inhibited the growth of V. parahaemolyticus. In sewage-contaminated sea-water, chlorine dioxide levels of 285–2850 μg/1, necessary for the inactivation of V. parahaemolyticus and any native bacteria, destroyed the Artemia culture. Hallox E-100^TH persisted in sea-water for 18 h, but later decayed. We conclude that: (i) Artemia nauplii are a sensitive and convenient test-organism to determine low concentrations of chlorine dioxide in sea-water; (ii) chlorine dioxide is efficient for controlling V. parahaemolyticus in sea-water; and (iii) chlorine dioxide should be further evaluated as a potential disinfectant for aquaculture, but, for higher organisms than Artemia.     

Inactivation of simian rotavirus SA11 by chlorine, chlorine dioxide, and monochloramine.

The kinetics of inactivation of simian rotavirus SA11 by chlorine, chlorine dioxide, and monochloramine were studied at 5 degrees C with a purified preparation of single virions and a preparation of cell-associated virions. Inactivation of the virus preparations with chlorine and chlorine dioxide was studied at pH 6 and 10. The monochloramine studies were done at pH 8. With 0.5 mg of chlorine per liter at pH 6, more than 4 logs (99.99%) of the single virions were inactivated in less than 15 s. Both virus preparations were inactivated more rapidly at pH 6 than at pH 10. With chlorine dioxide, however, the opposite was true. Both virus preparations were inactivated more rapidly at pH 10 than at pH 6. With 0.5 mg of chlorine dioxide per liter at pH 10, more than 4 logs of the single-virus preparation were inactivated in less than 15 s. The cell-associated virus was more resistant to inactivation by the three disinfectants than was the preparation of single virions. Chlorine and chlorine dioxide, each at a concentration of 0.5 mg/liter and at pH 6 and 10, respectively, inactivated 99% of both virus preparations within 4 min. Monochloramine at a concentration of 10 mg/liter and at pH 8 required more than 6 h for the same amount of inactivation.     

Inactivation of simian rotavirus SA11 by chlorine, chlorine dioxide, and monochloramine

The kinetics of inactivation of simian rotavirus SA11 by chlorine, chlorine dioxide, and monochloramine were studied at 5 degrees C with a purified preparation of single virions and a preparation of cell-associated virions. Inactivation of the virus preparations with chlorine and chlorine dioxide was studied at pH 6 and 10. The monochloramine studies were done at pH 8. With 0.5 mg of chlorine per liter at pH 6, more than 4 logs (99.99%) of the single virions were inactivated in less than 15 s. Both virus preparations were inactivated more rapidly at pH 6 than at pH 10. With chlorine dioxide, however, the opposite was true. Both virus preparations were inactivated more rapidly at pH 10 than at pH 6. With 0.5 mg of chlorine dioxide per liter at pH 10, more than 4 logs of the single-virus preparation were inactivated in less than 15 s. The cell-associated virus was more resistant to inactivation by the three disinfectants than was the preparation of single virions. Chlorine and chlorine dioxide, each at a concentration of 0.5 mg/liter and at pH 6 and 10, respectively, inactivated 99% of both virus preparations within 4 min. Monochloramine at a concentration of 10 mg/liter and at pH 8 required more than 6 h for the same amount of inactivation.     

Decontamination Efficacy and Skin Toxicity of Two Decontaminants against Bacillus anthracis

Decontamination of bacterial endospores such as Bacillus anthracis has traditionally required the use of harsh or caustic chemicals. The aim of this study was to evaluate the efficacy of a chlorine dioxide decontaminant in killing Bacillus anthracis spores in solution and on a human skin simulant (porcine cadaver skin), compared to that of commonly used sodium hypochlorite or soapy water decontamination procedures. In addition, the relative toxicities of these decontaminants were compared in human skin keratinocyte primary cultures. The chlorine dioxide decontaminant was similarly effective to sodium hypochlorite in reducing spore numbers of Bacillus anthracis Ames in liquid suspension after a 10 minute exposure. After five minutes, the chlorine dioxide product was significantly more efficacious. Decontamination of isolated swine skin contaminated with Bacillus anthracis Sterne with the chlorine dioxide product resulted in no viable spores sampled. The toxicity of the chlorine dioxide decontaminant was up to two orders of magnitude less than that of sodium hypochlorite in human skin keratinocyte cultures. In summary, the chlorine dioxide based decontaminant efficiently killed Bacillus anthracis spores in liquid suspension, as well as on isolated swine skin, and was less toxic than sodium hypochlorite in cultures of human skin keratinocytes.     

二氧化氯对小水榕外植体消毒效果研究

选取小水榕的绿芽和粗壮嫩芽组织为外植体,研究不同浓度ClO₂对外植体的消毒效果。结果表明:等于或高于500 mg/L的ClO₂溶液能迅速破坏小水榕成熟组织的绿色素;ClO₂溶液浸泡后未经无菌水冲洗的外植体污染率低,但生长缓慢,难以分化丛芽;以粗壮嫩芽组织为外植体的材料经ClO₂或HgCl₂溶液浸泡灭菌都可获得无菌外植体,建立有效的快繁体系。     

Disinfecting capabilities of oxychlorine compounds

The bacterial virus f2 was inactivated by chlorine dioxide at acidic, neutral, and alkaline pH values. The rate of inactivation increased with increasing pH. Chlorine dioxide disproportionation products, chlorite and chlorate, were not active disinfectants. As chlorine dioxide solutions were degraded under alkaline conditions, they displayed reduced viricidal effectiveness, thereby confirming the chlorine dioxide free radical as the active disinfecting species.     

Disinfecting capabilities of oxychlorine compounds.

The bacterial virus f2 was inactivated by chlorine dioxide at acidic, neutral, and alkaline pH values. The rate of inactivation increased with increasing pH. Chlorine dioxide disproportionation products, chlorite and chlorate, were not active disinfectants. As chlorine dioxide solutions were degraded under alkaline conditions, they displayed reduced viricidal effectiveness, thereby confirming the chlorine dioxide free radical as the active disinfecting species.     

Effect of chlorine dioxide gas on fungi and mycotoxins associated with sick building syndrome

The growth of indoor molds and their resulting products (e.g., spores and mycotoxins) can present health hazards for human beings. The efficacy of chlorine dioxide gas as a fumigation treatment for inactivating sick building syndrome-related fungi and their mycotoxins was evaluated. Filter papers (15 per organism) featuring growth of Stachybotrys chartarum, Chaetomium globosum, Penicillium chrysogenum, and Cladosporium cladosporioides were placed in gas chambers containing chlorine dioxide gas at either 500 or 1,000 ppm for 24 h. C. globosum was exposed to the gas both as colonies and as ascospores without asci and perithecia. After treatment, all organisms were tested for colony growth using an agar plating technique. Colonies of S. chartarum were also tested for toxicity using a yeast toxicity assay with a high specificity for trichothecene mycotoxins. Results showed that chlorine dioxide gas at both concentrations completely inactivated all organisms except for C. globosum colonies which were inactivated an average of 89%. More than 99% of ascospores of C. globosum were nonculturable. For all ascospore counts, mean test readings were lower than the controls (P < 0.001), indicating that some ascospores may also have been destroyed. Colonies of S. chartarum were still toxic after treatment. These data show that chlorine dioxide gas can be effective to a degree as a fumigant for the inactivation of certain fungal colonies, that the perithecia of C. globosum can play a slightly protective role for the ascospores and that S. chartarum, while affected by the fumigation treatment, still remains toxic.     

Mutagenic properties of spent bleaching liquors from sulphite pulps and a comparison with kraft pulp bleaching liquors

Parameters influencing the mutagenic properties of spent bleaching liquors from sulphite pulps have been studied. In addition a comparison has been made between the properties of spent liquors from sulphite and kraft pulp bleaching. In the sulphite process the cooking base had no influence on the mutagenicity of the chlorination stage. In contrast, removing the extractives before chlorination especially for dissolving pulp resulted in an increase in mutagenic activity. The mutagenicity decreased significantly after substituting 40% of the chlorine with chlorine dioxide. Sequential addition of chlorine and chlorine dioxide resulted in higher activity than simultaneous or premixed chlorination as observed for liquors from kraft pulp. Increasing the pH of the extracts or addition of sulphur dioxide decreased the mutagenicity. Expressed as 10(7) revertants per kappa number and ton pulp the mutagenicity varied between 10 and 40 for sulphite pulp while the corresponding figures for kraft pulp were 100-225.     

Chlorine dioxide inactivation of Cryptosporidium parvum oocysts and bacterial spore indicators.

Cryptosporidium parvum, which is resistant to chlorine concentrations typically used in water treatment, is recognized as a significant waterborne pathogen. Recent studies have demonstrated that chlorine dioxide is a more efficient disinfectant than free chlorine against Cryptosporidium oocysts. It is not known, however, if oocysts from different suppliers are equally sensitive to chlorine dioxide. This study used both a most-probable-number-cell culture infectivity assay and in vitro excystation to evaluate chlorine dioxide inactivation kinetics in laboratory water at pH 8 and 21 degrees C. The two viability methods produced significantly different results (P < 0.05). Products of disinfectant concentration and contact time (Ct values) of 1,000 mg. min/liter were needed to inactivate approximately 0.5 log(10) and 2.0 log(10) units (99% inactivation) of C. parvum as measured by in vitro excystation and cell infectivity, respectively, suggesting that excystation is not an adequate viability assay. Purified oocysts originating from three different suppliers were evaluated and showed marked differences with respect to their resistance to inactivation when using chlorine dioxide. Ct values of 75, 550, and 1,000 mg. min/liter were required to achieve approximately 2.0 log(10) units of inactivation with oocysts from different sources. Finally, the study compared the relationship between easily measured indicators, including Bacillus subtilis (aerobic) spores and Clostridium sporogenes (anaerobic) spores, and C. parvum oocysts. The bacterial spores were found to be more sensitive to chlorine dioxide than C. parvum oocysts and therefore could not be used as direct indicators of C. parvum inactivation for this disinfectant. In conclusion, it is suggested that future studies address issues such as oocyst purification protocols and the genetic diversity of C. parvum, since these factors might affect oocyst disinfection sensitivity.     

Measurement of chlorine dioxide penetration in dairy process pipe biofilms during disinfection

Biofilms are considered a significant health risk in the food and dairy industries because they can harbor pathogens, and direct contact with them can lead to food contamination. Biofilm control is often performed using strong oxidizing agents like chlorine and peracetic acid. Although chlorine dioxide (ClO₂) is being used increasingly to control microbiological growth in a number of different industries, not much is known about disinfection in biofilms using chlorine dioxide. In this study, a microelectrode originally made for chlorine detection was modified to measure the profiles of chlorine dioxide in biofilm as a function of depth into the biofilm. In addition, discarded microelectrodes proved useful for in situ direct measurement of biofilm thicknesses. The chlorine dioxide microelectrode had a linear response when calibrated up to a ClO₂ concentration of 0.4 mM. ClO₂ profiles showed depletion of disinfectant at 100 μm in the biofilm depth, indicating that ClO₂ may not reach bacteria in a biofilm thicker than this using a 25 mg/l solution.