Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.435
Filtrar
1.
Environ Monit Assess ; 192(7): 422, 2020 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-32519186

RESUMO

Chlorine dioxide has been reported as very efficiently removing pesticides and other organic compounds from water matrixes. Due to pesticide toxicity and potential toxicity of their degradation products, it is important to monitor these compounds as environmental pollutants in ground and surface waters. Evaluating the effects of chlorine dioxide treatment is necessary, and toxicity studies are used to ascertain the severity of effects of intermediates due to incomplete degradation of the parent compounds. In this paper, for the first time, chlorine dioxide is applied and evaluated for the removal of chloroacetamide herbicides (pethoxamid and metazachlor) from waters (deionized water and Sava River water). The degradation degree of herbicides was measured by high-performance liquid chromatography, the main degradation products were identified using gas chromatography with a triple quadrupole mass detector, and the degree of mineralization was monitored by total organic carbon analysis. Four and two degradation products were identified after pethoxamid and metazachlor degradation, respectively. Total organic carbon analysis showed mineralization occurred, but it was incomplete. The mineralization and the characteristics of the degradation products obtained were tested using Daphnia magna and showed lower toxicity than the parent herbicides. The advantage of the applied treatment was a very high degradation percentage for pethoxamid removal from deionized water and Sava River water (100% and 97%, respectively), with higher mineralization efficiency (65%) than metazachlor. Slightly lower degradation efficiency in the Sava River water was due to chlorine dioxide oxidizing the herbicides and dissolved organic matter simultaneously.


Assuntos
Acetamidas , Compostos Clorados , Óxidos , Poluentes Químicos da Água , Purificação da Água , Acetamidas/análise , Acetamidas/química , Acetamidas/metabolismo , Acetamidas/toxicidade , Animais , Compostos Clorados/química , Daphnia/efeitos dos fármacos , Ecotoxicologia , Óxidos/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidade , Purificação da Água/métodos
2.
Food Chem ; 328: 127121, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32474241

RESUMO

Chlorine dioxide (ClO2) gas was utilized for detoxifying aflatoxin B1 (AFB1) in corn for the first time. Four degradation compounds were identified by LC-MS as C17H13O8, C17H15O10, C16H15O10, and C15H11O8. Structurally, the biological activity of ClO2-treated AFB1 was removed due to the disappearance of C8-C9 double bond in the furan ring and the modification of cyclopentanone and methoxy after ClO2 treatment. The cell viability assay on human embryo hepatocytes confirmed little toxicity of the degradation products. The degradation efficiency of AFB1 on corn peaked near 90.0% under the optimized conditions and reached 79.6% for low initial contamination of AFB1 at 5-20 µg/kg. Accordingly, ClO2 has the potential to be developed into an effective, efficient, and economic approach to detoxify AFB1 in grains.


Assuntos
Aflatoxina B1/química , Compostos Clorados/química , Cloro/química , Óxidos/química , Zea mays/química , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas
3.
J Environ Sci (China) ; 93: 129-136, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32446448

RESUMO

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 × 104 (mol/L)-1sec-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 × 104 (mol/L)-1sec-1 for DDDWNDD and 1.85 × 104 (mol/L)-1sec-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 × 104 (mol/L)-1sec-1 for ribonuclease T1 and 3.21 × 104 (mol/L)-1sec-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.


Assuntos
Compostos Clorados , Triptofano , Cloro , Oligopeptídeos , Óxidos
4.
Environ Sci Pollut Res Int ; 27(21): 27147-27160, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32399889

RESUMO

Chlorine dioxide (ClO2) degradation of the organophosphorus pesticides azamethiphos (AZA) and dimethoate (DM) (10 mg/L) in deionized water and in Sava River water was investigated for the first time. Pesticide degradation was studied in terms of ClO2 level (5 and 10 mg/L), degradation duration (0.5, 1, 2, 3, 6, and 24 h), pH (3.00, 7.00, and 9.00), and under light/dark conditions in deionized water. Degradation was monitored using high-performance liquid chromatography. Gas chromatography coupled with triple quadrupole mass detector was used to identify degradation products of pesticides. Total organic carbon was measured to determine the extent of mineralization after pesticide degradation. Real river water was used under recommended conditions to study the influence of organic matter on pesticide degradation. High degradation efficiency (88-100% for AZA and 85-98% for DM) was achieved in deionized water under various conditions, proving the flexibility of ClO2 degradation for the examined organophosphorus pesticides. In Sava River water, however, extended treatment duration achieved lower degradation efficiency, so ClO2 oxidized both the pesticides and dissolved organic matter in parallel. After degradation, AZA produced four identified products (6-chlorooxazolo[4,5-b]pyridin-2(3H)-one; O,O,S-trimethyl phosphorothioate; 6-chloro-3-(hydroxymethyl)oxazolo[4,5-b]pyridin-2(3H)-one; O,O-dimethyl S-hydrogen phosphorothioate) and DM produced three (O,O-dimethyl S-(2-(methylamino)-2-oxoethyl) phosphorothioate; e.g., omethoate; S-(2-(methylamino)-2-oxoethyl) O,O-dihydrogen phosphorothioate; O,O,S-trimethyl phosphorodithioate). Simple pesticide degradation mechanisms were deduced. Daphnia magna toxicity tests showed degradation products were less toxic than parent compounds. These results contribute to our understanding of the multiple influences that organophosphorus pesticides and their degradation products have on environmental ecosystems and to improving pesticide removal processes from water.


Assuntos
Praguicidas , Poluentes Químicos da Água , Purificação da Água , Animais , Compostos Clorados , Dimetoato , Ecossistema , Organotiofosfatos , Óxidos
5.
J Food Sci ; 85(5): 1411-1417, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32249422

RESUMO

Tiger frog (Rana tigrina) meat is extremely perishable. This study investigated the antimicrobial efficacy of chlorine dioxide (ClO2 ) on frog meat, optimized the formulation of a phosphate-based enhancement solution by response surface methodology (RSM), and determined the quality parameters (i.e., total aerobic counts [TAC], pH, drip loss, cooking loss, color measurements, shear force, total volatile basic nitrogen [TVB-N], and thiobarbituric acid-reactive substances [TBARS]) of refrigerated frog meat pretreated with ClO2 and the optimized blend of phosphates. Treatments of frog meat with 35 and 70 ppm ClO2 for 3, 5, and 10 min achieved a 0.7-, 0.9- and 0.9-, and 0.8-, 1.4- and 1.6-log CFU/g reduction of TAC, respectively, indicating the antimicrobial efficacy of ClO2 was concentration- and time-dependent with such that higher concentrations and/or longer exposure time achieved greater bacterial reductions. The concentrations of the phosphates, including sodium tripolyphosphate (STPP), sodium pyrophosphate (SPP), and sodium hexametaphosphate (SHMP), were optimized as the formula of 0.3% STPP and 0.45% SPP obtaining the highest water retention of the frog meat. After washed with 70 ppm ClO2 for 10 min and subsequently soaked with 0.3% STPP and 0.45% SPP for 30 min, the frog meat stored at 4 °C shown significantly (P < 0.05) lower TAC (<4.4 log CFU/g) and higher water holding capacity during the whole storage of 12 days, compared to the control. Results indicated that the two-step process may be applicable to slow down deterioration and maintain quality frog meat during refrigeration. PRACTICAL APPLICATION: This research provides a means to slow down deterioration, maintain quality frog meat, and improve stability during refrigeration. Refrigerated frog meat products, which are preferred by consumers with juicier and more tender texture compared to the frozen-thawed meat, could be developed by the frog industry based on the data from this study.


Assuntos
Compostos Clorados/análise , Conservação de Alimentos/métodos , Conservantes de Alimentos/análise , Carne/análise , Óxidos/análise , Fosfatos/análise , Animais , Culinária , Difosfatos/análise , Conservação de Alimentos/instrumentação , Armazenamento de Alimentos , Polifosfatos/análise , Ranidae , Refrigeração , Substâncias Reativas com Ácido Tiobarbitúrico/análise , Água/análise
6.
Physiol Int ; 107(1): 1-11, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: covidwho-18420

RESUMO

Motivation: Viruses have caused many epidemics throughout human history. The novel coronavirus [10] is just the latest example. A new viral outbreak can be unpredictable, and development of specific defense tools and countermeasures against the new virus remains time-consuming even in today's era of modern medical science and technology. In the lack of effective and specific medication or vaccination, it would be desirable to have a nonspecific protocol or substance to render the virus inactive, a substance/protocol, which could be applied whenever a new viral outbreak occurs. This is especially important in cases when the emerging new virus is as infectious as SARS-CoV-2 [4]. Aims and structure of the present communication: In this editorial, we propose to consider the possibility of developing and implementing antiviral protocols by applying high purity aqueous chlorine dioxide (ClO2) solutions. The aim of this proposal is to initiate research that could lead to the introduction of practical and effective antiviral protocols. To this end, we first discuss some important properties of the ClO2 molecule, which make it an advantageous antiviral agent, then some earlier results of ClO2 gas application against viruses will be reviewed. Finally, we hypothesize on methods to control the spread of viral infections using aqueous ClO2 solutions.


Assuntos
Betacoronavirus , Compostos Clorados/farmacologia , Doenças Transmissíveis Emergentes , Infecções por Coronavirus , Transmissão de Doença Infecciosa/prevenção & controle , Óxidos/farmacologia , Pandemias , Pneumonia Viral , Antivirais/farmacologia , Betacoronavirus/efeitos dos fármacos , Betacoronavirus/patogenicidade , Betacoronavirus/fisiologia , Protocolos Clínicos , Doenças Transmissíveis Emergentes/prevenção & controle , Doenças Transmissíveis Emergentes/virologia , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/prevenção & controle , Infecções por Coronavirus/transmissão , Infecções por Coronavirus/virologia , Desinfetantes/farmacologia , Humanos , Pandemias/prevenção & controle , Soluções Farmacêuticas/farmacologia , Pneumonia Viral/epidemiologia , Pneumonia Viral/prevenção & controle , Pneumonia Viral/transmissão , Pneumonia Viral/virologia , Projetos de Pesquisa
7.
Physiol Int ; 107(1): 1-11, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-32208977

RESUMO

Motivation: Viruses have caused many epidemics throughout human history. The novel coronavirus [10] is just the latest example. A new viral outbreak can be unpredictable, and development of specific defense tools and countermeasures against the new virus remains time-consuming even in today's era of modern medical science and technology. In the lack of effective and specific medication or vaccination, it would be desirable to have a nonspecific protocol or substance to render the virus inactive, a substance/protocol, which could be applied whenever a new viral outbreak occurs. This is especially important in cases when the emerging new virus is as infectious as SARS-CoV-2 [4]. Aims and structure of the present communication: In this editorial, we propose to consider the possibility of developing and implementing antiviral protocols by applying high purity aqueous chlorine dioxide (ClO2) solutions. The aim of this proposal is to initiate research that could lead to the introduction of practical and effective antiviral protocols. To this end, we first discuss some important properties of the ClO2 molecule, which make it an advantageous antiviral agent, then some earlier results of ClO2 gas application against viruses will be reviewed. Finally, we hypothesize on methods to control the spread of viral infections using aqueous ClO2 solutions.


Assuntos
Betacoronavirus , Compostos Clorados/farmacologia , Doenças Transmissíveis Emergentes , Infecções por Coronavirus , Transmissão de Doença Infecciosa/prevenção & controle , Óxidos/farmacologia , Pandemias , Pneumonia Viral , Antivirais/farmacologia , Betacoronavirus/efeitos dos fármacos , Betacoronavirus/patogenicidade , Betacoronavirus/fisiologia , Protocolos Clínicos , Doenças Transmissíveis Emergentes/prevenção & controle , Doenças Transmissíveis Emergentes/virologia , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/prevenção & controle , Infecções por Coronavirus/transmissão , Infecções por Coronavirus/virologia , Desinfetantes/farmacologia , Humanos , Pandemias/prevenção & controle , Soluções Farmacêuticas/farmacologia , Pneumonia Viral/epidemiologia , Pneumonia Viral/prevenção & controle , Pneumonia Viral/transmissão , Pneumonia Viral/virologia , Projetos de Pesquisa
8.
J Food Prot ; 83(3): 412-417, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32050031

RESUMO

ABSTRACT: Fresh produce, such as blueberries, continues to be a source of foodborne illness in the United States. Despite new practices and intervention technologies, blueberries and other produce are contaminated with foodborne pathogens, such as Salmonella. The aim of this study was to evaluate the efficacy of chlorine dioxide gas (CDG) against Salmonella enterica serovars Newport, Stanley, Muenchen, and Anatum on artificially contaminated whole fresh blueberries. Blueberries were dip inoculated into a 400-mL bath containing a Salmonella serovar cocktail of either ca. 6 or 9 log CFU/mL. Samples were dried for either 2 or 24 h before treatment with 1.5 or 3 mg of CDG/L of air to a final treatment of 3.55 to 6 ppm/h/g of blueberry. Salmonella cells were recovered by stomaching CDG-treated and nontreated control samples with 0.1% peptone and enumerated on xylose lysine Tergitol 4 agar. CDG treatments achieved up to a 5.63-log CFU/g reduction of the cocktail using 5.5 ppm/h/g, whereas the lowest treatment, 4 ppm/h/g (1.5 mg of CDG/L), was still capable of a 4.45-log CFU/g reduction. Incubation time significantly (P < 0.001) affected CDG efficacy against both inoculation concentrations. Additionally, all serovars responded similarly to CDG treatment when tested individually (P > 0.0691). Finally, the availability of a water reservoir during treatments did not have a significant effect (P = 0.9818) on CDG efficacy in this study. Our results demonstrate that CDG can be an efficacious treatment option for whole blueberry decontamination.


Assuntos
Mirtilos Azuis (Planta)/microbiologia , Compostos Clorados/farmacologia , Desinfetantes , Óxidos/farmacologia , Salmonella enterica/efeitos dos fármacos , Cloro , Contagem de Colônia Microbiana , Desinfetantes/farmacologia , Microbiologia de Alimentos , Sorogrupo
9.
Environ Sci Pollut Res Int ; 27(11): 12704-12716, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32008194

RESUMO

Surface disinfection of water facilities such as water wells requires measures that can remove pathogens from the walls to ensure a high drinking water quality, but many of these measures might increase corrosion of the contact surfaces (often highly pure steel) and affect the environment negatively due to disinfectant-contaminated waste sludge and wastewater. Today, most treatments worldwide are based on hypochlorites. We investigated the extent of corrosion during treatments of steel at relevant conditions of ozone, sodium, and calcium hypochlorite for drinking water preparation, utilizing weight loss, electrochemical, solution analytical, and surface analytical methods. The ozone treatment caused significantly less corrosion as compared with sodium or calcium hypochlorite with 150-250 mg/L active chlorine. Hypochlorite or other chlorine-containing compounds were trapped in corrosion products after the surface disinfection treatment with hypochlorite, and this risked influencing subsequent corrosion after the surface disinfection treatment. A life cycle impact assessment suggested ozone treatment to have the lowest negative effects on human health, ecosystems, and resources. Calcium hypochlorite showed the highest negative environmental impact due to its production phase. Our study suggests that ozone surface disinfection treatments are preferable as compared with hypochlorite treatments from corrosion, economic, and environmental perspectives.


Assuntos
Compostos Clorados , Desinfetantes , Água Potável , Purificação da Água , Corrosão , Desinfecção , Ecossistema , Humanos , Hipoclorito de Sódio
10.
Chemosphere ; 243: 125453, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31995893

RESUMO

Fungal contamination in drinking water has been becoming a hot topic. The routine enumeration method of fungal spores is heterotrophic plate counts (HPC). However, this method is time-consuming and labor-intensive and there is also the difficulty of enumerating viable but non-culturable cells. In this study, a rapid, simple and accurate method for quantifying fungal spores and discriminating their viability in water was established using flow cytometry (FCM) combined with fluorescence dyes. The optimal staining conditions are as follows: spores suspensions are sonicated at 495 W for 5 min as pretreatment, and then 10 µL of SYBR Green I (100×) and 30 mM Ethylene diamine tetraacetic acid are added to a 500 µL water sample, which incubate at 35 °C for 20 min in dark. The concentration of fungal spores measured by FCM was highly correlated with HPC results and microscope observations, with correlation coefficient of 0.996 and 0.988, respectively. This staining method can be widely applied to the enumeration and viability evaluation of fungal spores. In addition, chlorine-based inactivation of three genera of fungal spores was assessed by plating and FCM. The result showed that all three genera of fungal spores lost culturability firstly and then membrane integrity decreased, preliminarily revealing the inactivation mechanism. The inactivation rate constants of membrane damage varied in the following order: chlorine dioxide > chlorine > chloramine. This study concluded that FCM is an appropriate and alternative tool to detect fungal spores' viability and can be used for evaluating the fungal inactivation by disinfectants.


Assuntos
Desinfecção/métodos , Citometria de Fluxo/métodos , Esporos Fúngicos/crescimento & desenvolvimento , Cloraminas/farmacologia , Cloro/farmacologia , Compostos Clorados/farmacologia , Desinfetantes/farmacologia , Corantes Fluorescentes , Fungos/citologia , Fungos/efeitos dos fármacos , Compostos Orgânicos , Óxidos/farmacologia , Esporos Fúngicos/citologia , Coloração e Rotulagem/métodos
11.
Food Microbiol ; 87: 103355, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31948612

RESUMO

Enteric pathogens such as Shiga-toxin producing Escherichia coli (STEC) and Salmonella spp. continue to be a major food safety concern for the beef industry. Currently, no single method is completely effective in controlling these pathogens during carcass processing. Previous research, however, suggested that STEC might become more susceptible to oxidative damage when exposed to carcass chilling (King et al., 2016). We aimed to test that hypothesis by evaluating the antimicrobial effects of an oxidant (chlorine dioxide, ClO2 or peroxyacetic acid, PAA) on beef meat during a simulated spray chilling process (sprayed for 4 s every 15 min for 36 cycles) and/or when applied (sprayed for 144 s) prior to spray chilling with water. In all experiments, the inactivating effects of oxidants were greatest on fat surfaces and much less effective on lean surfaces. ClO2 at 15 ppm, a non-lethal level for E. coli under optimal growth conditions, caused higher log reductions in E. coli numbers (approximately 3-log reduction) when applied during spray chilling than when applied immediately prior to 'normal' spray chilling (approximately 1-log reduction). This confirms the hypothesis that E. coli are more susceptible to oxidative stress during spray chilling. In subsequent studies, both ClO2 and PAA at lethal levels (at ≥20 and ≥ 200 ppm, respectively) applied during spray chilling resulted in pronounced inactivation of both E. coli and Salmonella enterica strains, achieving a ≥4-log reduction at the end of chilling. These results indicate that an oxidant-based application during spray chilling as an antimicrobial intervention could be effective to minimise the problems associated with enteric pathogen contamination on beef meat.


Assuntos
Antibacterianos/farmacologia , Compostos Clorados/farmacologia , Conservação de Alimentos/métodos , Óxidos/farmacologia , Ácido Peracético/farmacologia , Carne Vermelha/microbiologia , Animais , Bovinos , Conservação de Alimentos/instrumentação , Conservantes de Alimentos/farmacologia , Carne Vermelha/análise , Salmonella enterica/efeitos dos fármacos , Salmonella enterica/crescimento & desenvolvimento , Escherichia coli Shiga Toxigênica/efeitos dos fármacos , Escherichia coli Shiga Toxigênica/crescimento & desenvolvimento
12.
Artigo em Inglês | MEDLINE | ID: mdl-31724470

RESUMO

Combined sewer overflow (CSO) water introduces pathogens to receiving waters. To control pathogenic releases, chlorine may be added to disinfect CSO water. The added chlorine may react with water constituents to form oxidative species known as chlorine-produced oxidants (CPO). CPO are the sum of free and combined oxidative species that form upon adding free chlorine-bearing compounds (e.g. gaseous chlorine or hypochlorite) to water. CPO discharge is often regulated by governing agencies. Current methods to model CPO behavior do not account for CPO decay and dilution simultaneously in receiving water. This study creates a novel model for CPO demand and dilution in receiving water from chlorinated effluent in order to determine site-specific practices for implementation of a CSO water disinfection regime. To do this, representative receiving water was collected and dosed with 1, 2, and 4 mg/L chlorine. The residual chlorine was measured at intervals up to 30 min after dosing. The immediate and subsequent chlorine demand was calculated, with the subsequent demand modeled by simultaneous application of dilution and decay using pseudo-first-order decay kinetics. A comparison of model calculations indicates that application of dilution before decay underestimates CPO demand, while application of decay before dilution overestimates CPO demand.


Assuntos
Cloro/química , Desinfetantes/química , Desinfecção/métodos , Oxidantes/química , Esgotos/química , Compostos Clorados/química , Modelos Químicos , Purificação da Água
13.
Environ Geochem Health ; 42(3): 849-861, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31093815

RESUMO

Eutrophication has become great concern in recent years due to the fact that rivers, lakes, and reservoirs are the main drinking water source. Studies have been performed to enhance the removal of algae with ClO2 pre-oxidation, but there was high potential in the formation of chlorite and chlorate. In this study, ultra-sonication was employed to assist algae removal and control disinfection by-products formation in ClO2 pre-oxidation processes. It was found that solo ultra-sonication for 10 min (algae removal 86.11 ± 2.16%) could achieve similar algae removal efficiency as that with solo ClO2 (0.5 mg/L) pre-oxidation for 10 min (algae removal 87.10 ± 3.50%). In addition, no formations of chlorite and chlorate were detected in solo ultra-sonication process. Five-minutes ultra-sonication followed by 5-min 0.5 mg/L ClO2 treatment (total treatment time 10 min; algae removal 93.55 ± 3.22%) provided a better performance on algae removal compared to the solo ClO2 (0.5 mg/L) pre-oxidation for 10 min. Moreover, chlorite was undetectable. It suggests that the utilization of ultra-sonication in ClO2 pretreatment for algae removal has highly prevented the formations of chlorite and chlorate.


Assuntos
Compostos Clorados/química , Desinfecção/métodos , Eutrofização , Óxidos/química , Sonicação/métodos , Purificação da Água/métodos , Cloratos/química , Cloretos/química , Clorofórmio/química , Oxirredução , Água
14.
Environ Res ; 180: 108866, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31703977

RESUMO

In general, cartridge filters (CFs) are installed before reverse osmosis systems as a safeguard to minimize fouling of the reverse osmosis membrane in seawater desalination plants. Depending on the retention time of microorganisms and various fouling matter in the storage tank, pipe, and filter housing, serious fouling of the CF may occur, decreasing its lifetime. More importantly, biofouling of CFs in a continuous process can have a significant impact on reverse osmosis membrane fouling. Few studies related to CF fouling and control have been undertaken due to the low cost of CFs. Herein, comparative evaluation of optical density (O.D) for Cl2 and ClO2 was performed to investigate the efficiency of biofouling control and for developing alternative disinfection processes because the chemistry and reactivity of ClO2 differ from those of Cl2. The results showed that the concentrations of Cl2 and ClO2 required to achieve a log reduction value of 2 for the live bacterial cells with 180 min of contact time were 1.5 and 0.6 mg L-1, respectively. Both Cl2 and ClO2 were effective for the control of organic matter and particles. However, the required Cl2 concentration (1.5 mg L-1) was 2.5 times higher than that of ClO2 (0.6 mg L-1). Surface analysis and economic evaluation of the CF showed that ClO2 has higher biofouling control ability than Cl2 and is more economical, at a current cost of $ 23,667 during seawater desalination plant duration.


Assuntos
Incrustação Biológica , Purificação da Água , Cloro , Compostos Clorados , Membranas Artificiais , Osmose , Óxidos , Água do Mar
15.
Food Microbiol ; 86: 103308, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703866

RESUMO

The aim of this study was to use chlorine dioxide (ClO2) gas to inactivate Aspergillus flavus on green coffee beans. Green coffee beans inoculated with A. flavus were exposed to ClO2 gas generated from 0.75, 1, 1.25, or 1.5 mL of ClO2 solution in a sealed container at 25 or 50 °C (100% relative humidity [RH]) for up to 10 h. Numbers of A. flavus on beans treated at 25 °C decreased by 1.1-2.2 log cfu/bean within 1 h of exposure to ClO2 and decreased to below the detection limit (≤1.0 log cfu/bean) at all ClO2 concentrations after 10 h. At 50 °C, the microbial population reached the detection limit within 0.5 h regardless of the ClO2 solution concentration. Beans exposed to gas for 10 h at 25 °C were stored for 14 days under conditions of 43, 75, or 100% RH and 4, 12, or 25 °C. At 4 °C, visible mold growth was not established regardless of RH. After 12 days, mold was observed only at 25 °C. At 100% RH, beans stored under the same conditions without ClO2 gas treatment showed mold formation at 13 and 4 days at 12 and 25 °C, respectively.


Assuntos
Aspergillus flavus/efeitos dos fármacos , Compostos Clorados/farmacologia , Cloro/farmacologia , Coffea/microbiologia , Conservação de Alimentos/métodos , Óxidos/farmacologia , Aspergillus flavus/crescimento & desenvolvimento , Compostos Clorados/química , Contagem de Colônia Microbiana , Óxidos/química , Sementes/microbiologia
16.
Artigo em Inglês | MEDLINE | ID: mdl-31752399

RESUMO

Chlorine dioxide (ClO2) has been widely used as a disinfectant in drinking water in the past but its effects on water pipes have not been investigated deeply, mainly due to the difficult experimental set-up required to simulate real-life water pipe conditions. In the present paper, four different kinds of water pipes, two based on plastics, namely random polypropylene (PPR) and polyethylene of raised temperature (PERT/aluminum multilayer), and two made of metals, i.e., copper and galvanized steel, were put in a semi-closed system where ClO2 was dosed continuously. The semi-closed system allowed for the simulation of real ClO2 concentrations in common water distribution systems and to simulate the presence of pipes made with different materials from the source of water to the tap. Results show that ClO2 has a deep effect on all the materials tested (plastics and metals) and that severe damage occurs due to its strong oxidizing power in terms of surface chemical modification of metals and progressive cracking of plastics. These phenomena could in turn become an issue for the health and safety of drinking water due to progressive leakage of degraded products in the water.


Assuntos
Compostos Clorados/química , Cloro/química , Desinfetantes/química , Metais/química , Óxidos/química , Plásticos/química , Abastecimento de Água
17.
Artigo em Inglês | MEDLINE | ID: mdl-31752418

RESUMO

Disinfection and sterilization are needed for guaranteeing that medical and surgical instruments do not spread contagious microorganisms to patients. The aim of this study was to evaluate the efficacy of a simple manual technique of high-level disinfection (HLD) of flexible fiberoptic nasofibroscopes (FFNs) with wipes impregnated with a chlorine dioxide solution (Tristel Trio Wipes System-TTW) against a conventional automated washer machine (Soluscope ENT, Cimrex 12-AW). FFNs used in 62 patients undergoing endoscopy at an ENT clinic were sampled according to an aseptic procedure. For each nasoendoscopy, microbiological samples were taken at two times: (1) after a patient's nasoendoscopy and (2) immediately after high-level disinfection. Ten microliters of each prepared sample were inoculated onto specific culture media for the detection of nasopharyngeal flora microorganisms. The microbiological results obtained from 62 post-disinfection samples revealed bacterial growth on two FFNs disinfected with AW, and five FFNs disinfected with TTW, but this difference is not statistically significant. None of the isolates were pathogenic bacteria. Our results are different than the results obtained by two previously published studies on the TTW system. In both studies, sampling was carried out by swabbing the tip and the handle surface of FFNs. This sampling method was the least effective method means of detecting bacteria on a surface. It can be concluded that the two disinfection systems allow providers to obtain a reduction of the saprophytic and pathogenic microbial load.


Assuntos
Bactérias/isolamento & purificação , Compostos Clorados/farmacologia , Desinfetantes/farmacologia , Desinfecção/métodos , Endoscópios/microbiologia , Contaminação de Equipamentos/prevenção & controle , Óxidos/farmacologia , Humanos , Manejo de Espécimes
18.
Lett Appl Microbiol ; 69(4): 252-257, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31429475

RESUMO

Alfalfa sprouts have been implicated in multiple foodborne disease outbreaks. This study evaluated the growth of Listeria monocytogenes during sprouting of alfalfa seeds and the effectiveness of daily chlorine dioxide & ozone rinsing in controlling the growth. Alfalfa seeds inoculated with L. monocytogenes were sprouted for 5 days (25°C) with a daily aqueous ClO2 (3 ppm, 10 min) or ozone water (2 ppm, 5 min) rinse. Neither treatment significantly reduced the growth of L. monocytogenes on sprouting alfalfa seeds. The initial level of L. monocytogenes was 3·44 ± 0·27, which increased to c. 7·0 log CFU per g following 3 days of sprouting. There was no significant difference in the bacterial population between the treatment schemes. Bacterial distribution in roots (7·63 ± 0·511 log CFU per g), stems (7·51 ± 0·511 log CFU per g) and leaves (7·41 ± 0·511 log CFU per g) were similar after 5 days. Spent sanitizers had significantly lower levels of bacterial populations compared to the spent distilled water control. The results indicated that sprouting process provides a favourable condition for the growth of L. monocytogenes and the sanitizer treatment alone may not be able to reduce food safety risks. SIGNIFICANCE AND IMPACT OF THE STUDY: Sprouts are high-risk foods. Consumption of raw sprouts is frequently associated with foodborne disease outbreaks. Optimum sprouting procedure involves soaking seeds in water followed by daily water rinsing to maintain a moist environment that is also favourable for the growth of pathogenic micro-organisms. The present study emphasized the potential food safety risks during sprouting and the effect of applying daily sanitizer rinsing in the place of water rinsing to reduce those risks. The finding of this study may be useful in the development of pre-harvest and post-harvest risk management strategies.


Assuntos
Compostos Clorados/farmacologia , Doenças Transmitidas por Alimentos/prevenção & controle , Listeria monocytogenes/crescimento & desenvolvimento , Medicago sativa/microbiologia , Óxidos/farmacologia , Água/farmacologia , Contagem de Colônia Microbiana , Microbiologia de Alimentos/métodos , Inocuidade dos Alimentos/métodos , Ozônio/farmacologia , Raízes de Plantas/microbiologia , Sementes/microbiologia , Verduras/microbiologia , Água/química
19.
Molecules ; 24(17)2019 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-31450724

RESUMO

The highly prescribed antidepressant, citalopram, as one of newly emerging pollutants, has been frequently detected in the aquatic environment. Citalopram oxidation was examined during sodium hypochlorite (NaOCl) and chlorine dioxide (ClO2) chlorination processes since conventional wastewater treatment plants cannot remove citalopram effectively. Citalopram has been demonstrated to form N-nitrosodimethylamine (NDMA) during chlorination in our previous study. Further investigation on NDMA formation kinetics was conducted in the present study. Influences of operational variables (disinfectant dose, pH value) and water matrix on citalopram degradation, as well as NDMA generation, were evaluated. The results indicated high reactivity of citalopram with NaOCl and ClO2. NDMA formation included two stages during CIT oxidation, which were linear related with reaction time. NaOCl was more beneficial to remove CIT, but it caused more NDMA formation. Increasing disinfectant dosage promoted citalopram removal and NDMA formation. However, no consistent correlation was found between citalopram removal and pH. Contrary to the situation of citalopram removal, NDMA generation was enhanced when citalopram was present in actual water matrices, especially in secondary effluent. DMA, as an intermediate of citalopram chlorination, contributed to NDMA formation, but not the only way.


Assuntos
Compostos Clorados/química , Citalopram/química , Oxirredução , Óxidos/química , Hipoclorito de Sódio/química , Dimetilnitrosamina/química , Desinfetantes/farmacologia , Halogenação , Concentração de Íons de Hidrogênio , Cinética , Estrutura Molecular , Oxirredução/efeitos dos fármacos , Água/química
20.
Environ Sci Pollut Res Int ; 26(27): 28270-28283, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31368066

RESUMO

The degradation of priority substances (Directive 2013/39/UE and Watch List) by chlorine dioxide (ClO2) and the formation of disinfection by-products (DBPs) in a drinking water treatment plant (DWTP) located near Barcelona (NE Spain) were investigated. For the first time, the reactivity with ClO2 of several compounds frequently found at the entrance of the DWTP such as erythromycin, clarithromycin, chlorpyrifos, and imidacloprid was evaluated in both simulated and real conditions. To identify potential DBPs, experiments were performed at laboratory scale by simulating the operational disinfection conditions in the DWTP. Liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) working in full scan and target-MS/HRMS modes was used for the identification of the generated DBPs. Several new DBPs were found, three from erythromycin, one from clarithromycin, two from chlorpyrifos, and one from imidacloprid. Then, the presence and behavior through DWTP treatment of priority substances and their DBPs were investigated in order to evaluate their generation in real working conditions. Two of the potential DBPs, anhydroerythromycin, and N-desmethyl clarithromycin were already identified in the raw water of DWTP, but N-desmethyl clarithromycin was also generated after the chlorine dioxide treatment step. Both compounds were eliminated by the treatments applied in the DWTP; anhydroerythromycin was eliminated after ozonation in the upgraded conventional treatment and after reverse osmosis in the advanced treatment while N-desmethyl clarithromycin is recalcitrant in the upgraded conventional treatment, but it was eliminated by reverse osmosis.


Assuntos
Desinfetantes/análise , Desinfecção/métodos , Água Potável/química , Purificação da Água/métodos , Compostos Clorados , Desinfetantes/química , Filtração , Óxidos , Espanha
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA