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1.
Chemosphere ; 242: 125268, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896175

RESUMO

This study investigated chlorinated transformation products (TPs) and their parent micropollutants, aromatic pharmaceuticals and personal care products (PPCPs) in the urban water bodies of two metropolitan cities. Nine PPCPs and 16 TPs were quantitatively or semi-quantitatively determined using isotope dilution techniques and liquid chromatography-tandem mass spectrometry. TPs and most PPCPs were effectively removed by conventional wastewater treatments in a wastewater treatment plant (WWTP). Chlorinated parabens and all PPCPs (at concentrations below 1000 ng/L) were present in the waters receiving treated wastewater. By contrast, the waters receiving untreated wastewater contained higher levels of PPCPs (up to 9400 ng/L) and more species of chlorinated TPs including chlorinated parabens, triclosan, diclofenac, and bisphenol A. The very different chemical profiles between the water bodies of the two cities of similar geographical and climatic properties may be attributed to their respective uses of chemicals and policies of wastewater management. No apparent increase in the number of species or abundances of TPs was observed in either the chlorinated wastewater or the seawater rich in halogens. This is the first study to elucidate and compare the profiles of multiple TPs and their parent PPCPs in the water bodies of coastal cities from tropical islands. Our findings suggest that chlorinated derivatives of bisphenol A, diclofenac, triclosan, and parabens in the surface water originate from sources other than wastewater disinfection or marine chlorination. Although further studies are needed to identify the origins, conventional wastewater treatments may protect natural water bodies against contamination by those chlorinated substances.


Assuntos
Desinfecção/métodos , Monitoramento Ambiental/métodos , Água do Mar/química , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Cromatografia Líquida , Cidades , Cosméticos/análise , Halogenação , Preparações Farmacêuticas/análise , Taiwan
2.
Chemosphere ; 242: 125310, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896192

RESUMO

The bacterial composition of biofilms in drinking water distribution systems is significantly impacted by the disinfection regime and substrate material. However, studies that have addressed the changes in the biofilm community during the early stage of formation (less than 10 weeks) were not yet adequate. Here, we explore the effects of the substrate materials (cast iron, stainless steel, copper, polyvinyl chloride, and high density polyethylene) and different disinfectants (chlorine and chloramine) on the community composition and function of young biofilm by using 16S rDNA sequencing. The results showed that Alphaproteobacteria (39.14%-80.87%) and Actinobacteria (5.90%-40.03%) were the dominant classes in chlorine-disinfection samples, while Alphaproteobacteria (17.46%-74.18%) and Betaproteobacteria (3.79%-68.50%) became dominant in a chloraminated group. The infrequently discussed genus Phreatobacter became predominant in the chlorinated samples, but it was inhibited by chloramine and copper ions. The key driver of the community composition was indicated as different disinfectants according to principle coordination analysis (PCoA) and Permutational multivariate analysis of variance (Adonis test), and the bacterial community changed significantly over time. Communities of biofilms grown on cast iron showed a great distance from the other materials according to Bray-Curtis dissimilarity, and they had a unique dominant genus, Dechloromonas. A metagenomics prediction based on 16S rDNA was used to detect the functional pathways of antibiotic biosynthesis and beta-lactam resistance, and it revealed that several pathways were significantly different in terms of their chlorinated and chloraminated groups.


Assuntos
Biofilmes/efeitos dos fármacos , Cloraminas/farmacologia , Cloro/farmacologia , Desinfetantes/farmacologia , Água Potável/microbiologia , Microbiota/efeitos dos fármacos , Materiais de Construção/microbiologia , Desinfecção/métodos , Água Potável/química , Ferro , Microbiota/genética , RNA Ribossômico 16S/genética , Aço Inoxidável , Microbiologia da Água/normas
3.
Br J Nurs ; 29(2): S24-S26, 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31972108

RESUMO

PURPOSE: Preventing CLABSI events in the dialysis inpatient population represents significant challenges. Bacteremia associated with lines or grafts are common health-associated infections that lead to adverse patient outcomes. Dialysis patients represent a much higher infection risk due to health frequency needs, more frequent hospitalizations, multiple comorbidity issues, fistula functionality, and multiple attempts for line access leading to additional complications, costs, morbidity, and mortality. METHODS: An observational study was conducted including central line device days, CLABSI events, and possible confounding variables in admitted dialysis patients. All CLABSI data were identified according to the Centers for Disease Control and Prevention's National Healthcare Safety Network's definitions for CLABSIs. The intervention involved the removal of 70% alcohol swabs and alcohol hub disinfecting caps, then replacing with swabs containing 3.15% chlorhexidine gluconate/70% alcohol for central line hub disinfection and vascular graft access skin disinfection. RESULTS: The 5-year preintervention period (2008-2012) involved 7568 central line days, 11 CLABSI events, and a 1.45 per 1000 device day rate. The 6-month trial period involved 1559 central line days and no CLABSI events. The 5-year postimplementation period (2013-2017) involved 9787 central line days, 5 CLABSI events, and a 0.51 per 1000 device day rate. The postimplementation period represented a statistically significant (P value=0.0493) reduction with 65% fewer CLABSI events compared with the preimplementation period. LIMITATIONS: A limitation was variations in scrub time and dry time during central venous catheter hub access. While we were comparing 2 products, behavioral practices using these 2 products were possible influencers and represent a possible confounding variable. CONCLUSIONS: This study found that using alcohol with chlorhexidine gluconate prior to accessing central line hubs and vascular grafts allows for reduction in CLABSI events and sustains statistically significant lower CLABSI rates in the inpatient dialysis population. HIGHLIGHTS Using alcohol with chlorhexidine gluconate (CHG) before accessing central line hubs helps reduce central line-associated bloodstream infection (CLABSI) events Using alcohol with CHG before accessing vascular grafts helps reduce CLABSI events A statistically significant reduction (65%) in CLABSI events occurred after use. Statistically significant lower CLABSI rates are sustainable with use of alcohol with CHG.


Assuntos
Bacteriemia/prevenção & controle , Infecções Relacionadas a Cateter/prevenção & controle , Infecção Hospitalar/prevenção & controle , Desinfecção/métodos , Diálise Renal/enfermagem , Álcoois/administração & dosagem , Cateterismo Venoso Central/efeitos adversos , Clorexidina/administração & dosagem , Clorexidina/análogos & derivados , Humanos , Pesquisa em Avaliação de Enfermagem
4.
J Photochem Photobiol B ; 202: 111699, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31756585

RESUMO

In this work, we propose a novel application of ERIC-PCR technique to study DNA damage after ultraviolet radiation (UV) and peracetic acid (PAA) treatment for water disinfection purpose. The efficacy of both treatments on E. coli suspension was evaluated by two approaches: through monitoring of inactivation by conventional culture technique, and by analyzing DNA damage with ERIC-PCR. All the experiments were carried out in a batch reactor, using three intensities of UV-C radiation (10.5, 4.2 and 2.1 mW/cm2) and different PAA concentrations (4 to 16 ppm). Both treatments produced bacterial inactivation in a dose-response fashion. Based on the results of bacterial count we obtained an index of inactivation (INACI). For each sample, DNA extraction was performed and evaluated by ERIC-PCR. Qualitative modifications were observed in ERIC-PCR band patterns for all the UV-C radiation intensities used, but no changes were detected at any of the PAA concentrations. The banding pattern modifications observed are consequence of the interruption of Taq polymerase enzyme amplification-activity, caused by the presence of alterations on the DNA structure (dimer and hydrates formation). Furthermore, an index was proposed to measure DNA damage (DNADI) regarding the changes in the relative optical density values of the amplification products. A linear correlation was obtained with a high correspondence between the inactivation index (INACI) and the DNA damage index (DNADI), that was expressed as DNADI = 0.05881×INACI. This approach proves that ERIC-PCR is a feasible and valuable tool for detecting and quantifying DNA damage and it may provide a useful strategy for bacterial identification, tracking changes in DNA and providing reliable and reproducible data.


Assuntos
Dano ao DNA , Enterobacteriaceae/genética , Purificação da Água/métodos , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/efeitos da radiação , DNA Bacteriano/química , DNA Bacteriano/metabolismo , Desinfecção/métodos , Ácido Peracético/farmacologia , Reação em Cadeia da Polimerase , Raios Ultravioleta
5.
Chemosphere ; 240: 124941, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726615

RESUMO

Ametryn (AMT), one of the most widely used herbicides in agriculture, has been frequently detected as a micropollutant in many aquatic environments. AMT residue not only pollutes water but also acts as a precursor for the production of disinfection by-products (DBPs). This study systematically investigated the fate of AMT during the UV/chlorine process. It was observed that the combination of UV irradiation and chlorination degraded AMT synergistically. The results of the radical quenching experiments suggested that AMT degradation by the UV/chlorine process involved the participation of UV photolysis, hydroxyl radical (OH) reactions, and reactive chlorine species (RCS) reactions, which accounted for 45.4%, 36.4%, and 14.5% of the degradation, respectively. Moreover, we found that Cl- 2 was an important reactive radical for AMT degradation. The chlorine dose, pH, coexisting anions (Cl- and HCO3-), and natural organic matter (NOM) were found to affect AMT degradation during the UV/chlorine process. Nineteen predominant intermediates/products of AMT degradation during UV/chlorine process were identified, including atrazine. Moreover, the corresponding transformation pathways were proposed, including electron transfer, bond cleavage (C-S, C-N), radical (OH, Cl and Cl- 2) reactions, and subsequent hydroxylation. The toxicity tests with Vibrio fischeri on AMT degradation suggested that more DBPs were generated by UV/chlorine-treated AMT, which possessed higher acute toxicity than AMT did. Although the UV/chlorine process evidently promoted the AMT degradation, optimization of process parameters may reduce the DBP production and merits further investigation.


Assuntos
Herbicidas/toxicidade , Triazinas/toxicidade , Poluentes Químicos da Água/toxicidade , Purificação da Água/métodos , Aliivibrio fischeri , Cloro/química , Desinfecção/métodos , Halogenação , Radical Hidroxila/química , Cinética , Fotólise , Raios Ultravioleta , Água , Poluentes Químicos da Água/análise
6.
Huan Jing Ke Xue ; 41(1): 253-261, 2020 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854926

RESUMO

This study was carried out in the ozone (O3) and biological activated carbon (BAC) section of a drinking water plant to investigate the effects of O3 on microbial and effluent disinfection by-products (DBPs) in BAC during drinking water treatment. The water quality, dissolved organic matter (DOM) characteristics, microbial activity, and DBPs formation at different O3 concentrations were analyzed. Results showed that the effect of O3 on microorganisms is mainly that it increased the utilization efficiency of DOM. However, excessive O3 increased the amount of organic matter such as protein and microbial metabolites (SMPs) in the effluent. When the O3 concentration increased from 0 mg·L-1 to 2.0 mg·L-1, the survival rate of microorganisms in the BAC decreased from 95.10% to 62.60%. However, since O3 transforms organic matter into a biodegradable substance, we found that microbial activity increased by 62.52% and that the biofiltration of the BAC was enhanced. When the O3 concentration was further increased to 4.0 mg·L-1, the microbial survival rate decreased to 49.9% and the protein and SMPs produced by the microorganisms increased. This resulted in an increased formation of carbon-containing DBPs (C-DBPs) and nitrogen-containing DBPs (N-DBPs) by 41.93% and 7.18%, respectively. In summary, an appropriate dosage of O3 was beneficial for removing DOM by O3-BAC, but we found that an excessive O3 concentration caused the formation of new DBPs precursors.


Assuntos
Carvão Vegetal , Água Potável/microbiologia , Ozônio , Purificação da Água/métodos , Desinfecção/métodos , Poluentes Químicos da Água , Qualidade da Água
7.
Curr Opin Ophthalmol ; 31(1): 28-32, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31770164

RESUMO

PURPOSE OF REVIEW: This article reviews the various challenges in infection control in eye clinics and successful measures taken to prevent nosocomial infections. RECENT FINDINGS: The Center for Disease Control recommends hand-washing when hands are visibly soiled, and after direct contact with patients, and inanimate objects such as medical equipment. Published studies have identified poor hygiene in clinical settings as a major cause of nosocomial outbreaks, particularly in cases of epidemic keratoconjunctivitis (EKC). Some studies of EKC outbreaks are able to support direct observation of hygiene lapses with molecular analysis that can match viral strains on particular instruments to those found in infected patients. Although most studies are about adenoviral infection and tonometer use, researchers have found viral and bacterial loads on other common surfaces, indicating a need for further research. SUMMARY: Proper hygiene in eye clinics requires special attention because of the potential to examine many patients at a time and because multiple instruments are often used during a single exam. Studies reinforce the link between hygiene and outbreak prevention, and more research can be done to determine the specific links between certain instruments and nosocomial infections.


Assuntos
Infecção Hospitalar/prevenção & controle , Desinfecção/métodos , Higiene das Mãos , Controle de Infecções/métodos , Oftalmologia/instrumentação , Esterilização/métodos , Instituições de Assistência Ambulatorial/normas , Humanos , Oftalmologia/normas
8.
Chemosphere ; 238: 124583, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31425865

RESUMO

The presence of bromide (Br-) in water results in the formation of brominated disinfection byproducts (DBPs) after chlorination, which are much more cytotoxic and genotoxic than their chlorinated analogs. Given that conventional water treatment processes (e.g., coagulation, flocculation, and sedimentation) fail to remove Br- effectively, in this study, we systematically tested and compared the performance of different anion exchange resins, particularly two novel Br-selective resins, for the removal of Br-. The resins performance was evaluated under both typical and challenging background water conditions by varying the concentrations of anions and organic matter. The overall Br- removal results followed the trend of Purolite-Br ≥ MIEX-Br > IRA910 ≥ IRA900 > MIEX-Gold > MIEX-DOC. Further evaluation of Purolite-Br resin showed Br- removal efficiencies of 93.5 ±â€¯4.5% for the initial Br- concentration of 0.25 mg/L in the presence of competing anions (i.e., Cl-, NO3-, NO2-, SO42-, PO43-, and a mixture of all five), alkalinity and organic matter. In addition, experiments under challenging background water conditions confirmed the selectivity of the resins (i.e. Purolite-Br and MIEX-Br) in removing Br-, with SO42- and Cl- exhibiting the greatest influence upon the resin performance followed by NOM concentration, regardless of the NOM characteristic. After Br- removal, both the subsequent formation of brominated DBPs (trihalomethanes, haloacetic acids, and haloacetonitriles), and the total organic halogens (TOX), decreased by ∼90% under the uniform formation conditions. Overall, Br-selective resins represent a promising alternative for the efficient control of Br-DBPs in water treatment plants.


Assuntos
Resinas de Troca de Ânions/química , Brometos/análise , Trialometanos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Desinfecção/métodos , Floculação , Halogenação , Troca Iônica
9.
Food Microbiol ; 85: 103307, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31500711

RESUMO

Cold atmospheric-gaseous plasma (CAP) is an emerging non-thermal technology for decontamination of foodborne bacterial and viral pathogens. We obtained a >5 log10 reduction in the titer (TCID50) of feline calicivirus (FCV) on stainless steel discs and Romaine lettuce leaves after 3 min wet exposure to air plasma generated by a two-dimensional array of integrated coaxial-microhollow dielectric barrier discharge (2D-AICM-DBD). However, when human norovirus (HuNoV GII.4) was treated for 5 min under the same conditions, ~2.6 log10 (>99.5%) reduction in genome copy number was observed as measured by ethidium monoazide-coupled RT-qPCR (EMA-RT-qPCR). To assess this discrepancy, we studied CAP's effect on FCV by the cell culture method and by the EMA-coupled RT-qPCR method. It was found that the molecular titration method (EMA-RT-qPCR) underestimates the level of virus reduction by CAP. Additionally, the fecal matter present in HuNoV samples partially suppressed virucidal activity of CAP. Assuming that the lower virus reduction measured by EMA-RT-qPCR method compared to cell culture method for FCV is the same as for HuNoV, we can conclude that FCV may be used as a surrogate for HuNoV to assess the virucidal effect of CAP. CAP is able to inactivate 3.5 Log10 units of HuNoV at low titers after 2 min of exposure.


Assuntos
Fezes/virologia , Norovirus/efeitos dos fármacos , Gases em Plasma/farmacologia , Inativação de Vírus/efeitos dos fármacos , Azidas , Calicivirus Felino/efeitos dos fármacos , Calicivirus Felino/genética , Desinfecção/métodos , Humanos , Alface/virologia , Norovirus/genética , Reação em Cadeia da Polimerase em Tempo Real , Aço Inoxidável
10.
Chemosphere ; 238: 124695, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31545215

RESUMO

As the effective adsorbents, carbon materials (CMs) are typically used in the removal of disinfection byproduct (DBP) precursors during the water treatment by adding CMs before disinfection procedure. However, after the separation of CMs from the treated water by flocculation, sedimentation, and filtration, a small amount of loaded activated carbon could be released into the water treatment system and affect the DBP formation in the following disinfection. In this study, three CMs, including coal-made activated carbon (CAC), sawdust charcoal (SCC), and hydroxylated multiwall carbon nanotubes (OH-MWCNT), were used to explore the effects of residual CMs in the formation of DBPs. The results indicated that some DBP precursors could be irreversibly adsorbed into the pore structure of CMs and hardly to be extracted and determined, then affected the DBP formation in the water system. In the chlorination process of surface water samples, CMs have similar effects on the formation of DBPs. However, given that water samples contain a variety of complex substances, the effects of residual CMs on the formation of DBPs were also slightly changed.


Assuntos
Carvão Vegetal/química , Cloro/análise , Nanotubos de Carbono/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Desinfecção/métodos , Floculação , Halogenação
11.
Chemosphere ; 239: 124790, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31521927

RESUMO

Disinfection by-products (DBPs) play a significant role in human health. Identification of the precursor of DBPs, which constitutes dissolved organic matter (DOM), can help optimize the processes in a drinking water treatment plant (DWTP). This is very important for obtaining more safe water. In this context, a one-year study was performed in a DWTP. Fluorescence spectra of DOM were quantified for determining DOM composition and properties, and the corresponding DBPs formation was analyzed. Hydrophobic neutral and acidic compounds were found to be the two predominant substances forming DBPs, which also were dominant in the DOM. Coagulation and sedimentation were not effective in DOM elimination. Besides, sand filtration caused organic compounds to increase by 14.8% on average, especially 28.59% for aromatic protein II and 18.7% for soluble microbial product-like compounds, which was due to metabolism by microorganisms present in the filter. Carbonaceous DBPs were elevated from 34.8 µg/L in source water to 42.5 µg/L in effluent, along with organic compounds increasing in filtration, and nitrogenous DBPs were under detection in winter. All DBPs appeared at a high level in summer. Accordingly, enhanced coagulation process and measures that can avoid the release of organic compounds during filtration have been suggested. As the source water was rarely affected by human activities in the study area and owing to the wide use of traditional treatment process, the data of this research can be regarded as environmental background values and the results are considered as a significant reference.


Assuntos
Desinfetantes/química , Água Potável/química , Purificação da Água/métodos , China , Desinfetantes/análise , Desinfecção/métodos , Filtração , Halogenação , Estações do Ano , Espectrometria de Fluorescência , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química
12.
J Water Health ; 17(6): 921-929, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31850899

RESUMO

Solar water disinfection (SODIS) is a process by which microbially contaminated water is disinfected by transmitting solar ultraviolet radiation to the water, rendering the bacteria inactive. The purpose of this project was to determine a residence time for disinfection in specific applications using a 3-log reduction in colony-forming units per milliliter (CFU/mL). The water was contained in quartz tubes and tested over both flat and parabolic reflectors. While UVA and UVB radiation are diffuse and independent of reflector style, water temperature is affected by solar concentration. The two reflector styles were studied to identify how insolation level and temperature affects the bacteria inactivation process. Escherichia coli, DH5α, was inoculated into sterile water and treated for 2, 4, and 8 h. The study had several conclusions, first that a 5-log reduction was achieved after 2 h, for all water temperature and insolation levels. The reflector style did not have a measurable effect on inactivation due to the short disinfection time, but the water temperature increased significantly with the parabolic reflectors. A thermal model of the two systems confirmed that the parabolic configuration resulted in higher energy input, making it the preferred configuration for disinfection with lower residence times.


Assuntos
Desinfecção/métodos , Escherichia coli/efeitos da radiação , Raios Ultravioleta , Purificação da Água/métodos , Relação Dose-Resposta à Radiação , Humanos , Luz Solar , Temperatura Ambiente , Água/química , Microbiologia da Água
13.
Pan Afr Med J ; 33: 244, 2019.
Artigo em Francês | MEDLINE | ID: mdl-31692810

RESUMO

Introduction: Access to drinking water and sanitation has been a long-standing issue between many States. However, it represents a daily struggle for hundreds of thousands of city dwellers who live mainly in the developing countries. The government of Cameroon with the assistance of providers of funds have implemented strategies to make sanitation and access to safe drinking water a reality. We have therefore decided to assess sanitation and access to drinking water in Douala V sub division. Method: We conducted a cross-sectional descriptive study from May to June 2018. We used a two-stage random sampling. Data were collected using a questionnaire. The analysis was conducted using Epi Info Version 7.1.3.3. Results: Our study shows that 22.47% of subjects discharged waters into the natural environment after use. Then, 65,55% (493/752) of households consumed borehole water; 53.69% of households rode between 1 to 5 km, 49.25% walked more than 15 minutes to collect water and 85,50% of households did not use a water treatment method. Only 14.49% of subjects used a water treatment method. No household used solar water disinfection (SODIS); 2/752 households (0.26%) had no latrine. Most of the households (54.52%; 410/752) discharged domestic wastes onto the street. Conclusion: The creation of decentralized units: the drillings, waste disposal systems and water treatment education to meet basic needs are essential.


Assuntos
Água Potável/normas , Saneamento/normas , Abastecimento de Água/normas , Camarões , Estudos Transversais , Países em Desenvolvimento , Desinfecção/métodos , Características da Família , Feminino , Humanos , Masculino , Inquéritos e Questionários , Toaletes/estatística & dados numéricos
14.
Wilderness Environ Med ; 30(4S): S100-S120, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31668519

RESUMO

To provide guidance to clinicians, the Wilderness Medical Society convened experts to develop evidence-based guidelines for water disinfection in situations where the potability of available water is not ensured, including wilderness and international travel, areas affected by disaster, and other areas without adequate sanitation. The guidelines present the available methods for reducing or eliminating microbiologic contamination of water for individuals, groups, or households; evaluation of their effectiveness; and practical considerations. The evidence evaluation includes both laboratory and clinical publications. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks or burdens, according to the criteria published by the American College of Chest Physicians.


Assuntos
Padrões de Prática Médica , Purificação da Água/métodos , Medicina Selvagem/normas , Desastres , Desinfecção/métodos , Humanos , Sociedades Médicas , Doença Relacionada a Viagens , Microbiologia da Água , Medicina Selvagem/métodos
15.
Ecotoxicol Environ Saf ; 186: 109768, 2019 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-31606645

RESUMO

The studies on occurrence of contaminants of emerging concern in drinking water treatment plants or even wastewater treatment plants in developing country like India, are very limited. Trihalomethanes (THMs) is one such contaminant of concern in drinking water treatment sector. THMs are the major disinfection byproducts (DBPs) formed during the widely used chlorination process. Their identification and removal is of utmost importance in developed as well as developing nations. This study is first of its kind to assess the removal of mixture of urban run-off driven organic matter, agricultural run-off driven organic matter, untreated sewage effluent driven organic matter and little natural organic matter (NOM) (altogether NefOM) (major DBP precursors) using advanced oxidation processes (AOPs) in the Indian region. Since, NOM vary geographically, this study will add up to applicability of generally utilized AOPs for removal of site explicit (Indian) NefOM. Trihalomethanes at a conventional water treatment plant at Mathura and a moving bed biofilm based non-conventional water treatment plant at Agra were monitored over a year, demonstrating the inability of the water treatment plants to limit formation of DBPs from Yamuna inlet water at any time of the year. Various AOPs (UV-H2O2, O3-H2O2, O3) and UV (ultraviolet) photolysis were assessed for their ability to decrease the trihalomethane forming potential (THMFP) by degrading the contaminants in the waters of Yamuna. Kinetic studies were conducted to evaluate the selected AOPs based on their ability to mineralize dissolved organic carbon (DOC), and decrease UV254 at various pH, UV intensities, and ozone and hydrogen peroxide concentrations. UV-L/H2O2 at an intensity of 47 mJ/cm2/min, pH = 7, and at hydrogen peroxide concentration of 0.5 mM provided an optimum reduction of DOC (64%) and UV254 (87%). Fractionation studies indicated that treatment by UV-L/H2O2 leads to the most significant decrease in the hydrophobic fraction of the water, while further study indicated that UV-L/H2O2 also showed maximum attenuation of THMFP.


Assuntos
Cloro/química , Desinfecção/métodos , Trialometanos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Países em Desenvolvimento , Substâncias Húmicas/análise , Peróxido de Hidrogênio/química , Índia , Cinética , Oxirredução , Ozônio/química , Fotólise , Esgotos/química , Trialometanos/efeitos da radiação , Raios Ultravioleta , Águas Residuárias/química , Poluentes Químicos da Água/efeitos da radiação
16.
Braz Oral Res ; 33(suppl 1): e072, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31576956

RESUMO

Different surgical treatment strategies for peri-implantitis with the use of graft material and membranes have been suggested without any longitudinal remarkable success rate. The present preliminary study was aimed to analyze a new clinical approach based on the disinfection of the implant connection, the disinfection of the implant surface and GBR approach in the treatment of circumferential and semi-circumferential bony defect resulting from peri-implantitis. Six consecutive patients were selected for the present study. After removal of factors that could potentially influence peri-implant pathology, the prosthetic rehabilitation was always removed and a full thickness flap was elevated to allow access to the peri-implant defect and the exposed implant surface. Once the defect was degranulated and the implant surface cleaned, a mixture (50:50) of autogenous bone and allograft was used. Guided bone regeneration technique using membranes was adopted and the flaps were closed for a submerged healing. Six months thereafter, a new re-opening procedure was performed and cleaned superstructures and crowns were repositioned. Patients were followed for one year thereafter and recalled for a customized oral hygiene every three months. Radiological and periodontal analysis was performed before surgery and every six months. The studied procedure was associated with a pronounced increase in REC and CAL with stable peri-implant conditions at 6 and 12 months. PI, BOP and PD values were significantly reduced both at 6 and 12 months. At 12 months, a mean PD gain of 4.5 mm and a bone loss reduction of 5.1 mm was obtained. Within the limitation of the present preliminary study, the proposed technique might represent a promising result for treatment of circumferential and semi-circumferential bone defects around implants affected by peri-implantitis.


Assuntos
Implantes Dentários , Desinfecção/métodos , Peri-Implantite/cirurgia , Regeneração Óssea , Prótese Ancorada no Osso , Seguimentos , Humanos , Peri-Implantite/diagnóstico por imagem , Estudos Prospectivos , Radiografia Dentária , Reprodutibilidade dos Testes , Estatísticas não Paramétricas , Propriedades de Superfície , Fatores de Tempo , Resultado do Tratamento
17.
Int J Food Microbiol ; 309: 108334, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31520893

RESUMO

In this study, we show that phosphate decreases the spore heat resistance by accelerating the rate of loss of cations from spores. Heat resistance of spores of Geobacillus stearothermophilus A1, D1, P3 and ATCC 12980 were determined in distilled water containing varying concentrations (0.1, 1 and 2% w/v) of di­sodium phosphate. The average decimal reduction times (D value) for strains A1, D1, P3 and ATCC 12980 in distilled water were 5.8, 6.8, 5.7 and 9 min at 110 °C respectively. On the addition of 0.1, 1 and 2% w/v of di­sodium phosphate, the average D110 values of all the strains in distilled water were lowered by 50, 61 and 70% respectively. Addition of 0.05% w/v of Na-EDTA to distilled water resulted in lowering of the average D110 value of all the strains by 55%. Heat resistance of spores of A1, D1, P3 and ATCC 12980 was found to be associated with the Dipicolinic Acid (DPA) content whose concentrations were 0.25, 0.30, 0.27 and 1.6 pg per spore respectively. Analysis by atomic absorption spectroscopy revealed that the phosphate present in the heating medium causes excess release of calcium from spores with 2% w/v phosphate being highly effective, thus confirming the chelating effect of phosphate. This study provides insight into the heat resistance and the increased heat sensitivity of spores of G. stearothermophilus A1, D1 and P3 in the presence of phosphate, which can be used in the design of Cleaning in Place (CIP) systems involving phosphate based cleaning agents to combat biofilms and spores in the dairy industry.


Assuntos
Desinfecção/métodos , Geobacillus stearothermophilus/crescimento & desenvolvimento , Fosfatos/farmacologia , Ácidos Picolínicos/análise , Esporos Bacterianos/efeitos dos fármacos , Indústria de Laticínios/métodos , Calefação/métodos , Temperatura Alta
18.
Chemosphere ; 235: 1041-1049, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561293

RESUMO

Magnetic carbon nanotube (MCNT) composites with titanium dioxide (TiO2) have an enhanced photocatalytic disinfection efficiency (i.e. higher disinfection rate) and better applicability (i.e. solar light applicability and catalyst separation using its magnetic property) than bare TiO2 and/or MCNT. However, the role and mechanism of MCNT in the disinfection process are still unclear. Therefore, this study aimed at investigating the disinfection mechanism of Escherichia coli using MCNT-TiO2 nanocomposites under various conditions (i.e. the presence and absence of light and reactive oxygen species scavengers, and different MCNT-TiO2 ratio) and photocatalytic disinfection models. The results showed that (i) MCNT and its nanocomposites with TiO2 had much higher disinfection efficiencies than bare TiO2, (ii) the physical bacterial capture was the dominant disinfection mechanism, (iii) the higher disinfection rate was found at an optimum MCNT:TiO2 ratio of 5:1 under the tested experimental conditions, (iv) hydroxyl radical (OH) was the influencing reactive oxygen species on the photocatalytic disinfection using MCNT-TiO2, and (v) good correlation between experimental parameters (i.e. carbon contents, surface area and concentration of MCNT-TiO2) and the contribution rate of physical and photocatalysis reactions. The finding from this study and the methods proposed herein are essential for understanding the photocatalytic disinfection processes using TiO2 and its carbonaceous nanocomposites, which can promote the application of photocatalytic disinfection process.


Assuntos
Desinfecção/métodos , Escherichia coli/efeitos dos fármacos , Nanocompostos/química , Nanotubos de Carbono , Titânio , Catálise , Magnetismo , Nanocompostos/toxicidade , Fotólise/efeitos dos fármacos
19.
Chemosphere ; 235: 1116-1124, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561302

RESUMO

The porous graphitic carbon nitride nanosheets (PCNSs) with high yields were synthesized by using one-step chemical exfoliation method. PCNSs accelerated separation efficiency of photo-generated electron-hole pairs in comparison to bulk graphitic carbon nitride. The PCNS5 (exfoliation for 5 h) exhibited optimal photocatalytic disinfection capability towards Escherichia coli K-12 under simulated solar light irradiation with complete disinfection of 6.5 log10 cfu/mL of E. coil K-12 within 2 h. The enhanced photocatalytic activity of PCNS5 originated from mesoporous nanosheet structure. The possible mechanism of photocatalytic disinfection has proposed that intracellular reactive oxygen species levels and the activities of antioxidant enzymes (e.g., catalase and superoxide dismutase) were enhanced. Transmission electron microscope images observed during photocatalytic disinfection process suggested that the cell membrane was regarded as the first target for oxidation, resulting in a faster leakage of cytoplasmic content and finally degradation of DNA leading to bacterial death. Furthermore, the trapping experiment showed that superoxide radical (•O2-) and holes (h+) were responsible for E. coli K-12 disinfection by PCNS5.


Assuntos
Desinfecção/métodos , Escherichia coli K12/efeitos dos fármacos , Nanoestruturas/química , Nitrilos/toxicidade , Fotólise , Bactérias/efeitos dos fármacos , Membrana Celular/metabolismo , Dano ao DNA , Oxirredução , Porosidade , Espécies Reativas de Oxigênio
20.
PLoS Negl Trop Dis ; 13(9): e0007777, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31536504

RESUMO

BACKGROUND: Helminthiases are a group of disabling neglected tropical diseases that affect billions of people worldwide. Current control methods use preventative chemotherapy but reinfection is common and an inter-sectoral approach is required if elimination is to be achieved. Household and community scale water treatment can be used to provide a safe alternative water supply for contact activities, reducing exposure to WASH (water, sanitation, and hygiene) -related helminths. With the introduction of ultraviolet light emitting diodes (UV-C LEDs), ultraviolet (UV) disinfection could be a realistic option for water treatment in low-income regions in the near future, to provide safe alternative water supplies for drinking and contact activities such as handwashing, bathing, and laundry, but currently there is no guidance for the use of UV or solar disinfection against helminths. METHODOLOGY: A qualitative systematic review of existing literature was carried out to establish which WASH-related helminths are more susceptible to UV disinfection and identify gaps in research to inform future studies. The search included all species that can infect humans and can be transmitted through water or wastewater. Five online databases were searched and results were categorized based on the UV source: sunlight and solar simulators, UV-A and UV-B (long wavelength) sources, and UV-C (germicidal) sources. CONCLUSIONS: There has been very little research into the UV sensitivity of helminths; only 47 studies were included in this review and the majority were carried out before the standard protocol for UV disinfection experiments was published. Only 18 species were studied; however all species could be inactivated by UV light. Fluences required to achieve a 1-log inactivation ranged from 5 mJ/cm2 to over 800 mJ/cm2. Larval forms were generally more sensitive to UV light than species which remain as an egg in the environment. This review confirms that further research is required to produce detailed recommendations for household or community scale UV-C LED or solar disinfection (SODIS) of water for preventing helminthiases.


Assuntos
Desinfecção/métodos , Helmintos/efeitos da radiação , Raios Ultravioleta , Purificação da Água/métodos , Animais , Helmintíase/prevenção & controle , Humanos , Higiene , Saneamento/métodos , Luz Solar , Água/parasitologia
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