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OBJECTIVE: The effects of sanitation and hygiene interventions on the gut microbiome and enteric pathogen burden are not well understood. We measured the association between free chlorine residue (FCR) levels in drinking water, microbiome composition, and stool enteric pathogens in infants and young children in Haiti. METHODS: FCR levels were measured in household drinking water and enteric pathogen burden was evaluated using multiplex RT-PCR of stool among 131 children from one month to five years of age living in Mirebalais, Haiti. Microbiome profiling was performed using metagenomic sequencing. RESULTS: Most individuals lived in households with undetectable FCR measured in the drinking water (112/131, 86%). Detection of enteric pathogen DNA in stool was common and did not correlate with household water FCR. The infant microbiome in households with detectable FCR demonstrated reduced richness (fewer total number of species, P = 0.04 Kruskall-Wallis test) and less diversity by Inverse Simpson measures (P = 0.05) than households with undetectable FCR. Infants in households with a detectable FCR were more likely to have abundant Bifidobacterium. Using in vitro susceptibility testing, we found that some Bifidobacterium species were resistant to chlorine. CONCLUSIONS: FCR in household drinking water did not correlate with enteric pathogen burden in our study.

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Tomato plants are a crop of great economic importance worldwide. Mexico is considered the world's leading exporter of this vegetable, with a 24% market share. However, this crop can be affected by diseases such as bacterial freckle and bacterial cancer that can be introduced to plantations through infected seeds. Pesticides are used in agriculture for disease control and are considered a source of environmental pollution. Alternatives to the use of pesticides must therefore be sought. To this effect, electrolyzed water is a technology that has been shown to have antimicrobial activity. In this study, the antimicrobial activity of electrolyzed water on Pseudomonas syringaepv. tomato and Clavibactermichiganensis subsp.michiganensis was evaluated on cells suspension and tomato seed germination. Electrolyzed oxidizing water (EOW) and electrolyzed reduced water (ERW) treatments were applied for 1, 3 and 6 minutes. In addition, seeds were infected with each of the bacterial strains separately and electrolyzed water treatments were applied. Results show that oxidizing water is more efficient as an antimicrobial agent, as it achieved 100% growth reduction of the two bacterial strains after one minute of treatment. These treatments did not affect germination percentage, since germination percentages above 90% were obtained in all treatments and the seedlings were not affected in any of the evaluated variables.

O tomate é uma colheita de grande importância econômica em todo o mundo. O México é considerado o primeiro exportador desta hortaliça no mundo, com 24% de participação. No entanto, esta cultura pode ser afetada por doenças como a mancha bacteriana e o cancro bacteriano que podem ser introduzidos nas colheitas através de sementes infectadas. Os agrotóxicos são utilizados na agricultura para controlar doenças e são considerados uma fonte de contaminação ambiental. Por esse motivo, é necessário buscar alternativas ao uso de agrotóxicos. Nesse sentido, a água eletrolisada é uma tecnologia que tem demonstrado atividade antimicrobiana. No presente estudo, a atividade antimicrobiana da água eletrolisada sobre Pseudomonas syringae pv. tomate e Clavibacter michiganensis subsp. michiganensis emcélulasem suspensão e na germinação de sementes de tomate. Os tratamentos com água eletrolisada oxidante e redutora foram aplicados por 1, 3 e 6 minutos. Por outro lado, as sementes foram infectadas com cada uma das cepas bacterianas de forma independente e foram aplicados tratamentos com água eletrolisada. Os resultados mostram que a água oxidante é mais eficiente como agente antimicrobiano, pois conseguiu uma redução de 100% no crescimento das duas cepas bacterianas após um minuto de tratamento. Os tratamentos não afetaram a porcentagem de germinação, pois em todos os tratamentos obtiveram-se porcentagens de germinação acima de 90% e as plântulas não foram afetadas em nenhuma das variáveis estudadas.

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Contamination of natural water (NW) by emerging contaminants has been widely pointed out as one of the main challenges to ensure high-quality drinking water. Thus, the effectiveness of a solar-driven free chlorine advanced oxidation process simultaneously investigating the elimination of six organic microcontaminants (OMCs) and three bacteria from NW at a pilot-scale was evaluated in this study. Firstly, the solar/free chlorine process was studied at lab-scale using a solar simulator to evaluate the effect of free chlorine concentration (0.5-10 mg L-1) on OMC degradation and generation of toxic oxyanions (e.g., ClO3- ions). Thus, the best free chlorine concentration observed was applied for the simultaneous removal of OMCs and pathogens under natural solar light at pilot scale. At lab-scale, the solar/free chlorine (2.5 mg L-1) process achieved 80% of total degradation in 5 min (1.4 kJ L-1 of accumulative UV energy) with an oxidant consumption of 0.3 mg L-1 and without ClO3- generation. Similar results were attained under natural solar irradiation at a pilot-scale. For all bacteria strains, the legally required detection limit (DL = 1 CFU 100 mL-1) for reclaimed water reuse was attained in a short contact time. Still, more importantly, the solar/free chlorine (2.5 mg L-1) process effectively avoided the possible bacterial regrowth in the post-treated sample after six days. Finally, the combination of free chlorine with solar irradiation provided a simple and energy-efficient process for OMC and bacteria removal in NW at a pilot-scale.

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A new portable and simple 3D printed device was designed for free chlorine determination in water samples. The analytical method was based on the quenching caused by free chlorine on the fluorescence emission of the carbon dots (CD) synthesized from citric acid and urea. The fluorescence was captured through the camera of a smartphone, which was coupled to the 3D printed device, and the images were processed using the RGB system by the ImageJ 1.51q software. The proposed method was selective and precise (RSD% 4.6, for n = 6), and the trueness of the results was evaluated by comparing the results obtained with those recovered by the spectrophotometric method 4500-Cl G (standard method), with good agreement between them. Moreover, the remarkable correlation between the CD signal and the free chlorine concentration resulted in a determination with low detection limits (limit of detection of 6 µg L-1 and limit of quantification of 20 µg L-1). Therefore, the new method and the related portable device could be considered a fast, economical and reliable alternative for the on-site determination of free chlorine in water samples.

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The aim of the present study was to investigate the electrochemical formation of free chlorine species (HOCl/ClO-) and their subsequent use for the degradation of the pesticide atrazine. Initially, the process of electrochemical-free chlorine production was investigated using a bench-scale electrochemical flow-cell. The most significant variables (electrolyte concentration ([NaCl]) and inter-electrode gap) of the process were obtained using a 23 factorial design and the optimum process conditions (1.73 mol L-1 and 0.56 cm) were determined by a central composite design. Following optimization of free chlorine production, three degradation techniques were investigated, individually and in combination, for atrazine degradation: electrochemical, photochemical and sonochemical. The method using the techniques in combination was denominated sono-photo-assisted electrochemical degradation. Constant current assays were performed and the sono-photo-assisted electrochemical process promoted more efficient removal of atrazine, achieving total organic carbon removal of ∼98% and removal of atrazine to levels below the detection limit (>99%) in under 30 min of treatment. Furthermore, the combination of three techniques displayed lower energy consumption, and phytotoxicity tests (Lactuca sativa) showed that there was no increase in toxicity.

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INTRODUCCIÓN: en Cuba se han desarrollado las primeras tabletas efervescentes de 3,5 mg dicloroisocianurato de sodio, como ingrediente activo no terapéutico, el cual libera una determinada cantidad de cloro al disolverse en un litro de agua, capaz de inducir a una adecuada desinfección del agua potable y lista para ingerir después de transcurrido 30 min. OBJETIVO: desarrollar y validar un método analítico yodométrico, aplicable al control de la calidad de las tabletas efervescentes de 3,5 mg de dicloroisocianurato de sodio. MÉTODOS: para la cuantificación del contenido de cloro activo libre en las tabletas efervescentes, se empleó como técnica un método potenciométrico, utilizando electrodos de platino y solución valorada de tiosulfato de sodio 0,1 N. El método desarrollado fue validado según los parámetros exigidos para la categoría I, que incluye las técnicas destinadas a cuantificar principios activos en las formas terminadas. Adicionalmente se realizaron otras pruebas para evaluar la influencia del analista y el día en los resultados analíticos. RESULTADOS: los parámetros evaluados en la validación del método se encontraron dentro de los límites establecidos. El método resultó ser específico, lineal, exacto y preciso en el rango de concentraciones estudiadas. CONCLUSIONES: los resultados permiten que el método pueda emplearse de manera confiable y segura(AU)

INTRODUCTION: Cuba has developed the first effervescent 3.5 mg sodium dichloroisocyanurate tablets as a non-therapeutic active principle. This ingredient releases certain amount of chlorine when dissolved into a litre of water and it can cause adequate disinfection of drinking water ready to be taken after 30 min. OBJECTIVE: developing and validating an analytical iodometric method applicable to the quality control of effervescent 3.5 mg sodium dichloroisocyanurate tablets. METHODS: quantitation of the free active chlorine content in effervescent tablets by using a potentiometric method based on the platinum electrodes and the tittered 0.1 N sodium thiosulphate solution. The developed method was validated as per the category I parameters including the techniques for quantitation of the active principles in the finished forms. Additionally, other tests were conducted to evaluate the influence of the analyst and of the day on the analytical results. RESULTS: the evaluated parameters in the validation of the method were within the set limits. The method was specific, linear, exact and precise in the range of studied concentrations. CONCLUSIONS: the results proved that this method can be used in a safe reliable way(AU)

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Ensaios de tratabilidade em bancada tendo cloreto férrico como coagulante foram conduzidos para avaliar efeitos da pré-ozonização e da inter-ozonização sobre variáveis de qualidade de águas em diversas etapas de tratamento: demanda de cloro livre (DCL), absorbância de luz ultravioleta em 254 nm (abs UV254) e concentração de matéria orgânica (MO). Para águas decantadas, a ozonização favoreceu a remoção de MO, mas não pareceu influenciar a redução da DCL, em relação aos ensaios sem ozonização. Para as águas filtradas, os ensaios com ozônio proporcionaram maiores remoções de MO e valores da relação DCL/MO do que os ensaios sem ozônio, porém estes últimos foram mais eficientes na redução da DCL. A ozonização da água bruta reduziu a concentração de MO e a abs UV254 mas não a DCL. A DCL imediata da água bruta foi estimada e pareceu não depender do tempo de contato.

Bench scale treatability tests with ferric chloride coagulation were conducted to assess effects of pre-ozonation, inter-ozonation on water quality variables of water samples in several stages of treatment: free chlorine demand (FCD), absorbance of Ultra Violet light in the 254 nm wavelength (UV254 abs) and organic matter (OM) concentration. Regarding settling, ozonation favored OM removal but did not seem to influence FCD reduction, as compared with tests without ozonation. Regarding filtration, tests with ozonation led to higher OM removals and FCD/OM ratios than tests without ozonation. However, tests without ozonation were more efficient in reducing the FCD. Raw water ozonation decreased OM and UV254 abs values but not FCD values. The immediate FCD was obtained for raw water and it did not seem to depend on contact time.

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