RESUMO
Greywater reuse has emerged as a promising solution for addressing water shortages. However, greywater needs treatment before reuse to meet the required water quality standards. Conventional wastewater treatment technologies are unsuitable for recreating highly decentralized domestic greywater. This study evaluated bioelectrochemical reactors (BERs) with granular activated carbon (GAC) as a sustainable alternative for developing decentralized and low-cost biological treatment systems. BERs using GAC as the anode material and conventional GAC biofilters (BFs) for synthetic greywater treatment were operated in batch mode for 110 days in two stages: (i) with polarized anodes at -150 mV vs. Ag/AgCl and (ii) as a microbial fuel cell with an external resistance of 1 kΩ. Anode polarization produced an electrosorption effect, increasing the ion removal of the BERs. Power production during the operation and cyclic voltammetry tests of the extracted granules revealed electrochemically active biofilm development on the BERs. Although low power density (0.193 ± 0.052 µW m-3) was observed in BERs, they showed a similar performance in sCOD removal (BER = 91.6-89.6 %; BF = 96.2-93.2 %) and turbidity removal (BER = 81-82 %; BF = 30-62 %) to BFs that used 50 % aeration. Additionally, scanning electron microscopy of sampled granules showed higher biomass formation in BER granules than in BF granules, suggesting a higher contribution of sessile (vs. planktonic) cells to the treatment. Thus, the results highlight the synergistic removal effect of the GAC-based BER. The scalable design presented in this study represents a proof-of-concept for developing BERs to use in decentralized greywater treatment systems.
Assuntos
Reatores Biológicos , Carvão Vegetal , Purificação da Água , Carvão Vegetal/química , Purificação da Água/métodos , Fontes de Energia Bioelétrica/microbiologia , Eletrodos , Águas Residuárias , Eliminação de Resíduos Líquidos/métodos , Biofilmes , Técnicas Eletroquímicas/métodosRESUMO
Perchlorate and chlorate are endocrine disruptors considered emerging contaminants (ECs). Both oxyanions are commonly associated with anthropogenic contamination from fertilizers, pesticides, explosives, and disinfection byproducts. However, the soils of the Atacama Desert are the most extensive natural reservoirs of perchlorate in the world, compromising drinking water sources in northern Chile. Field campaigns were carried (2014-2018) to assess the presence of these ECs in the water supply networks of twelve Chilean cities. Additionally, the occurrence of perchlorate, chlorate and other anions typically observed in drinking water matrices of the Atacama Desert (i.e., nitrate, chloride, sulfate) was evaluated using a Spearman correlation analysis to determine predictors for perchlorate and chlorate. High concentrations of perchlorate (up to 114.48 µg L-1) and chlorate (up to 9650 µg L-1) were found in three northern cities. Spatial heterogeneities were observed in the physicochemical properties and anion concentrations of the water supply network. Spearman correlation analysis indicated that nitrate, chloride, and sulfate were not useful predictors for the presence of perchlorate and chlorate in drinking water in Chile. Hence, this study highlights the need to establish systematic monitoring, regulation, and treatment for these EC of drinking water sources in northern Chilean cities for public health protection.
Assuntos
Água Potável , Poluentes Químicos da Água , Água Potável/química , Cloratos/análise , Chile , Nitratos/análise , Percloratos , Cidades , Cloretos/análise , Poluentes Químicos da Água/análiseRESUMO
During the last decade, bioprospecting for electrochemically active bacteria has included the search for new sources of inoculum for microbial fuel cells (MFCs). However, concerning power and current production, a Geobacter-dominated mixed microbial community derived from a wastewater inoculum remains the standard. On the other hand, cathode performance is still one of the main limitations for MFCs, and the enrichment of a beneficial cathodic biofilm emerges as an alternative to increase its performance. Glucose-fed air-cathode reactors inoculated with a rumen-fluid enrichment and wastewater showed higher power densities and soluble chemical oxygen demand (sCOD) removal (Pmax = 824.5 mWm-2; ΔsCOD = 96.1%) than reactors inoculated only with wastewater (Pmax = 634.1 mWm-2; ΔsCOD = 91.7%). Identical anode but different cathode potentials suggest that differences in performance were due to the cathode. Pyrosequencing analysis showed no significant differences between the anodic community structures derived from both inocula but increased relative abundances of Azoarcus and Victivallis species in the cathodic rumen enrichment. Results suggest that this rarely used inoculum for single-chamber MFCs contributed to cathodic biofilm improvements with no anodic biofilm effects.
RESUMO
Chlorate has been described as an emerging pollutant that compromises water sources. In this study, bioelectrochemical reactors (BERs) using Dechloromonas agitata CKB, were evaluated as a sustainable alternative for chlorate removal. BERs were operated under flow-recirculation and batch modes with an applied cell-voltage of 0.44 V over a resistance of 1 kΩ. Results show chlorate removal up to 607.288 mg/L. After 115 days, scanning electron microscopy showed biofilm development over the electrodes, and electrochemical impedance spectroscopy confirmed the biocatalytic effect of CKB. The theoretical chlorate bioreduction potential (ε° = 0.792 V) was proven, and a kinetic study indicated that 6 electrons were involved in the reduction mechanism. Finally, a hypothetical bioelectrochemical mechanism for chlorate reduction in a BER was proposed. This research expands upon current knowledge of novel electrochemically active microorganisms and widens the scope of BER applications for chlorate removal.
Assuntos
Cloratos , Elétrons , Betaproteobacteria , Eletrodos , OxirreduçãoRESUMO
Green roofs have many benefits, but in countries with semiarid climates the amount of water needed for irrigation is a limiting factor for their maintenance. The use of drought-tolerant plants such as Sedum species, reduces the water requirements in the dry season, but, even so, in semiarid environments these can reach up to 60 L m-2 per day. Continuous substrate/soil water content monitoring would facilitate the efficient use of this critical resource. In this context, the use of plant microbial fuel cells (PMFCs) emerges as a suitable and more sustainable alternative for monitoring water content in green roofs in semiarid climates. In this study, bench and pilot-scale experiments using seven Sedum species showed a positive relationship between current generation and water content in the substrate. PMFC reactors with higher water content (around 27% vs. 17.5% v/v) showed larger power density (114.6 and 82.3 µW m-2 vs. 32.5 µW m-2). Moreover, a correlation coefficient of 0.95 (±0.01) between current density and water content was observed. The results of this research represent the first effort of using PMFCs as low-cost water content biosensors for green roofs.
Assuntos
Fontes de Energia Bioelétrica , Conservação dos Recursos Naturais , Plantas , Solo , ÁguaRESUMO
Pese a que la terapia de transfusión sanguínea es generalmente segura, debería ser entendido que ciertos riesgos acompañan a la transfusión de sangre y hemoderivados. Las reacciones transfusionales se clasifican en agudas y tardías. Las reacciones transfusionales agudas se presentan como signos y síntomas adversos hasta 24 horas después de la transfusión sanguínea. Las reacciones más frecuentes son: fiebre, escalofrió, urticaria, dificultad respiratoria, las cuales se resuelven pronto sin un tratamiento específico ni complicaciones. Las complicaciones más serias como la hemólisis o sepsis son potencialmente fatales. Las reacciones transfusionales requieren un reconocimiento inmediato, investigación laboratorial y manejo clínico. Debe realizarse un chequeo minucioso de la etiqueta de la unidad de sangre y del paciente. Las reacciones transfusionales agudas pueden presentarse en situaciones clínicas complejas cuando se precisa distinguir entre un diagnóstico de reacción de vida a la transfusión de un producto sanguíneo y una complicación coincidental de la enfermedad tratada que ocurre durante o inmediatamente después de una transfusión. El presente es un estudio epidemiológico descriptivo retrospectivo para determinar la incidencia y caracterizar los determinantes de transfusiones sanguíneas en pacientes del Servicio de Medicina Transfusional del Hospital Eugenio Espejo entre enero 2005 y diciembre 2007.
Assuntos
Transfusão de SangueRESUMO
The odor emitted by a patient may be one of the first major clues leading to an early diagnosis. Certain conditions produce a characteristic smell and several diseases are associated with a specific odor. We report an illustrative case and review olfactory physiology, the value of smell in physical examination, and finally discuss several illnesses associated with unusual odors.
Assuntos
Corpos Estranhos/diagnóstico , Cavidade Nasal , Odorantes , Olfato , Pré-Escolar , Equimose/etiologia , Feminino , Corpos Estranhos/complicações , Reação a Corpo Estranho/etiologia , Humanos , Doenças Nasais/etiologiaRESUMO
The odor emitted by a patient may be one of the first major clues leading to an early diagnosis. Certain conditions produce a characteristic smell and several diseases are associated with a specific odor. We report an illustrative case and review olfactory physiology, the value of smell in physical examination, and finally discuss several illnesses associated with unusual odors.
RESUMO
Se procuró determinar si el instrumento precitado, era capaz de medir en población chilena, el funcionamiento familiar en situaciones de crisis, a través de las estrategias de enfrentamiento utilizadas: obtención del apoyo social, reestructuración, búsqueda de apoyo espiritual, movilización familiar para obtener y aceptar ayuda y evaluación pasiva. La población del estudio constituida por familias, usuarias de los CESFAM de Higueras, Hualpencillo, Penco y San Vicente, y que aplicado al criterio de expertos, se distribuyan equitativamente, y que se encuentren en situación de crisis y sin crisis. Para determinar la muestra se empleó un procedimiento no probabilístico para la selección muestral, es decir, una muestrsa dirigida, suponiendo un procedimiento; dependiente del juicio de expertos. El total de la población corresponde a 5494 familias. Seleccionando en este caso al 3 por ciento de ellas, bajo el criterio de los expertos. Quedando finalmente una muestra compuesta de 163 familias. Los resultados más relevantes del estudio fueron, para la población chilena donde fue aplicado el F-COPES, que en términos de confiabilidad y validez no se ajustó al modelo teórico y a los resultados empíricos de otras investigaciones. La escala original, compuesta por 5 factores no se relacionó adecuadamente con los 5 factores obtenidos por la investigación. Finalmente el hallazgo más relevante, es la detección de un factor general dominante, de naturaleza bipolar, que capturo lo central del constructo. Denominándosele conductas de enfrentamiento. Tanto su confiabilidad y validez son satisfactoriamente adecuadas. Registrando ventajas en términos de un menor tiempo y costo para su aplicación, aportando igualmente información relevante.