Biodegradation of petroleum by bacteria isolated from fishes of Indian Ocean / Biodegradação do petróleo por bactérias isoladas de peixes do oceano Índico

In this study, oil degrading bacteria discovered from fish living near the oil ports at Karachi in Pakistan were characterized. The bacteria isolated from skin, gills, and gut in fish could consume crude oil as a source of carbon and energy. Total 36 isolates were tested using Nutrient Agar (NA) and MSA media with different crude oil concentrations (0.2%, 0.5%, 0.7%, 1%, 2%, and 5%) and 4 out of 36 isolates (two Gram positive and two Gram negative bacteria) were selected for further identification. 16S rRNA gene sequencing revealed that the isolates are related to Bacillus velezensis, Bacillus flexus, Pseudomonas brenneri and Pseudomonas azotoforman. Oil degrading potential of these bacteria was characterized by GC-MS analysis of degradation of oil components in crude oil as well as engine oil. We found that one (2, 6, 10, 14-Tetramethylpentadecane) out of 42 components in the crude oil was fully eliminated and the other oil components were reduced. In addition, 26 out of 42 oil components in the engine oil, were fully eliminated and the rest were amended. Taken together, these studies identify that B. velezensis, B. flexus, P. brenneri and P. azotoforman have high oil degrading potential, which may be useful for degradation of oil pollutants and other commercial applications.

Neste estudo, bactérias degradadoras de óleo descobertas em peixes que vivem perto dos portos de petróleo em Karachi, no Paquistão, foram caracterizadas. As bactérias isoladas da pele, guelras e intestinos dos peixes podem consumir petróleo bruto como fonte de carbono e energia. No total, 36 isolados foram testados usando Agar Nutriente (NA) e meio MSA com diferentes concentrações de óleo bruto (0,2%, 0,5%, 0,7%, 1%, 2% e 5%) e 4 de 36 isolados (dois Gram positivos e duas bactérias Gram negativas) foram selecionadas para posterior identificação. O sequenciamento do gene 16S rRNA revelou que os isolados estão relacionados a Bacillus velezensis, Bacillus flexus, Pseudomonas brenneri e Pseudomonas azotoforman. O potencial de degradação do óleo dessas bactérias foi caracterizado pela análise de GC-MS da degradação dos componentes do óleo no óleo cru, bem como no óleo do motor. Descobrimos que um (2, 6, 10, 14-tetrametilpentadecano) de 42 componentes do óleo cru foi totalmente eliminado e os outros componentes do óleo foram reduzidos. Além disso, 26 dos 42 componentes do óleo do motor foram totalmente eliminados e o restante corrigido. Juntos, esses estudos identificam que B. velezensis, B. flexus, P. brenneri e P. azotoforman têm alto potencial de degradação de óleo, o que pode ser útil para a degradação de poluentes de óleo e outras aplicações comerciais.

Characterization of the biosorption of fast black azo dye K salt by the bacterium Rhodopseudomonas palustris 51ATA strain

BACKGROUND: Removal of dyes from wastewater by microorganisms through adsorption, degradation, or accumulation has been investigated. Biological methods used for dye treatment are generally always effective and environmentally friendly. In this study, biosorption of the Fast Black K salt azo dye by the bacterium Rhodopseudomonas palustris 51ATA was studied spectrophotometrically, at various pH (2­10), temperatures (25°C, 35°C, and 45°C) and dye concentrations (25­400 mg L-1). RESULTS: The bacterial strain showed extremely good dye-removing potential at various dye concentrations. IR studies at different temperatures showed that the dye was adsorbed on the bacterial surface at lower temperatures. Characteristics of the adsorption process were investigated by Scatchard analysis at 25°C and 35°C. Scatchard analysis of the equilibrium binding data for the dye on this bacterium gave rise to linear plots, indicating that the Langmuir model could be applied. The regression coefficients obtained for the dye from the Freundlich and Langmuir models were significant and divergence from the Scatchard plot was observed. CONCLUSION: The adsorption behavior of the dye on this bacterium was expressed by the Langmuir, Freundlich, and Temkin isotherms. The adsorption data with respect to various temperatures provided an excellent fit to the Freundlich isotherm. However, when the Langmuir and Temkin isotherm models were applied to these data, a good fit was only obtained for the dye at lower temperatures, thus indicating that the biosorption ability of R. palustris 51ATA is dependent on temperature, pH, and dye concentration.

Bioremediation of heavy metals in food industry: application of Saccharomyces cerevisiae

Heavy metals are natural elements in the Earth's crust that can enter human food through industrial or agricultural processing, in the form of fertilizers and pesticides. These elements are not biodegradable. Some heavy metals are known as pollutants and are toxic, and their bioaccumulation in plant and animal tissues can cause undesirable effects for humans; therefore, their amount in water and food should always be under control. The aim of this study is to investigate the conditions for the bioremediation of heavy metals in foods. Various physical, chemical, and biological methods have been used to reduce the heavy metal content in the environment. During the last decades, bioremediation methods using plants and microorganisms have created interest to researchers for their advantages such as being more specific and environmentally friendly. The main pollutant elements in foods and beverages are lead, cadmium, arsenic, and mercury, which have their own permissible limits. Among the microorganisms that are capable of bioremediation of heavy metals, Saccharomyces cerevisiae is an interesting choice for its special characteristics and being safe for humans, which make it quite common and useful in the food industry. Its mass production as the byproduct of the fermentation industry and the low cost of culture media are the other advantages. The ability of this yeast to remove an individual separated element has also been widely investigated. In countries with high heavy metal pollution in wheat, the use of S. cerevisiae is a native solution for overcoming the problem of solution. This article summarizes the main conditions for heavy metal absorption by S. cerevisiae.

Determinación preliminar de triclosán por espectroscopia UV-Vis en aguas residuales de la ciudad de Guatemala / Preliminary determination of triclosan by UV-Vis spectroscopy in wastewater from Guatemala city

Estimar el grado de remoción de contaminantes emergentes en el proceso de tratamiento de aguas residuales es de importancia para evaluar la efectividad de las técnicas empleadas en la actualidad. El triclosán (TCS) es un agente antimicrobiano sintético de amplio espectro, estudios recientes sugieren que presenta elevado potencial como interruptor endocrino. Se determinó la concentración de TCS en cuatro muestras de aguas residuales obtenidas en diferentes etapas del proceso de tratamiento de aguas en la Planta Piloto para el Tratamiento de Aguas Residuales Ingeniero Arturo Pazos Sosa (IAPS). Las muestras de agua fueron filtradas en membrana, tratadas por adición de TCS estándar y formación de un compuesto complejo coloreado amarillo-café cuya absorbancia a 475 nm fue registrada en un espectrofotómetro Cary® 50 UV-Vis. Se identificó la presencia de TCS en concentraciones por arriba de 200 µg/L en tres diferentes etapas del tratamiento de aguas residuales en la planta piloto IAPS lo que permitió concluir que el grado de remoción de TCS en esta planta de tratamiento de aguas osciló entre 31 y 95% dependiendo de la etapa de tratamiento, sin embargo el agua del efluente de la planta no puede considerarse como potable ya que la concentración de TCS determinada en este estudio sobrepasa por al menos un orden de magnitud de diez los niveles a los cuales no se han reportado efectos adversos hacia organismos vivos.

Estimating the degree of contaminants' removal during wastewater treatment is important to evaluate the effectiveness of the current treatment techniques. Triclosan (TCS) is a synthetic broad spectrum antimicrobial agent and recent investigations suggest that this compound has high potential as endocrine disruptor. The concentration of TCS was measured in four wastewater samples obtained at different processing steps at the Ingeniero Arturo Pazos Sosa (IAPS) pilot plant. The wastewater samples were treated by membrane filtration, standard addition of TCS and the subsequent formation of a brown-yellow colored complex, whose absorbance at 475nm was measured in a Cary 50® UV-Vis spectrophotometer. TCS was found at concentrations over 200 µg/L in three different phases of the wastewater treatment at the IAPS plant. In conclusion, the degree of TCS removal in this plant was between 31 and 95% depending on the treatment stage. However plant effluent cannot be considered potable since the TCS concentration found in this study is at least ten times higher than those at which adverse effects to living organisms have not been detected.

Eficiencia en la reducción de Cromo por una bacteria silvestre en un tratamiento tipo Batch utilizando como sustrato agua residual del municipio de Pasto, Colombia / Efficiency in the reduction of chromium by a wild bacterium in a Batch treatment type using residual water substrate from the municipality of Pasto, Colombia

Resumen Objetivo: Evaluar la eficiencia en la reducción de Cromo en un tratamiento tipo Batch, utilizando como sustrato agua residual municipal inoculada con una bacteria silvestre. Materiales y métodos: Se verificó a escala de laboratorio el porcentaje de reducción de Cromo hexavalente de tres bacterias silvestres previamente aisladas de agua residual del Río Pasto (Bacillus thuringiensis, Bacillus amyloliquefaciens y Paenibacillus sp.); se seleccionó el aislado que presentó mayor porcentaje de reducción de Cr y fue sometido a diferentes tratamientos. El análisis de los resultados se hizo mediante estadística descriptiva. Resultados: B. thuringiensis, B. amyloliquefaciens, y Paenibacillus sp., presentaron porcentajes de reducción de Cr (VI) de 82,01%; 80,85% y 79,27%, respectivamente. Se determinó que el tercer tratamiento (agua sin esterilizar del Río Pasto con B. thuringiensis) presentó diferencias significativas respecto a los demás (p = 0,0001 α = 0,05), concluyendo que B. thuringiensis reduce en mayor proporción el Cr (VI), los resultados encontrados en esta investigación son promisorios en el campo de la biorremediación de efluentes contaminados con Cromo ya que pueden ser tomados como base para implementar estrategias de biorremediación a gran escala. Conclusión: La bacteria B. thuringiensis presentó alta eficiencia en la reducción de Cromo hexavalente (99,42%), cuando fue implementada en un tratamiento a escala de laboratorio de agua residual sin esterilizar.

Abstract Objective: To evaluate the efficiency in the reduction of chromium in a Batch treatment type, using municipal residual water substrate inoculated with a wild bacterium. Materials and methods: The reduction percentage of hexavalent chromium of three wild bacteria previously isolated from residual water from the Pasto River was verified at laboratory scale (Bacillus thuringiensis, Bacillus amyloliquefaciens and Paenibacillus sp.); the isolated that showed the highest percentage of reduction of Cr was selected and was subjected to different treatments. The analysis of results was done using descriptive statistics. Results: B. thuringiensis, B. amyloliquefaciens, and Paenibacillus sp., presented percentages of reduction of Cr (VI) of 82,01%; 80,85% and 79,27%, respectively. It was determined that the third treatment (nonsterile water from the Pasto River with B. thuringiensis) presented significant differences with regard to the other (p = 0.0001 α = 0.05), concluding that B. thuringiensis reduces in greater proportion the Cr (VI). The results found in this research are promising in the field of bioremediation of contaminated effluents with Chrome since they may be taken as the basis for implementing strategies of bioremediation on a large scale. Conclusion: The bacteria B. thuringiensis presented high efficiency in the reduction of hexavalent chromium (99.42%) when implemented in a treatment at laboratory scale of residual nonsterile water.

Remediación de residuos sólidos contaminados con Cr(vi) por un hongo filamentoso / Remediation of waste contaminated with Cr (VI) by a filamentous fungus

La biotecnología ambiental recurre a organismos capaces de reducir los niveles de metales pesados, entre ellos el Cr(VI), contenido en residuos y efluentes agroindustriales. El objetivo del trabajo fue estudiar la biorremediación de un residuo como pulpa de limón contaminada con Cr(VI) y el efecto del metal sobre el crecimiento fúngico. Se utilizaron tres hongos filamentosos como Aspergillus niger; Penicillium expansum y P. islandicum para remediar pulpa de limón (residuo) contaminada con Cr(VI) (50 mg/L) que se realizó en las siguientes condiciones de cultivo: la pulpa se suplementó con urea, 0,006; (NH4) 2SO4, 0,012; KH2PO4,0,003 y KCl, 0,001 g/ g; 105 conidios/g, a pH 2,5, 30°C y 96 h de incubación. Se estudió el efecto tóxico de diferentes concentraciones (5; 10; 20 y 50 mg/L) del metal sobre el desarrollo del hongo de mayor eficiencia de remediación (Ef. por ciento). Aspergillus niger; obtuvo mayor EF. de remediación (97 por ciento) respecto a Penicillium expansum (95 por ciento) y P. islandicum (94 por ciento), del residuo contaminado con 50 mg/L de Cr(VI). Se determinó que la presencia de Cr(VI) y no su concentración estimuló la maduración temprana (48 h) de los conidios (blancos a negros) de A. niger, sin que se observe alteraciones en el micelio con respecto al control (72h), desarrollado en la pulpa sin el metal. En conclusión, A. niger fue más resistente y presentó altas Ef. de remediación de Cr(VI) de residuos sólidos, este proceso es una alternativa a las tecnologías físico-químicas, debido que los microorganismos pueden remover selectivamente diferentes iones de zonas contaminadas.

Environmental biotechnology uses organisms capable of reducing levels of heavy metals, including the Cr (VI), contained in waste and agro-industrial effluents. The objective of this work was to study bioremediation of waste contaminated with Cr(VI) lemon pulp and the effect of the metal on the fungal growth. We used three filamentous fungi such as Aspergillus niger; Penicillium expansum and P. islandicum to remedy pulp from lemon (residue) contaminated with Cr(VI) (50 mg/L) that was conducted in the following conditions of cultivation: the pulp is supplemented with urea, 0.006; (NH4) 2SO4, 0.012; KH2PO4, 0.003 and KCl, 0.001 g / g; 105 conidia/g, at pH 2.5, 30 ° C and 96 h of incubation. We studied the toxic effect of different concentrations (5, 10, 20 and 50 mg/L) of the metal on the development of the fungus increased efficiency of remediation (Ef. percent). Aspergillus niger; obtained greater EF. remediation (97 percent) with respect to Penicillium expansum (95 percent) and P. islandicum (94 percent), 50 mg/L of Cr (VI)-contaminated waste. It was determined that the presence of Cr (VI) and not its concentration stimulated early maturation (48 h) of conidia (white on black) from A. niger, unless you observe alterations in the mycelium as compared to the control (72 h), developed in the pulp without the metal. In conclusion, A. niger was stronger and presented high Ef. remediation of Cr (VI) waste, this process is an alternative to physico-chemical technologies, due to the micro-organisms be removed selectively different ions from contaminated areas.

Removal of lead, mercury and nickel using the yeast Saccharomyces cerevisiae / Remoción de plomo, mercurio y níquel utilizando la levadura Saccharomyces cerevisiae

Objective. In this study the biomass of the yeast Saccharomyces cerevisiae was used to remove lead, mercury and nickel in the form of ions dissolved in water. Materials and methods. Synthetic solutions were prepared containing the three heavy metals, which were put in contact with viable microorganisms at different conditions of pH, temperature, aeration and agitation. Results. Both individual variables and the interaction effects influenced the biosorption process. Throughout the experimental framework it was observed that the biomass of Saccharomyces cerevisiae removed a higher percentage of lead (86.4%) as compared to mercury and nickel (69.7 and 47.8% respectively). When the pH was set at a value of 5 the effect was positive for all three metals. Conclusions. pH was the variable that had a greater influence on the biosorption of lead on the biomass of Saccharomyces cerevisiae. The affinity of the heavy metals for the biomass followed the order Pb>Hg>Ni.

Objetivos. En este estudio se utilizó la biomasa de la levadura Saccharomyces cerevisiae para retener plomo, mercurio y níquel en forma de iones disueltos en agua. Materiales y métodos. Se prepararon soluciones sintéticas que contenían los tres metales pesados, las cuales se pusieron en contacto con el microorganismo en forma viable a diferentes condiciones de pH, temperatura, aireación y agitación. Resultados. Tanto las variables individuales como los efectos de interacción influyeron sobre el proceso de biosorción. A través de todos los experimentos, se observó que la biomasa de Saccharomyces cerevisiae eliminó un mayor porcentaje de plomo (86.4%) en comparación al mercurio y al níquel (69.7 y 47.8% respectivamente). Cuando el pH se fijó en valor de 5, el efecto fue positivo para los tres metales. Conclusiones. El pH fue la variable que tuvo una mayor influencia en la biosorción de plomo sobre la biomasa de Saccharomyces cerevisiae. La afinidad de los metales pesados por la biomasa siguió el orden Pb>Hg>Ni.

Constructed wetlands for domestic wastewater treatment in a Mediterranean climate region in Chile

Background: Constructed wetlands are a promising, cheap and effective wastewater treatment in small communities. The studies on these systems have been reported mainly from cold, tropical or subtropical climate regions. In this work we constructed a pilot plant with six horizontal subsurface flow constructed wetlands (HSSF CWs) with a surface area of 2 m² and a depth of 0.6 m each, planted with Typha latifolia or Scirpus sp., and filled with gravel (G) or fine gravel (FG) of 2.8 and 1.2 cm of diameter respectively, continuously fed with raw domestic wastewater. This experimental setup was evaluated over 280 days for the removal of organic matter and nutrients in a Mediterranean climate, near Valparaíso, Chile. The removal of total COD, NH4+-N and PO4-3-P was calculated, in order to assess by analysis of variance the effect of initial pollutants concentration, air temperature (season) and plant/support combination on the wetlands performance. Results: The Scirpus/FG combination showed the highest average removal of total COD of about 59%, and Typha/FG shows the highest removal of NH4+-N and PO4-3-P (49 and 32%, respectively). Furthermore, the removal of organic matter was independent of influent concentration, while mildly dependent of the season, unlike nutrients removal that was dependent on these two parameters. Media, plant and the plant/media combination influenced positively organic matter, ammonia and phosphorous removal, respectively. Conclusions: Overall, the results demonstrate the potential of wetlands in treatment of wastewater in Mediterranean regions and show how these can help to improve the quality of water in domestic zones without high-throughput technologies.

Selection of white-rot fungi to formulate complex and coated pellets for Reactive Orange 165 decolourization

Six strains of white-rot fungi isolated from southern Chile were evaluated for their ergosterol/biomass correlation and ligninolytic potential in solid medium to formulate pellets for Reactive Orange 165 (RO165) decolourization. The fungus Anthracophyllum discolor was selected to formulate complex pellets (fungal mycelium, sawdust, and activated carbon), coated pellets (complex pellet + alginate) and simple pellets (fungal mycelium). The activity of ligninolytic enzymes (laccase, manganese peroxidase, manganese-independent peroxidase, and lignin peroxidase) was evaluated in both the complex and coated pellets in modified Kirk medium, and the morphology of the pellets was studied using scanning electron microscopy (SEM). Complex pellets of A. discolor showed a higher enzymatic production mainly MnP (38 U L-1 at day 15) compared to coated and simple pellets. Examinations using SEM showed that both pellets produced a black core that was entrapped by a layer of fungal mycelium. Decolourization of RO165 was demonstrated with all the pellets formulated. However, the highest and fastest decolourization was obtained with complex pellets (100 percent at day 8). Therefore, complex pellets of A. discolor can be used for the biological treatment of wastewater contaminated with RO165.

Aplicación de métodos electroquímicos en la remoción de materia orgánica en los jugos producto del beneficio del fique: alternativa biotecnológica para mitigar la contaminación en los afluentes hídricos / Application of electrochemical methods in the removal of organic matter in the juices of the benefit of sisal products: biotechnological alternative for mitigating water pollution in the tributaries

Esta investigación tuvo como propósito aplicar las tecnologías electroanalíticas, como la electrocoagulación, para la remoción de materia orgánica presente en los jugos del fique con el fin de reducir el impacto ambiental que genera una práctica milenaria y cultural como lo es la extracción de la fibra (cabuya) de la Fourcrea c. En el presente estudio, se evaluó el comportamiento de la demanda química de oxígeno (DQO) a través del proceso electroquímico bajo diferentes parámetros de corriente eléctrica, voltaje y pH para evaluar los parámetros óptimos de operación en el tratamiento de estas aguas residuales, lo cual permitió modelar matemáticamente la respuesta de este proceso y plantear una alternativa para mitigar la contaminación generada en los cuerpos de agua.

Biosurfactant production by Rhodococcus erythropolis and its application to oil removal

The influence of different nutrients on biosurfactant production by Rhodococcus erythropolis was investigated. Increasing the concentration of phosphate buffer from 30 up through 150 mmol/L stimulated an increase in biosurfactant production, which reached a maximum concentration of 285 mg/L in shaken flasks. Statistical analysis showed that glycerol, NaNO3,MgSO4 and yeast extract had significant effects on production. The results were confirmed in a batchwise bioreactor, and semi-growth-associated production was detected. Reduction in the surface tension, which indicates the presence of biosurfactant, reached a value of 38 mN/m at the end of 35 hours. Use of the produced biosurfactant for washing crude oil-contaminated soil showed that 2 and 4 times the critical micellar concentration (CMC) were able to remove 97 and 99 percent of the oil, respectively, after 1 month of impregnation.

Isolation of purple nonsulfur bacteria for the removal of heavy metals and sodium from contaminated shrimp ponds

In order to determine whether waters used for the shrimp cultivation contained toxic levels of heavy metals (HMs) and sodium (Na), analysis was carried out on 31 shrimp ponds in areas of southern Thailand. Purple nonsulfur bacteria (PNB) were also isolated from the same ponds to investigate if they could be used for bioremediation of the above contaminants. The highest HMs concentrations of the sediment samples in mg/kg dry weight were found as follows: 0.75 cadmium (Cd), 62.63 lead (Pb), 34.60 copper (Cu) and 58.50 zinc (Zn). However, all sediment samples met Hong Kong standards for dredged sediment. In contrast, contamination of Cu (9-30 ug/L) and Zn (140-530 ug/L) exceeding the standard guidelines for marine aquatic animal set by the Pollution Control Department, Thailand, were found in 32 and 61 percent of water samples, respectively. Two metal resistant PNB isolates, NW16 and KMS24, were selected from the 120 PNB isolates obtained. Both isolates reduced the levels of HMs by up to 39 percent for Pb, 20 percent for Cu, 7 percent for Cd, 5 percent for Zn and 31 percent for Na from water that contained the highest levels of HMs found and 3 percent NaCl when cultured with either microaerobic-light or aerobic-dark conditions. The isolate NW16 removed a greater percentage of the HMs than the isolate KMS24, but the isolate KMS24 was able to survive better under a greater variety of environmental conditions. Both strains were therefore suitable to use for further investigating their abilities to remediate water contaminated with HMs and Na.

Plantio e desempenho fenológico da taboa (Thypha sp.) utilizada no tratamento de esgoto doméstico em sistema alagado construído / Planting and fenological performance of Thypha sp used in the domestic wastewater treatment under constructed wetland system

Este trabalho teve por objetivo estudar o desempenho da macrófita taboa (Typha sp.) e a remoção de nutriente pela mesma, cultivada em quatro sistemas alagados construídos (SAC), utilizados no tratamento de efluente doméstico, pro-veniente de tanque séptico. Para tanto, foram avaliados órgãos vegetais e quantificadas as seguintes variáveis na água residuária e no tecido vegetal: nitrogênio total (N-Total), fósforo total (P-Total), sódio (Na) e potássio (K). Obtendo-se, como resultado, profundidade média de 27,15 cm, alcançada pelas raízes, bom desenvolvimento da taboa, o que possibilitou a partida do sistema aos quatro meses após o estabelecimento da vegetação e, por meio da remoção da biomassa aérea, contribuição para remoção de 1,69 por cento, 1,64 por cento, 4,94 por cento e 0,74 por cento do aporte de N-Total, P-Total, potássio e sódio, respectivamente.

This study was carried out in under to evaluate the macrophytes (Typha sp) performance and nutrient removal by the same, cropped in four constructed wetlands (SACs), used in treating the domestic wastewater proceeding from septic tank. So, were evaluated vegetable organ and the following variables quantified in either wastewater and vegetable tissue: total nitrogen (N-total), total phosphorus (P-total), sodium (Na) and potassium (K). An average depth of 27.15cm were reached by roots, as well as a satisfactory development of Thypha sp., therefore making possible to beginning the operation of the system at four months after vegetation establishment. The system made possible the following removals of the aerial biomass: 1.69 percent, 1.64 percent, 4.94 percent and 0.74 percent from the contribution of N-total, P-total, potassium and sodium, respectively.

Impacto dos mediadores redox na remoção de cor de corantes azo e antraquinônico por lodo granular anaeróbio sob condições mesofílicas e termofílicas / Impact of redox mediators on colour removal of azo and anthraquinone dyes by anaerobic granular sludge under mesophilic and thermophilic conditions

Investigou-se o efeito de diferentes mediadores redox (MR) na remoção de cor de corantes azo e antraquinônico pelo uso de lodo granular anaeróbio sob condições mesofílicas (30ºC) e termofílicas (55ºC). Comprovou-se em experimento em batelada que a adição de concentrações catalíticas de MR pode ter um efeito marcante nas taxas de descoloração do corante azo Reactive Red 2 (RR2), mas o mesmo comportamento não pode ser obtido com o corante antraquinônico Reactive Blue 5 (RB5). Entretanto, com ambos os corantes, o simples aumento da temperatura de incubação para condições termofílicas fez acelerar consideravelmente os processos de descoloração, comparados com condições mesofílicas. Por exemplo, a constante de primeira ordem "k" da redução dos corantes RR2 e RB5, foi aumentada em 6,2 e 11 vezes, respectivamente, à 55ºC quando comparado com 30ºC. Por fim, comprovou-se em experimentos de fluxo contínuo, a boa performance do tratamento termofílico na descoloração redutiva de corantes azo.

The effect of different redox mediators (RM) on colour removal of azo and anthraquinone dyes was investigated with anaerobic granular sludge under mesophilic (30ºC) and thermophilic (55ºC) conditions. Batch experiments revealed that an addition of catalytic concentrations of RM provided a remarkable effect on the decolourisation rates of the azo dye Reactive Red 2 (RR2), but the same effect could not be obtained with the anthraquinone dye Reactive Blue 5 (RB5). Nevertheless, for both dyes, the temperature increase to thermophilic conditions was an effective strategy to considerably accelerate the decolourisation process compared to mesophilic conditions. For instance, the first-order rate constant "k" of RR2 and RB5 reduction, was increased in 6.2 and 11-fold, respectively, at 55ºC in comparison with 30ºC. Such an effect of the temperature on the reductive decolourisation of azo dye was also verified in continuous flow experiments.

Evaluación de un modelo piloto integrado para postratamiento del efluente del RAP utilizando Spirodela sp / Evaluating an integrated pilot model for post-treatment of RAP effluent using Spirodela Sp

Los sistemas integrados de tratamiento de aguas residuales buscan la disminución de materias orgánicas y nutrientes, además de la reutilización de los subproductos generados en el proceso. Para complementar la eficiencia de remoción de nutrientes del actual tratamiento de las aguas residuales de la Universidad Pontificia Bolivariana Bucaramanga se construyó un modelo piloto integrado con Spirodela sp., el cual fue evaluado para medir la eficiencia en remoción de nutrientes (nitrógeno y fósforo), coliformes totales y fecales, con diferentes alturas de lámina de agua; los resultados reportaron eficiencias hasta de 77.07 por cien para nitrógeno amoniacal, 97.10 por cien fósforo total, 98.56 por cien coliformes fecales y 96.4 por cien coliformes totales.

The effectiveness of alcohol gel and other hand-cleansing agents against important nosocomial pathogens

Nós comparamos a eficácia do álcool gel com a dos tradicionais agentes degermantes preconizados para a lavagem das mãos na remoção de amostras clínicas de Acinetobacter baumannii, Staphylococcus aureus resistente a meticilina, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa e Candida albicans das mãos artificialmente contaminadas. As pontas dos dedos dos voluntários (n=6) foram contaminadas com aproximadamente 106 de células/microrganismo teste. A seguir, as mãos foram lavadas com sabonete líquido não medicamentoso, álcool gel, álcool etílico 70 per center (concentração por peso) e soluções anti-sépticas detergentes de polivinilpirrolidona-iodo a 10 per center (PVP-I) e de gluconato de clorhexidina 4 per center. Os experimentos foram realizados segundo um quadrado latino com seis blocos aleatorizados 6 x 5. Os resultados foram estimados por ANOVA. Os produtos reduziram de 93,83 per center (sabão líquido) a 100 per center (PVP-I 10 per center) a população microbiana aplicada nas mãos. Em 4 dos 6 microrganismos testes analisados, o PVP-I 10 per center, o álcool gel, o álcool etílico 70 per center e a clorhexidina 4 per center mostraram uma taxa de remoção significantemente superior a do sabão líquido (P < 0,05). Os resultados confirmam a eficácia do álcool gel na higienização das mãos e sugerem que o PVP-I 10 per center, o álcool gel, o álcool etílico 70 per center e a clorhexidina 4 per center podem ser os agentes mais eficazes do que o sabão líquido não medicamentoso na remoção de Acinetobacter baumannii, Escherichia coli, Enterococcus faecalis e Candida albicans das mãos altamente contaminadas.

Remoçäo de nutrientes em sistemas de tratamento de esgotos pelo processo de lodos ativados por meio de aeraçäo intermitente / Capacity to remove nutrients in aeration activated sludge wastewater treatment

Objetivo: Quando se fala em esgotos sanitários, além das cargas orgânicas, os chamados macronutrientes têm sido alvo de preocupaçäo quanto à qualidade dos copos d'água. Esses compostos säo derivados de dois elementos principais: o nitrogênio e o fósforo. O objetivo do presente estudo foi o de avaliar a capacidade de remoçäo biológica de nutrientes (nitrogênio e fósforo) em estaçöes convencionais de lodos ativados por aeraçäo prolongada, por meio de operaçäo intermitente do sistema de aeraçäo. Foram avaliadas diversas configuraçöes operacionais, visando propiciar ambientes anóxicos e, se possível, anaeróbios, no próprio tanque de aeraçäo. Metodologia: Para tanto, foram implantadas em uma estaçäo de tratamento de esgotos sanitários de uma indústria, quatro configuraçöes de parada dos aeradores. Resultados: A remoçäo de fósforo ficou restrita aos 2,5 por cento incorporado normalmente pelos microrganismos. Para os compostos de nitrogênio houve bons resultados de remoçäo, alguns acima de 50 por cento, apesar de grande instabilidade provocada pela variaçäo das características do esgoto bruto e pela dificuldade de garantir a disponibilidade da matéria orgânica durante os ciclos anóxicos. Dentre os benefícios conseguidos está a recuperaçäo de parte do oxigênio consumido para a nitrificaçäo e da alcalinidade, revertendo em economia de recursos (energia e insumos), além da qualidade do efluente final que näo foi afetada negativamente pelas paradas dos aeradores. Conclusöes: Conclui-se que a remoçäo do fósforo näo foi possível devido às interferências negativas com os mecanismos de remoçäo de nitrogênio, com a constante presença de nitrato no sistema. Para o nitrogênio os resultados foram favoráveis, conseguindo recuperaçäo de oxigênio e de alcalinidade. Os estudos devem se aprofundar no sentido de se otimizar a aplicaçäo da matéria orgânica r tirar proveito de uma parada longa durante o horário de tarifa energética mais elevada

Remoçäo de fluoreto de águas para abastecimento público pelo processo de osmose reversa / Fluoride removal from drinking water by reverse osmosis process

Objetivo: Mananciais säo abandonados para o abastecimento público por possuírem quantidades excessivas de fluoreto. Este trabalho objetivou estudar a remoçäo do íon fluoreto de águas sintéticas e naturais pelo processo de osmose reversa. Metodologia: Foram utilizadas cinco águas sintéticas com concentraçöes de fluoreto de variando entre 3 e 17 mg/L, e duas águas naturais com concentraçöes de fluoreto de 3 e 12 mg/L. Os experimentos foram realizados em uma unidade de osmose reversa trabalhando por batelada, e para cada água foram realizados ensaios de osmose reversa com pressöes de 50, 75, 100, 150 e 200 psi. Foram verificadas as concentraçöes de fluoreto no permeado e no concentrado. Resultados: Para as águas sintéticas obteve-se remoçöes de fluoreto entre 60 e 89 por cento. Enquanto que para as águas naturais obteve-se remoçöes de fluoreto entre 92 e 98 por cento. Conclusäo: O processo de osmose reversa é eficiente para remover fluoreto de águas para abastecimento público. As concentraçöes de fluoreto obtidas no permeado das águas naturais foram bem abaixo do exigido pela legislaçäo para águas destinadas ao consumo humano. As concentraçöes de fluoreto obtidas no concentrado foram elevadas, devendo o seu destino final ser estudado. Os resultados obtidos para as águas sintéticas näo foram täo satisfatórios quanto os obtidos para as águas naturais.

Avaliaçäo de nova metodologia in vitro de identificaçäo e coleta microbiana no interior de canais radiculares e no material extruído durante as manobras de seu preparo / Evaluation of a new methodology in vitro identification and microbian collection inside root canal and material extruded during handling in preparing a root canal

O combate aos microrganismos contaminantes do sistema de canais é condiçäo indispensável à cura dos processos infecciosos periapicais. Por sua vez, restos orgânicos e microrganismos pré-existentes no interior do conduto, associados a aparas dentinárias resultantes do seu preparo e a substâncias químicas auxiliares podem eventualmente ser levados aos tecidos periapicais, retardando ou impedindo o processo reparacional. Através do desenvolvimento de uma nova metodologia de coleta e identificaçäo, avaliou-se, in vitro, no interior dos canais radiculares e no material extruído durante seu preparo, a viabilidade de uma associaçäo de microrganismos contendo: Enterobater aglomerans (ATCC-27.155), Enterococcus faecalis (ATCC-19433) e Pseudomonas aerunosa (ATCC-15.442), inoculados no interior de dentes extraídos, frente a três situaçöes distintas: 1) instrumentaçäo com água destilada estéril; 2) instrumentaçäo com Endo-PTC + líquido de Dakin; 3) instrumentaçäo com Endo-PTC + líquido de Dakin e esvaziamento prévio do conteúdo do canal com as mesmas substâncias. A metodologia desenvolvida, mostrou-se efetiva para fins propostos, tanto em relaçäo as coletas de material extruído quanto a identificaçäo das espécies contaminantes...