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COVID-19 pandemic has led to concerns on the circulation of SARS-CoV-2 in the environment, its infectivity from the environment and, the relevance of transmission via environmental compartments. During 31 weeks, water samples were collected from a heavily contaminated stream going through an urban, underprivileged community without sewage collection. Our results showed a statistically significant correlation between cases of COVID-19 and SARS in the community, and SARS-CoV-2 concentrations in the water. Based on the model, if the concentrations of SARS-CoV-RNA (N1 and N2 target regions) increase 10 times, there is an expected increase of 104% [95%CI: (62-157%)] and 92% [95%CI: (51-143%)], respectively, in the number of cases of COVID-19 and SARS. We believe that differences in concentration of the virus in the environment reflect the epidemiological status in the community, which may be important information for surveillance and controlling dissemination in areas with vulnerable populations and poor sanitation. None of the samples were found infectious based cultures. Our results may be applicable globally as similar communities exist worldwide.

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Biopolymers are promising materials for water treatment applications due to their abundance, low cost, expandability, and chemical structure. In this work, gelatin hydrogels filled with cellulose in the form of pristine eucalyptus residues (PER) or treated eucalyptus residues (TER) were prepared for adsorption and chromium removal in contaminated water. PER is a lignocellulosic compound, with cellulose, hemicellulose, and lignin, while TER has cellulose as a major component. FT-Raman Spectroscopy and FTIR analysis confirmed the crosslink reaction with glutaraldehyde and indicated that fillers altered the gelatin molecular vibrations and formed new hydrogen bonds, impacting the hydrogels' crystalline structure. The hydrogen bond energy was altered by the cellulosic fillers' addition and resulted in higher thermal stability (~10 °C). Hydrogels presented a Fickian diffusion, where gelatin hydrogel showed the highest swelling ability (466%), and composites showed lower values with the filler content increase. The chromium adsorption capacity presented values between 12 and 13 mg/g, i.e., featuring an excellent removal capacity which is related with hydrogel crosslinked structure and fibers surface hydroxyl groups, highlighting gelatin hydrogel TER 5% with better removal capacity. The developed hydrogels were produced from biomacromolecules with low-cost and potential application in contaminated water.

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Arsenic (As) and fluoride (F) are two common groundwater toxicants. The toxicity of As is closely related to As metabolism, and several biological and environmental factors have been associated with As modification. However, limited information about the effect of F exposure on the modification of the As metabolism profile has been described. The aim of this study was to assess the interaction effect of AsF coexposure on the As metabolism profile in an adult population environmentally exposed to low-moderate As levels. A cross-sectional study was conducted in 236 adults from three Mexican communities. F and As concentrations were quantified in water samples. The concentrations of urinary F and As species [inorganic arsenic (iAs), monomethylated arsenic (MAs) and dimethylated arsenic (DMAs)] were also determined and used as exposure biomarkers. As species percentages and methylation indices were estimated to evaluate the As methylation profile. Our results showed a relationship between the water and urine concentrations of both contaminants and, a significant correlation between the As and F concentrations in water and urine samples. A statistically significant interaction of F and As exposure on the increase in MAs% (ß = 0.16, p = 0.018) and the decrease in DMAs% (ß = -0.3, p = 0.034), PMI (ß = -0.07, p = 0.052) and SMI (ß = -0.13, p = 0.097) was observed. These findings indicate that drinking water is the main source of AsF coexposure and suggest that F exposure decreases As methylation capacity. However, additional large and prospective studies are required to confirm our findings, and to elucidate the involved mechanisms of interaction and their implications in adverse health effects.

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RESUMEN Los habitantes del sector El Terrenal, del municipio de Boavita-Boyacá, al no contar con el servicio de acueducto, utilizan las aguas del río Chicamocha, para la preparación de sus alimentos, limpieza y aseo personal. El objetivo de este estudio fue evaluar bacterias y protozoos presentes en el cuerpo de agua del río Chicamocha, a través de un análisis cuantitativo de riesgo microbiológico (ACRM). Para el desarrollo del trabajo, se realizaron cuatro muestreos, de abril a junio de 2016, en los márgenes y centro del río y un quinto muestreo de agua tratada con la planta Opuntia ficus-indica (Tuno). Se realizó el método de recuento en placa, usándose medios selectivos y diferenciales para el aislamiento de Escherichia coli, Salmonella, Enterococcus y la técnica de MacMaster, para la determinación de parásitos gastrointestinales (PGI). Para el análisis de la información, se emplearon los estadísticos no paramétricos de Kruskall-Wallis y U-Mann Whitney. Se determinó que, al menos, un lugar de muestreo es estadísticamente diferente a otro para Enterococcus faecium (P= 0,000) y los ooquistes de Entamoeba histolytica (P= 0,000). Por el contrario, para Escherichia coli no se observaron diferencias significativas entre las zonas, pero sí al menos una fecha de muestreo fue estadísticamente diferente (P= 0,026) a otra. En el agua tratada, se observó una disminución de los ooquistes de E. histolytica y un aumento en el porcentaje de E. faecium (P= 0,035).

ABSTRACT The habitants of the El Terrenal sector of the municipality of Boavita-Boyacá, have no access to the aqueduct service, and use water of the Chicamocha River for preparation of food, housework and personal hygiene. The aim of this study was to evaluate the presence of pathogenic bacteria and protozoa, present in the water body of the Chicamocha River, through a quantitative analysis of microbiological risk (ACRM). For the development of the work, four samples were conducted from April to June 2016, in the margins and center of the river, and a fifth sample of water treated with the plant Opuntia ficus-indica (Tuno). The method of plate count was performed, using selective and differential media for the isolation of Escherichia coli, Salmonella, Enterococcus and the MacMaster technique for the determination of gastrointestinal parasites (PGI). For the analysis of the information the nonparametric statistics of Kruskall Wallis and U-Mann Whitney were used. It was determined that at least one sampling site is statistically different from another for Enterococcus faecium (P = 0.000) and the oocysts of Entamoeba histolytica (P = 0.000). In contrast, for Escherichia coli no significant differences were observed between the zones, but if at least one sampling date was statistically different (P =0.026) to another. In the treated water there was a decrease in the oocysts of E. histolytica and an increase in the percentage of E. faecium (P= 0,035).

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The effect of different microaeration flow rates and dosing points, and of effluent recirculation, on microaerobic BTEX degradation in an anaerobic bioreactor was assessed. Additionally, a sensitivity and recovery analysis for this system was performed during microaeration failure simulations. Under anaerobic conditions, BTEX removal efficiencies between 55 and 82% were achieved depending on the compound, being benzene the most recalcitrant one. Microaeration (0.5-2.0 mL air min-1) ensured high removal efficiencies (>83%) for all compounds, and the best results were obtained for the flow rate of 1.0 mL air min-1, particularly for benzene, with a 30% increase in its removal efficiency. Effluent recirculation showed to be an important factor to improve mass transfer and, consequently, BTEX removal. Volatilization was negligible even under microaerobic conditions, suggesting that microbial activity was the main removal mechanism. Finally, after microaeration shutdown periods, the bioreactor could recover its prior performance within up to 2 days.

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As the addition of low concentrations of oxygen can favor the initial degradation of benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds, this work verified the applicability of the microaerobic technology to enhance BTEX removal in an anaerobic bioreactor supplemented with high and low co-substrate (ethanol) concentrations. Additionally, structural alterations on the bioreactor microbiota were assessed throughout the experiment. The bioreactor was fed with a synthetic BTEX-contaminated water (~ 3 mg L-1 of each compound) and operated at a hydraulic retention time of 48 h. The addition of low concentrations of oxygen (1.0 mL min-1 of atmospheric air at 27 °C and 1 atm) assured high removal efficiencies (> 80%) for all compounds under microaerobic conditions. In fact, the applicability of this technology showed to be viable to enhance BTEX removal from contaminated waters, especially concerning benzene (with a 30% removal increase), which is a very recalcitrant compound under anaerobic conditions. However, high concentrations of ethanol adversely affected BTEX removal, especially benzene, under anaerobic and microaerobic conditions. Finally, although bacterial community richness decreased at low concentrations of ethanol, in general, the bioreactor microbiota could deal with the different operational conditions and preserved its functionality during the whole experiment.

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ResumenLa carpa común (Cyprinus carpio) es un organismo acuático de valor comercial que puede sobrevivir en ambientes contaminados; la carpa contiene enzimas proteolíticas de importancia fisiológica y potencial aplicación industrial. El objetivo de este estudio fue purificar parcialmente y determinar la actividad proteolítica a diferente pH de proteasas de carpas colonizando un ambiente contaminado. Se capturaron tres carpas en diferentes zonas de la laguna contaminada de Zumpango (México) a 1 m de profundidad máxima. El extracto crudo se obtuvo del músculo dorsal mediante extracción acuosa y se fraccionó con (NH4)2SO4 saturado a 20 %, 50 % y 80 %. Posteriormente, se seleccionaron las fracciones obtenidas con (NH4)2SO4 saturado a 50 % y 80 % por su alta actividad proteolítica, se concentraron por ultrafiltración con membranas de corte de peso molecular de 100 kDa, y se analizaron por electroforesis en geles de poliacrilamida con dodecil sulfato de sodio (SDS-PAGE). La actividad proteolítica del extracto crudo fue significativamente mayor (19.7-20.3 U / mg) a pH 2, 5, y 7 (P < 0.001). Las fracciones obtenidas con (NH4)2SO4 saturado a 20 %, 50 % y 80 % presentaron actividades proteolíticas óptimas a pH 5 (2.8 U / mg) y pH 6 (2.2 U / mg); pH 6 (4.3 U / mg) y pH 3-4 (3.6 - 3.7 U / mg); pH 3 (10.8 U / mg) y pH 10 (10.6 U / mg); respectivamente. Las subfracciones con peso molecular < 100 kDa obtenidas con (NH4)2SO4 saturado a 50 % y 80 % tuvieron máxima actividad proteolítica a pH alcalino. La subfracción < 100 kDa, obtenida con (NH4)2SO4 saturado a 80 % tuvo la mayor actividad proteolítica (37.3-43.7 U / mg) a pH 8-10, factor de purificación de 3 y 19.1 % de recuperación. Trece proteínas entre 9.8 a 104.8 kDa se identificaron en el extracto proteolítico crudo. Las proteínas de 31 - 33 y 39 - 41 kDa tuvieron la concentración más alta en las fracciones estudiadas, sugiriendo la posible predominancia de serín y aspartil proteasas, respectivamente. Nosotros sugerimos que la presencia de proteasas con máxima actividad a pH alcalino está relacionada con la adaptación de C. carpio a aguas contaminadas con pH alto. Aunque estos peces son inadecuados para el consumo humano, pueden ser empleados como materia prima para la producción de proteasas destinadas para varias industrias, incluido el tratamiento de aguas residuales.

AbstractCommon carp (Cyprinus carpio) is an aquatic organism of commercial value able to survive in polluted environments; carps contain proteolytic enzymes of physiological importance and potential industrial application. The objective of this work was partially purify and study the proteolytic activity at different pH of carp proteases living in a polluted environment. Three carps were captured in different zones of Zumpango polluted lagoon (Mexico) at 1 m of maximum deep. Protease crude extracts were obtained from dorsal muscle by aqueous extraction and fractionated by 20 %, 50 %, 80 %-saturated (NH4)2SO4. Fractions extracted with 50 % and 80 %-saturated (NH4)2SO4 were selected for their high proteolytic activity and concentrated by ultrafiltration through 100 kDa molecular weight cutoff membranes and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The crude proteolytic extract had significantly higher activity (19.7 - 20.3 U / mg) at pH 2, 5, and 7 (P < 0.001). Fractions obtained with 20 %, 50 % and 80 % - saturated (NH4)2SO4 showed peak activity at pH 5 (2.8 U / mg) and pH 6 (2.2 U / mg); pH 6 (4.3 U / mg) and pH 3 - 4 (3.6 - 3.7 U / mg); pH 3 (10.8 U / mg) and pH 10 (10.6 U / mg); respectively. Subfractions of < 100 kDa, obtained with 50 % and 80 %-saturated (NH4)2SO4, had peak proteolytic activity at alkaline pH. A < 100 kDa fraction, obtained with 80 %-saturated (NH4)2SO4, had the highest proteolytic activity (37.3 - 43.7 U / mg) at pH 8 - 10, purification factor of 3 and 19.1 % recovery. Thirteen proteins between 9.8 to 104.8 kDa were identified in the crude extract. Peak protein concentration was observed for 31 - 33 and 39 - 41 kDa, suggesting the possibility predominance of serine- and aspartyl- proteases, respectively. We suggest this protease with maximum activity at alkaline pH is related to the adaptation of C. carpio to polluted waters with high pH. Although unsuitable for human consumption, these organisms can be a source of protease production aimed to several uses as in the industry and waste water treatment among others.

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The contamination of water with arsenic has aroused concern around the world due to its toxic effects. Thus, the development of low-cost technologies for treating water contaminated with toxic metals is highly advisable. Adsorption is an attractive technology for purification of contaminated water, but it only transfers the contaminant from water to the solid adsorbent, which provokes another problem related to solid residue disposal. In this work, we developed a sustainable method for purifying water contaminated with arsenic by using δ-FeOOH nanoparticles. The adsorption capacities of nanomaterial for As3+ and As5+ species were 40 and 41 mg g-1, respectively, and were highly efficient to purify arsenic-contaminated water from a Brazilian river. The concentration of arsenic in water was close to zero after the water treatment by δ-FeOOH. Once the arsenic is adsorbed, it can be recovered by treatment with NaOH solutions. Approximately 85 % of the total adsorbed arsenic could be recovered and used as a precursor to produce useful material (Ag3AsO4) with excellent photocatalytic activity. It was active under visible light and had a high recyclability for oxidation of rhodamine B. Finally, the simple method described is promising to design sustainable process of environmental remediation with minimum residue generation.

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