Context: The lack of dissolved oxygen (DO) in water bodies has become a serious problem for several ecosystems due to drastic changes in their climatic, biological, and physical conditions. The presence of microorganisms, organic matter, and clays, which are carried by landslides and rainwater, affect the process of restoration and transfer of DO in water, thus making it necessary to study how these factors affect the process of DO transfer in water bodies. Method: This work is focused on studying the influence of clays during the DO transfer process in water bodies. To this effect, samples of clays from the region of Paipa, Boyacá, were added in 1, 3 and 5% by weight into the samples of clean water. The aeration process was performed using a constant flow diffusion system. The tests were carried out until the saturation of dissolved oxygen in each of the water samples was obtained. Results: The results show that the presence of clays during the transfer of DO have little influence on bodies of water. However, variations were observed in time intervals of <5 min in which the increase in the percentage of clays favored the transfer of DO. Conclusions: With these results, it is concluded that the presence of clays can generate a beneficial effect during the transfer of DO in bodies of water with a high oxygen deficiency, whereas, for water samples with a relatively high percentage of DO, clays can hinder the DO restoration process.

Objetivo: Evaluar la tasa de transferencia de oxígeno disuelto (OD), en un aireador de superficie de baja velocidad (Low Speed Surface Aerator – LSSA), variando la potencia; y proponer una modificación geométrica de los impulsores, para mejorar la eficiencia de aireación estándar (Standar Aeration Efficiency - SAE). Metodología: Se modeló un LSSA a través de software CAD, y se construyeron 3 prototipos de LSSA, mediante un proceso de impresión 3D, modificando la geometría original del impulsor. Luego se realizaron ensayos a escala piloto, usando los LSSA acoplados a un motorreductor capaz de generar 210 RPM. Finalmente, se determinaron los coeficientes de transferencia de oxígeno, y la eficiencia de aireación en el agua, de los LSSA, por medio de un modelo matemático. Resultados: A partir de las proyecciones obtenidas, se estableció que la modificación geométrica propuesta, incrementa la SAE en un 20.3% y 29.8% para potencias de 1 y 2 vatios (W), respectivamente; manteniendo casi constante la tasa de transferencia estándar de oxígeno (Standar Oxygen Transfer Rate - SOTR); además, la forma geométrica y disposición de los impulsores propuesta, parece favorecer el tiempo de contacto entre la fase gaseosa (aire) y la fase liquida (agua), mejorando el tiempo de permanencia de las burbujas atrapadas, evidencia representada en los coeficientes kLa (h-1). Conclusiones: De acuerdo con los resultados, se puede inferir que estos aireadores de tipo LSSA, pueden ser optimizados con un diseño más eficiente, permitiendo reducir el consumo energético asociado a su funcionamiento, sin penalizar la transferencia de OD.

In this work, the effect of radon gas removal was studied for thermal water samples subjected to aeration and dissolved oxygen (DO) transfer processes. The prototype used in this work consisted of the application of a diffusion aeration system, usually used in water treatment processes, and the incorporation of a camera with the presence of LR-115 passive detectors, used for the measurement of radon gas. The Pylon ABC-6 active measurement method was used as a reference mechanism for radon gas concentration, while the dissolved oxygen measurement was measured simultaneously using a digital oximeter. The results obtained show that the DO transfer process is accompanied by an optimal removal of the radon gas present in the water samples, with a reception data of 1.5 ± 0.2 kBq·m-3, 61% of the value initially obtained. These data show that DO transfer processes have a great contribution to the removal of radon gas present in water bodies.

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Coal mining represents one of the primary economic incomes in the department of Boyacá, Colombia. However, the acid mine drainage (AMD) generated has a tremendous environmental impact in the area due to the presence of sulfate ions (SO4-2), heavy metals, and low pH This article studies the behavior in the content of Fe and sulfates in AMD samples when treated within an artificial anaerobic vertical flow wetland, analyzing the concentration of these elementsand the content of dissolved oxygen (DO) and pH at different time intervals. The treatment of a MAD from the department of Boyacá was carried out using a bioreactor prototype with an organic substrate to provide the necessary conditions for the development of sulfate-reducing bacteria. Measurements were made with hydraulic retention times between 24 to 120 hours, monitoring the changes in the content of total Fe, SO4-2, pH, and DO. The data obtained show a reduction for total Fe of 88.3%, established at 5.61g∙m-2∙day-1, and for SO4-2 of 34.3% with 9.35g∙m-2∙day-1; reaching a maximum removal degree of 52.32% at 120h for sulfates and 92% for Fe, where the maximum removal peak is achieved, reducing the Fe removal rate for longer times. The reduction in the concentration of Fe is related to the reduction of DO and regulation of the pH, in addition to favoring the reduction of sulfate ions through the formation of the mineralogical phases pyrite and siderite. These data show that the anoxic conditions of the organic environment are maintained, for which a subsequent aeration stage is suggested.

Influencia del ángulo y perímetro de impacto de las aspas en un aireador de eje horizontal sobre la transferencia de oxígeno disuelto Influence of the angle and perimeter of contact of the blades in a horizontal axis aerator on the transfer of dissolved oxygen

The reduction of dissolved oxygen (DO) in water is associated with the effect of climate change. The lack of oxygen in water bodies directly affects the biological species present in different shallow water bodies such as swamps and wetlands, as well as in aquaculture processes. An optimal value in the DO concentration favors the reproduction of these biological species present in both artificial and natural environments. For this, various equipment has been developed to favor the increase of DO in the water to acceptable values. However, some of these systems are expensive, energy inefficient, and noisy which generate adverse impacts in aquatic ecosystems due to perturbances in the water. This study measures the efficiency (KgO2·kWh-1) of introducing DO into the water using a paddle wheel aerator system at low RPMs destined for shallow bodies of water. Tests were performed on anoxic water samples using aerators with 6, 12, and 24 paddles at the laboratory level. By increasing the voltage (6, 9, and 12V), the RPMs applied to each device through a geared motor is also increased. The results show a higher DO transfer rate in the 1 and 5 mg of O2·L-1 range. The best configuration concerning energy consumption worked at low RPMs using the 6-paddle wheel aerator at 6V. This establishes that, in addition to the management of low revolutions, the use of a smaller number of wheels favors an increase in efficiency during the DO restoration process in shallow water bodies.

En este trabajo, se estudió y comparó dos procesos de biorremediación de lodos generados en estaciones de servicio y estaciones de venta de combustibles de la ciudad de Tunja-Boyacá, Colombia, los cuales están contaminados con hidrocarburos totales de petróleo (TPH). Las muestras de lodo se recolectaron en las trampas de grasas de las estaciones para ser tratadas mediante técnicas de bioestimulación y bioaumentación; comparar los resultados con una muestra de control para evaluar la eficiencia de los procesos. Las pruebas se realizaron durante 12 semanas, observando las variaciones de temperatura, pH, humedad y concentración final de TPH. Los resultados obtenidos indican que la técnica de bioaumentación presenta un mejor desempeño en la remoción de TPH, alcanzando una disminución del 75.4% en TPH. La técnica de bioestimulación presentó los resultados más bajos, alcanzando solo el 54,9% para el mismo período de tiempo evaluado. A partir de la proyección se establece que la técnica de bioaumentación tendría la capacidad de reducir los tiempos de tratamiento hasta en un 28,6% (6 semanas), lo que repercute a largo plazo en los costes y la implementación del tratamiento biológico. Estos resultados abren la posibilidad de implementar este tipo de tratamientos a escala real para gestionar este tipo de subproductos generados en el ámbito de la venta de combustibles por ser altamente tóxicos para el medio ambiente y la salud humana.