Applicability of computational fluid dynamics to simulate ozonation processes

AbstractThis paper presents an integrated mathematical model based on the principle of computational fluid dynamics along with the kinetics of ozone decay and microbial inactivation to predict the performance of ozone disinfection in fine bubble column contactors. The model can be represented using a mixture two-phase flow model to simulate the hydrodynamics of the water flow and using two transport equations to track the concentration profiles of ozone and microorganisms along the height of the column, respectively. The applicability of this model was then demonstrated by comparing the simulated ozone concentrations with experimental measurements obtained from a pilot scale fine bubble column. Excellent agreement was obtained in terms of the dissolved ozone and the degree of microorganism inactivation without any pre-assumption about flow backmixing or dispersion level. It was also confirmed that in some cases, the presence of dead space or short-circulation could greatly affect the effective contact time for the dinfection to occur. This suggests that the great opportunity may exist to improve the efficiency of ozonation contactors in practice. The future work of this investigation is to confirm the numerical prediction of inactivation contour diagrams.ResumenEste artículo presenta un novedoso modelo matemático que integra los principios de la dinámica de fluidos computacional, la cinética del ozono y las teorías de inactivación microbiana del ozono para pronosticar la desinfección del agua en columnas de burbujas. El modelo se describe mediante las ecuaciones de Navier- Stokes que caracterizan la hidrodinámica de la mezcla agua-aire y dos ecuaciones de transporte usadas para rastrear los micro-organismos y el ozono dentro de la columna de burbujas. La aplicabilidad del modelo fue demostrada comparando resultados numéricos obtenidos con el modelo contra datos experimentales obtenidos de ensayos realizados en una planta de ozono construida a escala piloto. Se obtuvo una excelente correlación en términos del ozono disuelto y el grado de inactivación de microorganismos sin la necesidad de asumir predeterminados patrones de recirculación del agua o de dispersión del ozono. También se pudo confirmar que en algunos casos, la presencia de zonas muertas o de recirculación podría afectar el tiempo de contacto efectivo para que la desinfección ocurra. Esto sugiere que existe una gran oportunidad, en la práctica, para mejorar la eficiencia de los reactores de desinfección del agua con ozono. La etapa siguiente de esta investigación es confirmar los pronósticos numéricos del modelo con contornos reales del proceso de inactivación

Simplified Mathematical Model for Computing Draining Operations in Pipelines of Undulating Profiles with Vacuum Air Valves

[EN] The draining operation involves the presence of entrapped air pockets, which are expanded during the phenomenon occurrence generating drops of sub-atmospheric pressure pulses. Vacuum air valves should inject enough air to prevent sub-atmospheric pressure conditions. Recently, this phenomenon has been studied by the authors with an inertial model, obtaining a complex formulation based on a system composed by algebraic-di erential equations. This research simplifies this complex formulation by neglecting the inertial term, thus the Bernoulli¿s equation can be used. Results show how the inertial model and the simplified mathematical model provide similar results of the evolution of main hydraulic and thermodynamic variables. The simplified mathematical model is also verified using experimental tests of air pocket pressure, water velocity, and position of the water column.Coronado-Hernández, ÓE.; Fuertes-Miquel, VS.; Quiñones-Bolaños, EE.; Gatica, G.; Coronado-Hernández, JR. (2020). Simplified Mathematical Model for Computing Draining Operations in Pipelines of Undulating Profiles with Vacuum Air Valves. Water. 12(9):1-12. https://doi.org/10.3390/w12092544S112129Fuertes-Miquel, V. S., Coronado-Hernández, O. E., Mora-Meliá, D., & Iglesias-Rey, P. L. (2019). Hydraulic modeling during filling and emptying processes in pressurized pipelines: a literature review. Urban Water Journal, 16(4), 299-311. doi:10.1080/1573062x.2019.1669188Fuertes-Miquel, V. S., Coronado-Hernández, O. E., Iglesias-Rey, P. L., & Mora-Meliá, D. (2018). Transient phenomena during the emptying process of a single pipe with water–air interaction. Journal of Hydraulic Research, 57(3), 318-326. doi:10.1080/00221686.2018.1492465Tijsseling, A. S., Hou, Q., Bozkuş, Z., & Laanearu, J. (2015). Improved One-Dimensional Models for Rapid Emptying and Filling of Pipelines. Journal of Pressure Vessel Technology, 138(3). doi:10.1115/1.4031508Coronado-Hernández, O. E., Fuertes-Miquel, V. S., Besharat, M., & Ramos, H. M. (2018). Subatmospheric pressure in a water draining pipeline with an air pocket. Urban Water Journal, 15(4), 346-352. doi:10.1080/1573062x.2018.1475578Ramezani, L., Karney, B., & Malekpour, A. (2016). Encouraging Effective Air Management in Water Pipelines: A Critical Review. Journal of Water Resources Planning and Management, 142(12), 04016055. doi:10.1061/(asce)wr.1943-5452.0000695Zhou, L., & Liu, D. (2013). Experimental investigation of entrapped air pocket in a partially full water pipe. Journal of Hydraulic Research, 51(4), 469-474. doi:10.1080/00221686.2013.785985Carlos, M., Arregui, F. J., Cabrera, E., & Palau, C. V. (2011). Understanding Air Release through Air Valves. Journal of Hydraulic Engineering, 137(4), 461-469. doi:10.1061/(asce)hy.1943-7900.0000324Bianchi, A., Mambretti, S., & Pianta, P. (2007). Practical Formulas for the Dimensioning of Air Valves. Journal of Hydraulic Engineering, 133(10), 1177-1180. doi:10.1061/(asce)0733-9429(2007)133:10(1177)Ramezani, L., Karney, B., & Malekpour, A. (2015). The Challenge of Air Valves: A Selective Critical Literature Review. Journal of Water Resources Planning and Management, 141(10), 04015017. doi:10.1061/(asce)wr.1943-5452.0000530Coronado-Hernández, O., Fuertes-Miquel, V., Besharat, M., & Ramos, H. (2017). Experimental and Numerical Analysis of a Water Emptying Pipeline Using Different Air Valves. Water, 9(2), 98. doi:10.3390/w9020098Laanearu, J., Annus, I., Koppel, T., Bergant, A., Vučković, S., Hou, Q., … van’t Westende, J. M. C. (2012). Emptying of Large-Scale Pipeline by Pressurized Air. Journal of Hydraulic Engineering, 138(12), 1090-1100. doi:10.1061/(asce)hy.1943-7900.0000631Coronado-Hernández, O. E., Fuertes-Miquel, V. S., Iglesias-Rey, P. L., & Martínez-Solano, F. J. (2018). Rigid Water Column Model for Simulating the Emptying Process in a Pipeline Using Pressurized Air. Journal of Hydraulic Engineering, 144(4), 06018004. doi:10.1061/(asce)hy.1943-7900.0001446Coronado-Hernández, O. E., Fuertes-Miquel, V. S., Iglesias-Rey, P. L., & Martínez-Solano, F. J. (2020). Closure to «Rigid Water Column Model for Simulating the Emptying Process in a Pipeline Using Pressurized Air» by Oscar E. Coronado-Hernández, Vicente S. Fuertes-Miquel, Pedro L. Iglesias-Rey, and Francisco J. Martínez-Solano. Journal of Hydraulic Engineering, 146(3), 07020002. doi:10.1061/(asce)hy.1943-7900.0001681Vasconcelos, J. G., & Wright, S. J. (2008). Rapid Flow Startup in Filled Horizontal Pipelines. Journal of Hydraulic Engineering, 134(7), 984-992. doi:10.1061/(asce)0733-9429(2008)134:7(984)Vasconcelos, J. G., Klaver, P. R., & Lautenbach, D. J. (2014). Flow regime transition simulation incorporating entrapped air pocket effects. Urban Water Journal, 12(6), 488-501. doi:10.1080/1573062x.2014.881892Wang, L., Wang, F., & Lei, X. (2018). Investigation on friction models for simulation of pipeline filling transients. Journal of Hydraulic Research, 56(6), 888-895. doi:10.1080/00221686.2018.1434693Malekpour, A., Karney, B. W., & Nault, J. (2016). Physical Understanding of Sudden Pressurization of Pipe Systems with Entrapped Air: Energy Auditing Approach. Journal of Hydraulic Engineering, 142(2), 04015044. doi:10.1061/(asce)hy.1943-7900.0001067Coronado-Hernández, Ó. E., Fuertes-Miquel, V. S., Mora-Meliá, D., & Salgueiro, Y. (2020). Quasi-static Flow Model for Predicting the Extreme Values of Air Pocket Pressure in Draining and Filling Operations in Single Water Installations. Water, 12(3), 664. doi:10.3390/w12030664Leon, A. S., Ghidaoui, M. S., Schmidt, A. R., & Garcia, M. H. (2010). A robust two-equation model for transient-mixed flows. Journal of Hydraulic Research, 48(1), 44-56. doi:10.1080/0022168090356591

Environmental and Health Benefits Assessment of Reducing PM2.5 Concentrations in Urban Areas in Developing Countries: Case Study Cartagena de Indias

High concentrations of particulate matter (PM) could significantly reduce the quality of useful life and human life expectancy. The origin, control, and management of the problem has made great steps in recent decades. However, the problem is still prominent in developing countries. In fact, often the number and spatial distribution of the air quality monitoring stations does not have an appropriate design, misleading decision makers. In the present research, an innovative assessment is proposed of the environmental, health and economic benefits corresponding to a 20% reduction in the PM2.5 concentration in the urban area of Cartagena de Indias, Colombia. Cases of mortality and morbidity attributable to fine particles (PM2.5) were estimated, with particular emphasis on mortality, emergency room visits and hospitalizations from respiratory diseases, in addition to their economic assessment using BenMAP-CE®. The novelty of using BenMAP-CE® in studying respiratory diseases and PM2.5 exposure in developing countries lies in its ability to provide a comprehensive assessment of the health impacts of air pollution in these regions. This approach can aid in the development of evidence-based policy and intervention strategies to mitigate the impact of air pollution on respiratory health. Several concentration-response (C-R) functions were implemented to find PM2.5 attributable mortality cases of ischemic heart and cardiopulmonary disease, lung cancer, respiratory and cardiovascular disease, as well as cases of morbidity episodes related to asthma exacerbation and emergency room/hospitalization care for respiratory disease. A 20% reduction would have avoided 104 cases of premature death among the population older than 30 in Cartagena, and around 65 cases of premature mortality without external causes

Analysis of PM2.5 and Meteorological Variables Using Enhanced Geospatial Techniques in Developing Countries: A Case Study of Cartagena de Indias City (Colombia)

The dispersion of air pollutants and the spatial representation of meteorological variables are subject to complex atmospheric local parameters. To reduce the impact of particulate matter (PM2.5) on human health, it is of great significance to know its concentration at high spatial resolution. In order to monitor its effects on an exposed population, geostatistical analysis offers great potential to obtain high-quality spatial representation mapping of PM2.5 and meteorological variables. The purpose of this study was to define the optimal spatial representation of PM2.5, relative humidity, temperature and wind speed in the urban district in Cartagena, Colombia. The lack of data due to the scarcity of stations called for an ad hoc methodology, which included the interpolation implementing an ordinary kriging (OK) model, which was fed by data obtained through the inverse distance weighting (IDW) model. To consider wind effects, empirical Bayesian kriging regression prediction (EBK) was implemented. The application of these interpolation methods clarified the areas across the city that exceed the recommended limits of PM2.5 concentrations (Zona Franca, Base Naval and Centro district), and described in a continuous way, on the surface, three main weather variables. Positive correlations were obtained for relative humidity (R2 of 0.47), wind speed (R2 of 0.59) and temperature (R2 of 0.64)

Spatiotemporal Analysis of PM2.5 Concentrations on the Incidence of Childhood Asthma in Developing Countries: Case Study of Cartagena de Indias, Colombia

The increase in airborne pollution in large cities since the mid-20th century has had a physiologically proven impact on respiratory health, resulting in the irritation and corrosion of the alveolar wall. One of the demographics of the population most affected by this problem is children. This study focuses on the relationship between particulate matter of 2.5 μm (PM2.5) and childhood asthma, which is one of the main respiratory diseases identified in developing countries. The city of Cartagena de Indias, Colombia, is taken as a case study. A relevant correlation between childhood asthma and PM2.5 is found. Incidence series of paediatric asthma on a monthly scale and PM2.5 records in the city of Cartagena are considered. As is common in developing countries, the series was incomplete due to a lack of experts and insufficient economical resources. Therefore, several statistical and analytical processes were applied to provide sufficient quality to the series. An improvement of the time scale of the records was carried out, as well as the completion (statistical imputation) of missing data due to low statistical significance, by applying Rstudio®, PAST® and SPSS®. The last phases consisted of the determination of the main factors that cause childhood asthma incidence, the estimation of the correlation between asthma incidence and PM2.5, as well as the estimation of health impact. A reduction in PM2.5 concentration was simulated using BenMap-CE software to reach safe levels according to the WHO guidelines on air quality to identify preventable cases of childhood asthma, as air pollution has been found to be related to this disease. In addition, a log-linear model was applied to determine the number of hospital visits avoided after reducing the levels of PM2.5 concentration to the maximum levels recommended by WHO. The results showed a good agreement between childhood asthma incidence and PM2.5 pollutants in the spectral analysis (75% coincidence) and Chi2 (85.5% of coincidence) assessments, while visual correlation, mean and linear regression showed lower relations (61.0%, 55.5% and 0.48%, respectively). A reduction to a safe level of 5 μg/m3 would lead to a reduction of 240 annual cases of childhood asthma (95% CI: 137–330)

Methodology for selecting atmospheric monitoring sitesin urban areas affected by emissions from mobile sources

El monitoreo atmosférico es una de las etapas fundamentales en la identificación de estrategias para minimizar, prevenir y controlar los impactos de la dispersión de contaminantes en el aire, sobre la salud pública y el ambiente. Por tanto, el objetivo principal de este articulo consiste en proponer una metodología para la selección de  sitios de monitoreo atmosférico en zonas urbanas afectadas por las emisiones de fuentes móviles. Primeramente se identificaron los sitios que presentaban mayor flujo vehicular y se priorizaron teniendo presente  los siguientes  criterios  de selección: seguridad, influencia de otras fuentes, facilidad del montaje de los equipos,  accesibilidad al sitio, identificación de barreras y obstáculos,  registro histórico de datos  y grado de concentración  usando el software CALINE 3.La modelación agrupo datos característicos de las vías, meteorológicos y de flujo vehicular de un año típico de la zona en estudio.   A cada uno de estos parámetros le es asignada una valoración cuantitativa, la cual define los sitios donde se realizará el monitoreo. Como resultados se desarrolló una guía para seleccionar los lugares en donde se puedan desarrollar campañas de monitoreo atmosférico asociadas a fuentes móviles. La metodología fue aplicada en la ciudad de Cartagena de Indias haciendo uso del modelo de calidad del aire CALINE3.Atmospheric monitoring is one of the fundamental steps in identifying strategies to minimize, prevent and control the impact of the dispersion of pollutants in the air, on public health and the environment. Therefore, the main objective of this article is to propose a methodology for selecting air monitoring sites in urban areas affected by emissions from mobile sources. First, the places with the highest vehicular flow were identified and prioritized according to the following selection criteria: safety, influence of other sources, ease of assembly of equipment, accessibility to the site, identification of barriers and obstacles, historical record of data and degree concentration of the pollutant: in this case carbon monoxide, using CALINE 3 software. The modeling grouped characteristic data related with roads, meteorology and vehicular flow of a typical year of the zone under study. A quantitative assessment is assigned to each of these parameters, which defines the sites where the monitoring will be performed. As a result, it was developed a guide to select those places where atmospheric monitoring campaigns related with mobile sources can be held. This methodology was applied in the city of Cartagena de Indias by using air quality model for assessment, CALINE

Methodology for selecting atmospheric monitoring sitesin urban areas affected by emissions from mobile sources

El monitoreo atmosférico es una de las etapas fundamentales en la identificación de estrategias para minimizar, prevenir y controlar los impactos de la dispersión de contaminantes en el aire, sobre la salud pública y el ambiente. Por tanto, el objetivo principal de este articulo consiste en proponer una metodología para la selección de  sitios de monitoreo atmosférico en zonas urbanas afectadas por las emisiones de fuentes móviles. Primeramente se identificaron los sitios que presentaban mayor flujo vehicular y se priorizaron teniendo presente  los siguientes  criterios  de selección: seguridad, influencia de otras fuentes, facilidad del montaje de los equipos,  accesibilidad al sitio, identificación de barreras y obstáculos,  registro histórico de datos  y grado de concentración  usando el software CALINE 3.La modelación agrupo datos característicos de las vías, meteorológicos y de flujo vehicular de un año típico de la zona en estudio.   A cada uno de estos parámetros le es asignada una valoración cuantitativa, la cual define los sitios donde se realizará el monitoreo. Como resultados se desarrolló una guía para seleccionar los lugares en donde se puedan desarrollar campañas de monitoreo atmosférico asociadas a fuentes móviles. La metodología fue aplicada en la ciudad de Cartagena de Indias haciendo uso del modelo de calidad del aire CALINE3.Atmospheric monitoring is one of the fundamental steps in identifying strategies to minimize, prevent and control the impact of the dispersion of pollutants in the air, on public health and the environment. Therefore, the main objective of this article is to propose a methodology for selecting air monitoring sites in urban areas affected by emissions from mobile sources. First, the places with the highest vehicular flow were identified and prioritized according to the following selection criteria: safety, influence of other sources, ease of assembly of equipment, accessibility to the site, identification of barriers and obstacles, historical record of data and degree concentration of the pollutant: in this case carbon monoxide, using CALINE 3 software. The modeling grouped characteristic data related with roads, meteorology and vehicular flow of a typical year of the zone under study. A quantitative assessment is assigned to each of these parameters, which defines the sites where the monitoring will be performed. As a result, it was developed a guide to select those places where atmospheric monitoring campaigns related with mobile sources can be held. This methodology was applied in the city of Cartagena de Indias by using air quality model for assessment, CALINE

Applicability of computational fluid dynamics to simulate ozonation processes

AbstractThis paper presents an integrated mathematical model based on the principle of computational fluid dynamics along with the kinetics of ozone decay and microbial inactivation to predict the performance of ozone disinfection in fine bubble column contactors. The model can be represented using a mixture two-phase flow model to simulate the hydrodynamics of the water flow and using two transport equations to track the concentration profiles of ozone and microorganisms along the height of the column, respectively. The applicability of this model was then demonstrated by comparing the simulated ozone concentrations with experimental measurements obtained from a pilot scale fine bubble column. Excellent agreement was obtained in terms of the dissolved ozone and the degree of microorganism inactivation without any pre-assumption about flow backmixing or dispersion level. It was also confirmed that in some cases, the presence of dead space or short-circulation could greatly affect the effective contact time for the dinfection to occur. This suggests that the great opportunity may exist to improve the efficiency of ozonation contactors in practice. The future work of this investigation is to confirm the numerical prediction of inactivation contour diagrams.ResumenEste artículo presenta un novedoso modelo matemático que integra los principios de la dinámica de fluidos computacional, la cinética del ozono y las teorías de inactivación microbiana del ozono para pronosticar la desinfección del agua en columnas de burbujas. El modelo se describe mediante las ecuaciones de Navier- Stokes que caracterizan la hidrodinámica de la mezcla agua-aire y dos ecuaciones de transporte usadas para rastrear los micro-organismos y el ozono dentro de la columna de burbujas. La aplicabilidad del modelo fue demostrada comparando resultados numéricos obtenidos con el modelo contra datos experimentales obtenidos de ensayos realizados en una planta de ozono construida a escala piloto. Se obtuvo una excelente correlación en términos del ozono disuelto y el grado de inactivación de microorganismos sin la necesidad de asumir predeterminados patrones de recirculación del agua o de dispersión del ozono. También se pudo confirmar que en algunos casos, la presencia de zonas muertas o de recirculación podría afectar el tiempo de contacto efectivo para que la desinfección ocurra. Esto sugiere que existe una gran oportunidad, en la práctica, para mejorar la eficiencia de los reactores de desinfección del agua con ozono. La etapa siguiente de esta investigación es confirmar los pronósticos numéricos del modelo con contornos reales del proceso de inactivación

Caracterización físico-química de aceites usados de motores para su reciclaje

This paper presents the physical-chemical evaluation of used engine oils from samples taken from industries that are located in Mamonal industrial sector in Cartagena de Indias. Among the characteristics taken into consideration it can be found: density, humidity percentage, viscosity, metals in suspension and high calorific value; some of the used methods were: densimetry, Karl fischer, viscosimetry, and atomic absorption. It can be highlighted that the analyzed samples didn’t report significant presence of tin, lead, chromium, silver and cadmium. The presence of calcium, magnesium, sodium, zinc and phosphorus can be due to additives added in order to improve their characteristics. The presence of chromium and iron in the samples is interpreted as a sign of wear in the parts. The presence of silicon can be provided by dust filtration. According to the above and proper treatment such oils are susceptible to recycle.En este trabajo se presenta la  caracterización físico-química de aceites usados de motor de una muestra de empresas del sector industrial de Mamonal de la ciudad de Cartagena de Indias, entre las características tenidas en cuenta estuvieron: densidad, porcentaje de humedad, viscosidad, metales en suspensión y  poder calorífico superior, algunos de los métodos utilizados fueron: densimetría, karlfischer, viscosimetría y absorción atómica. Se resalta que en las muestras analizadas no se reporta  una presencia significativa de estaño, plomo, cromo, plata y cadmio. La presencia de calcio, magnesio, sodio, zinc, fósforo puede ser producto de los aditivos que se emplean para mejorar sus características. La presencia de Cromo y Hierro en las muestras se interpreta como indicio de desgaste de piezas. El silicio encontrado puede ser aportado por filtración de polvo. Acorde con lo anterior y un adecuado tratamiento estos aceites son susceptibles de recicla