Person:
Alvarado Martínez, Andrés Omar

Birth Date

1976-09-14

ORCID

0000-0002-9125-1221

Scopus Author ID

7006162056

Afiliación

Universidad de Cuenca, Cuenca, Ecuador
Universidad de Cuenca, Departamento de Recursos Hídricos y Ciencias Ambientales, Cuenca, Ecuador
Universidad de Cuenca, Facultad de Ingeniería, Cuenca, Ecuador

País

Ecuador

Organizational Units

Organizational Unit

Facultad de Ingeniería

La Facultad de Ingeniería, a inicios de los años 60, mediante resolución del Honorable Consejo Universitario, se formalizó la Facultad de Ingeniería de la Universidad de Cuenca, conformada por las escuelas de Ingeniería Civil y Topografía. Esta nueva estructura permitió una mayor especialización y fortalecimiento en áreas clave para el desarrollo regional. Cuenta con programas académicos reconocidos internacionalmente, que promueven y lideran actividades de investigación. Aplica un modelo educativo centrado en el estudiante y con procesos de mejora continua. Establece como prioridad una educación integra, la formación humanística es parte del programa de estudios que complementa a la sólida preparación científico-técnica. Las actividades culturales pertenecen a un programa permanente y activo al interior de nuestras dependencias, a la par de proyectos que desde el alumnado y bajo la supervisión de docentes cumplen con servicios de apoyo a nivel local y regional; promoviendo así una vinculación estrecha con la comunidad.

Job Title

Profesor (T)

Last Name

Alvarado Martínez

First Name

Andrés Omar

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Now showing 1 - 10 of 20

Exploring the influence of meteorological conditions on the performance of a waste stabilization pond at high altitude with structural equation modeling
(2018) Ho, Long; Van Echelpoel, Wout; Alvarado Martínez, Andrés Omar
Algal photosynthesis plays a key role in the removal mechanisms of waste stabilization ponds (WSPs), which is indicated in the variations of three parameters, dissolved oxygen, pH, and chlorophyll a. These variations can be considerably affected by extreme climatic conditions at high altitude. To investigate these effects, three sampling campaigns were conducted in a high-altitude WSP in Cuenca (Ecuador). From the collected data, the first application of structure equation modeling (SEM) on a pond system was fitted to analyze the influence of high-altitude characteristics on pond performance, especially on the three indicators. Noticeably, air temperature appeared as the highest influencing factors as low temperature at high altitude can greatly decrease the growth rate of microorganisms. Strong wind and large diurnal variations of temperature, 7–20 C, enhanced flow efficiency by improving mixing inside the ponds. Intense solar radiation brought both advantages and disadvantages as it boosted oxygen level during the day but promoted algal overgrowth causing oxygen depletion during the night. From these findings, the authors proposed insightful recommendations for future design, monitoring, and operation of high-altitude WSPs. Moreover, we also recommended SEM to pond engineers as an effective tool for better simulation of such complex system like WSPs.
Resistance analysis of morphologies in headwater mountain streams
(2021) Cedillo Galarza, Juan Sebastián; Sánchez Cordero, Esteban Remigio; Timbe Castro, Luis Manuel; Samaniego Alvarado, Esteban Patricio; Alvarado Martínez, Andrés Omar
River flow velocity is determined by the energy available for flow motion and the energy fraction lost by flow resistance. We compared the performance of different equations for the Darcy-Weisbach resistance coefficient (f ) and empirical equations to predict flow velocity. The set of equations was tested using data from the Quinuas headwater mountain river in the Andean region. The data was collected in three Cascades, two Step-pools, and one Plane-bed covering a wide range of velocity magnitudes. The results reveal that nondimensional hydraulic geometry equations (NDHG) with a Nash-Sutcliffe efficiency index (EF) varying from 0.6–0.85 provide the most accurate velocity prediction. Furthermore, the study proposes a methodology applicable to all morphologies for defining the NDHG parameters using easily measured field data. The results show an improvement in predictability with EF values in the range of 0.81–0.86. Moreover, the methodology was tested against data from the literature, which was not divided into morphologies providing EF values of around 0.9. The authors encourage the application of the presented methodology to other reaches to obtain additional data about the NDHG parameters. Our findings suggest that those parameters could be related to reach characteristics (e.g., certain characteristic grain size), and in that case, the methodology could be useful in ungauged streams. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Model based analysis of the growth kinetics of microalgal species residing in a waste stabilization pond
(2017) Decostere, Bjorge; Alvarado Martínez, Andrés Omar; Sanchez Merchan, Esteban Andres; Pauta Calle, Gladys Guillermina; Rousseau, Diederik; Nopens, Ingmar; Van hulle, Stijn W.h
BACKGROUND: In this study the growth kinetics of Chlorella and Scenedesmus, isolated from a Waste Stabilization Pond were investigated under different conditions of light intensity and temperature. Experimental data were collected by means of a combined respirometric and titrimetric set-up and used to extend a mathematical model. RESULTS: The experimental results illustrated the interdependent relationship of light intensity and temperature, which had a significant influence on the microalgal growth. Consequently, a previously developed model was extended with a mathematical function that describes this relationship. The maximum specific growth rate and oxygen mass transfer coefficient were considered for model calibration. The optimized parameter values for Chlorella were μmax = 0.56 ± 0.0008 d−1 and KLa = 10.02 ± 0.02 d−1. For Scenedesmus, the optimized parameter values were μmax = 0.19 ± 0.0004 and KL a = 7.71 ± 0.004 d−1. The model with optimized parameter settings described the dissolved oxygen production (derived from the respirometric data) and the related proton consumption (derived from the titrimetric data) reasonably well for both microalgal species. The threshold value for Theil's Inequality Coefficient of 0.3 was never exceeded. In addition, model validation for both species was performed indicating good correspondence between model prediction and experimental values. CONCLUSIONS: Based on the experimental observations, a previously developed mathematical model was extended with a function that describes the interaction between light intensity and temperature. After model calibration a difference in maximum specific growth rate between the two microalgal species was observed. This might be explained by differences in cell metabolism. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry
Treatment of faecal sludge from septic tanks using First Stage of French Vertical Flow Constructed Wetlands
(IWA. The international water asociation, 2022) Arevalo Durazno, Maria Belen; García Zumalacarregui, Jorge Alejandro; Alvarado Martínez, Andrés Omar; Tuan Ho, Long; Narvaez Torres, Andrea Carolina
Mostly disposed into the environment without any treatment, faecal sludge from septic tanks remains a critical environmental issue in major developing countries. Despite being considered an efficient natural solution for sludge treatment, Vertical Flow Constructed Wetlands have uncommonly been applied to deal with this issue. In this study, we investigated the performance of the First Stage of French Vertical Flow Constructed Wetlands as a practicable alternative for septic tank sludge treatment in the Andean region. From the results obtained during the first six months of operation, satisfactory removal efficiencies of over 40 % for COD and TS were obtained in a pilot scale. Appearing important for organic matter mineralization, high aeration capacity was maintained as showed in the DO concentrations measured in the influent and effluent, i.e. 0.33 mg.L-1 and 2.8 mg.L-1, despite the sludge load.
Hydrodynamic evaluation of five influent distribution systems in a cylindrical UASB reactor using CFD simulations
(2021) Cisneros Ramos, Juan Fernando; Cobos Cobos, Fabiola Estefania; Peláez Samaniego, Manuel Raúl; Nopens, Ingmar; Alvarado Martínez, Andrés Omar
UASB reactors are a promising option for environmentally friendly wastewater treatment due to their reduced carbon footprint and their capacity to treat a variety of wastewater strengths, among other recognized advantages over alternative wastewater treatment systems. The Influent Distribution System (IDS) is a critical structure for generating granules in a UASB reactor since it provides the required flow hydrodynamics for their formation. Thus, the objective of this study was to evaluate and compare the efficiency of five IDS configurations to generate ideal granulation conditions using Computational Fluid Dynamics (CFD) simulations. The IDS configurations were as follows: (C1) single radial inflow, (C2) upward axial inflow, (C3) downward distributed axial inflow, and two novel configurations in the form of (C4) double opposite radial inflow and (C5) downward tangential inflow. The hydrodynamic response of configuration C1 was validated in a physical model with dynamic Froude similitude. The granulation measurement was velocity-based in the reactor reaction zone using steady-state CFD simulations. The novel IDS configuration C4 was the one that resulted in the highest granulation volume, with up to 45.5% of the potential granulation volume of the UASB reactor, in contrast to the IDS C2 that obtained the lowest granulation with only 10.8%. Results confirm that the IDS directly impacts the hydrodynamics of the reactor and that model-based design can be used to ascertain IDS configurations that better promote granulation in UASB reactors
Algal community analysis in a waste stabilisation pond
(ELSEVIER, 2014-12-01) Alvarado Martínez, Andrés Omar
Our knowledge on the algal community structure in waste stabilisation ponds is limited and it is unclear how physical-chemical changes affect the algal community structure and the treatment performance of waste stabilisation ponds. In the present paper we studied the spatial distribution of the algal community in a waste stabilisation pond in Cuenca (Ecuador) and found that the distribution was associated with the BOD concentration of the system. At the upstream end of the facultative pond where the BOD value is relatively high (74mgL-1), the community is dominated by motile algal species such as Euglena and Cryptophytes. More downstream, the algal community is more evenly distributed (G=0.26>0.18) and also non-motile species such as Chlorophytes and Chrysophytes are present. Throughout the ponds, the reduction of motile algal species was associated with the decrease in BOD concentration. The dominance of Chlorophyta, Chrysophyta and Euglenophyta was highly associated with BOD concentration. Furthermore, it was concluded that the algal abundance (45541cellsmL-1), diversity (D=0.85), evenness (G=0.26) and richness (20.97) of the community in the maturation pond were higher than those of the facultative pond. The results of this research are valuable for a better understanding of the algae-based processes in waste stabilisation ponds.
Comparación de las eficiencias de recuperación de lípidos de las microalgas Chlorella y Scenedesmus obtenidas con diferentes disolventes
(2018) Pauta Calle, Gladys Guillermina; León Tamariz, Fabián; Cisneros Ramos, Juan Fernando; Pinos Vélez, Verónica Patricia; Alvarado Martínez, Andrés Omar
The lipids of microalgae are the source for obtaining third-generation biofuels so that fossil fuels canbe replaced. The objectives of this study were to determine the composition of the lipids of Chlorella and Scenedesmus microalgae using the gravimetric method; Determine the efficiency of different solvents for the extraction of lipids with the Soxhlet method and compare the lipid recovery productivities of Chlorella microalgae with thermal and physical pretreatments. The highest amount of lipids, 20.37% per dry sample, the microalga, the chlorella, the solvent mixture, the chloroform:methanol in a 1:2 ratio. The increase in the amount of lipids generated with the use of pretreatments no justifies its use for which it is recommended that no pretreatment be applied. The results allow to establish a baseline in the use of microalgae cultivable in the Ecuadorian mountain to obtain lipids for biofuels
Development of an automated tracer testing system for UASB laboratory-scale reactors
(2021) Cisneros Ramos, Juan Fernando; Nopens, Ingmar; Pinos Vélez, Verónica Patricia; Peláez Samaniego, Manuel Raúl; Alvarado Martínez, Andrés Omar
Residence time distribution (RTD) curves play an essential role in the hydraulic characterization of reactors. Current approaches for obtaining RTD curves in laboratory-scale reactors are time-consuming and subject to large errors. Thus, automated systems to obtain RTD curves in laboratory-scale reactors are of great interest for reducing experimental errors due to human interaction, minimizing experimentation costs, and continuously obtaining experimental data. An automated system for obtaining RTD curves in laboratory-scale reactors was designed, built, and tested in this work. During the tests conducted in a cylindrical upflow anaerobic sludge blanket (UASB) reactor, the system worked properly using the stimulus–response pulse technique with sodium chloride as a tracer. Four main factors were found to affect the representativeness of the RTD curves: flow stabilization time, test water conductivity, temperature, and surface tension. A discussion on these factors and the corresponding solutions is presented. The RTD curves of the UASB reactor are left-skewed with a typical tank reactor’s flow shape with channeling and dead zones. A transitory flow behavior was evidenced in the reactor, which indicates the influence of internal turbulent flow structures. The system proposed herein is expected to help study the hydraulics of reactors using laboratory-scale models more efficiently
Differences Between Effective and Physical Roughness Parameter- A Headwater Mountain River Experiment
(IEEE, 2021) Cedillo Galarza, Juan Sebastian; Alvarado Martínez, Andrés Omar; Narea Cardenas, Katherine Estefania; Sánchez Cordero, Esteban Remigio; Timbe Castro, Luis Manuel; Samaniego Alvarado, Esteban Patricio
One-dimensional hydrodynamic models (HM) are widely used in the hydraulic modeling of rivers and channels. The result obtained with this type of model depends largely on correct estimation the roughness parameter. The value of the roughness parameter obtained through a HM calibration process differs from the one measured in the field. Hence, the objective of this research is focused on identifying the difference between physical and effective roughness for different morphologies present in Mountain Rivers. Physical roughness was indirectly measured with field data and Manning equation, while Effective roughness was found through GLUE experiments using water depth as validation data in one dimensional models in HEC RAS. Physical and effective roughness coefficients have shown differences depending on the morphology. In Cascade and Step-pool the physical roughness is higher than effective roughness, while in Plane-bed effective roughness is higher than physical roughness. The differences are attributed to the deviations that occur between the real conditions and the flow idealizations in an 1D - HD model. For any modelling application is important to research roughness values used previously and avoid formulations or tables which are based on field measurements.
CFD analysis of sludge accumulation and hydraulic performance of a waste stabilization pond
(2012) Alvarado Martínez, Andrés Omar; Sánchez Cordero, Esteban Remigio; Durazno, Galo; Vesvikar, Mehul; Nopens, Ingmar
Sludge management in waste stabilization ponds (WSPs) is essential for safeguarding the system performance. Sludge accumulation patterns in WSPs are strongly influenced by the pond hydrodynamics. CFD modeling was applied to study the relation between velocity profiles and sludge deposition during 10 years of operation of the Ucubamba WSP in Cuenca (Ecuador). One tracer experiment was performed and three sludge accumulation scenarios based on bathymetric surveys were simulated. A residence time distribution (RTD) analysis illustrated the decrease of residence times due to sludge deposition. Sludge accumulation rates were calculated. The influence of flow pattern on the sludge deposition was studied, enabling better planning of future pond operation and desludging. © IWA Publishing 2012.