San Lorenzo de Esmeraldas, Ecuador
San Lorenzo de Esmeraldas, Ecuador

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Rubio D.,University of Cádiz | Rubio D.,Luis Vargas Torres Technical University | Casanueva J.F.,University of Cádiz | Nebot E.,University of Cádiz
Applied Thermal Engineering | Year: 2015

Biofouling is a complex and important problem in cooling systems using water from natural sources such as lakes, rivers and sea. The first stage of biofilm formation is the colonization and uncontrolled microbial growth on surfaces. The aim of this study was to evaluate and to compare the effectiveness of different antifouling treatments in a heat exchanger cooled by seawater. Two types of experiments were carried out. Firstly, by employing a pilot plant simulating an industrial heat exchanger, chlorination and its combination with other treatments (UV and copper ions) were tested and the formed fouling was monitored and quantified. Then, the disinfection effectiveness of biocides employed was checked on two marine bacteria in order to identify the antifouling action mechanism. The combination of chlorine and copper was the most effective strategy for mitigation of fouling growth. After 60 days of testing, the thermal resistance showed no significant increase and the total solids accumulated inside the test tube were reduced by 70% compared to control treatment. The effectiveness of chlorine-copper treatment against fouling is probably due to a combination of their synergic inactivation mechanisms under prolonged exposure times, such as those of fouling experiments (60 days). The effectiveness of antifouling treatment was not only affected by the concentration of chlorine in the cooling water, but also by the dosage pattern. A chlorine peak of 0.4 mg L-1 for 1 h a day over the concentration of control (0.12 mg L-1) was able to reduce the increment in Rf and the accumulation of solids by approximately 50%. The combined use of chlorine and copper as antifouling treatment can be recommended in specific cooling systems that use seawater. © 2015 Elsevier Ltd.


Salinas-Rodriguez E.,Autonomous University of the State of Hidalgo | Salinas-Rodriguez E.,Luis Vargas Torres Technical University | Hernandez-Avila J.,Autonomous University of the State of Hidalgo | Rivera-Landero I.,Autonomous University of the State of Hidalgo | And 4 more authors.
Hydrometallurgy | Year: 2016

Several years of mining in the Pachuca y Real del Monte mining district have led to the production of a great amount of mining tailings which is currently a great environmental problem. However, these residues contain metals of value and interest that cannot be recovered using harmful and aggressive reagents such as cyanide. Thiosulfate solutions represent a good alternative because of the advances made during the last few years of research on this subject. The kinetic study carried out indicates that the process involved in the leaching treatment of mining tailings for silver was only slightly affected by the stirring rate in the range studied; the reaction orders were 1 (oxygen partial pressure 0.2-1 atm), 0.074 (thiosulfate concentration 100-500 mol·m- 3), 0.455 (pH 4-12) and 0.26 (Copper concentration 50-300 mol·m- 3). The apparent activation energy of the process was 1.912 kJ·mol- 1 in the temperature range from 288 to 318 K. A change of control seemed to occur above 318 K, possibly due to the destabilization of oxygen in the inner portion of the solution at higher temperatures. According to the results, kinetic is controlled by a mass transfer of oxygen at the solid-liquid interface. In the presence of copper ions and oxygen, the reaction rate increases, so the process was carried out using a stoichiometric excess of oxygen. The process was applied to a mining tailing, containing both metallic and silver sulfides, having a similar behavior to that observed by previous authors using silver powder and silver plate. © 2015 Elsevier B.V. All rights reserved.


Garcia-Solares S.M.,National Polytechnic Institute of Mexico | Ordaz A.,Luis Vargas Torres Technical University | Monroy-Hermosillo O.,Metropolitan Autonomous University | Jan-Roblero J.,National Polytechnic Institute of Mexico | Guerrero-Barajas C.,National Polytechnic Institute of Mexico
Applied Biochemistry and Biotechnology | Year: 2014

Sulfidogenesis in reactors is mostly achieved through adaptation of predominantly methanogenic granular sludge to sulfidogenesis. In this work, an upflow anaerobic sludge blanket (UASB) reactor operated under sulfate-reducing conditions was inoculated with hydrothermal vent sediments to carry out sulfate reduction using volatile fatty acids (VFAs) as substrate and chemical oxygen demand (COD)/SO4 −2 ratios between 0.49 and 0.64. After a short period of adaptation, a robust non-granular sludge was capable of achieving high sulfate reduction efficiencies while avoiding competence with methanogens and toxicity to the microorganisms due to high sulfide concentration. The highest sulfide concentration (2,552 mg/L) was obtained with acetate/butyrate, and sulfate reduction efficiencies were up to 98 %. A mixture of acetate/butyrate, which produced a higher yielding of HS−, was preferred over acetate/propionate/butyrate since the consumption of COD was minimized during the process. Sludge was analyzed, and some of the microorganisms identified in the sludge belong to the genera Desulfobacterium, Marinobacter, and Clostridium. The tolerance of the sludge to sulfide may be attributed to the syntrophy among these microorganisms, some of which have been reported to tolerate high concentrations of sulfide. To the best of our knowledge, this is the first report on the analysis of the direct utilization of hydrothermal vent sediments as an alternate source of sludge for sulfate reduction under high sulfide concentrations. © 2014, Springer Science+Business Media New York.


Luis Vargas Torres Technical University | Entity website


Luis Vargas Torres Technical University | Entity website


Luis Vargas Torres Technical University | Entity website

ACTIVIDADES RECIENTES enero 6, 2016 


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AUTORIDADES abril 13, 2015  Para ver el perfil acadmico solo dele clic en la foto


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CONCURSO DE MRITOS Y OPOSICIN PARA DOCENTES TITULARES AUXILIARES DE LA UNIVERSIDAD TCNICA LUIS VARGAS TORRES DE ESMERALDAS La Universidad Tcnica Luis Vargas Torres de Esmeraldas, en cumplimiento a lo dispuesto en la Ley Orgnica de Educacin Superior en sus artculos: 150, 152 y al Reglamento Interno de Carrera y Escalafn del Profesor e Investigador, CONVOCA a Concurso Pblico de Merecimientos y Oposicin para llenar las vacantes de: PROFESORES TITULARES AUXILIARES, para las distintas carreras que oferta la UTE-LVT IMPORTANTE: Los requisitos mnimos son: Tener ttulo de posgrado de cuarto nivel (maestra o Ph.D) en el campo del conocimiento requerido y registrado en la SENESCYT ...


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BASES DE DATOS DIGITALES CON INFORMACIN CIENTFICA Las bases de datos digitales con informacin cientfica, siguen siendo actualmente la herramienta ms utilizada en lo que a investigacin acadmica se refiere, pues permite al investigador (estudiante, docente, cientfico) conseguir desde un esbozo general hasta una meticulosa definicin de muchos tpicos. Adems, ofrecen la excelente posibilidad de incluir audio, enlaces a otros sitios de Internet, grficos, videos e hipertexto ...


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