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Steel mill dust (SMD), produced by electric arc furnaces, is a highly polluting industrial waste due to its high content of metals (Zn, Fe, and Pb) and fine particle size (ca. 5.4 µm). This residue can be valorized to recover Zn using pyro and hydrometallurgical methods, with hydrometallurgy offering greater selectivity and lower energy costs. However, composition of SMD presents a challenge in identifying an optimal leaching agent. This study investigates the preferential extraction of Zn using two leaching agents, namely 150 g L−1 (1.5 M) phosphoric acid (H3PO4) and 240 g L−1 (6 M) sodium hydroxide (NaOH), in a two-stage leaching process (80 °C). Metallic Zn from the alkaline pregnant solution was recovered by electrodeposition (750 A/m2, graphite anode, stainless-steel cathode) and smelting (450 °C). The samples of SMD contained 26.3% Zn, 20.1% Fe, and 0.9% Pb, in compounds such as magnetite (Fe3O4), zincite (ZnO), and franklinite (ZnFe2O4). Each leaching agent successfully attained a 99% Zn recovery, demonstrating the proposed procedure’s high efficacy. However, H3PO4 leached also Fe and corroded the cathode during electrodeposition, thereby restricting the final recovery of metallic Zn. NaOH demonstrated greater selectivity for Zn over Fe and Pb, producing high-purity Zn deposits on the cathode by electrodeposition and 99% metallic zinc by smelting.

Nowadays, deep eutectic solvents (DESs) are seen as environmentally friendly alternatives with the potential to replace traditional solvents used in hydrometallurgical processes. Although DESs have been successfully applied in the recovery of metals from secondary sources, there is still innovative potential regarding DESs as green leaching agents applied in the recovery of metals from primary sources like polysulfide ores. This study aimed to evaluate the characteristics of DESs as solvents for some of the main metals present in typical polymetallic concentrates, like Cu, Fe, Pb, and Zn. Thus, three DESs based on choline chloride (ChCl) were prepared: 1:2 ChCl-urea (also known as reline), 1:2 ChCl-ethylene glycol (also known as ethaline), and 1:2 ChCl-glycerol (also known as glyceline). Then, dissolution tests at 30 °C were carried out with these DESs and different metal- (Cu, Fe, Pb, and Zn) bearing compounds (sulfates, oxides, and sulfides). According to the dissolution tests, it was found that the solubility of the studied metals (expressed as g of metal per Kg of DES) was dictated by the bearing species, reaching the dissolution of the metals from sulfates with values as high as two orders of magnitude higher than the metal solubility values for metal oxides and sulfides.

In this study, we address the ecological challenges posed by automotive battery recycling, a process notorious for its environmental impact due to the buildup of hazardous waste like foundry slag. We propose a relatively cheap and safe solution for lead removal and recovery from samples of this type of slag. The analysis of TCLP extracts revealed non-compliance with international regulations, showing lead concentrations of up to 5.4% primarily in the form of anglesite (PbSO4), as detected by XRF/XRD. We employed deep eutectic solvents (DES) as leaching agents known for their biodegradability and safety in hydrometallurgical processing. Five operational variables were systematically evaluated: sample type, solvent, concentration, temperature, and time. Using a solvent composed of choline chloride and glycerin in a 2:1 molar ratio, we achieved 95% lead dissolution from acidic samples at 90 °C, with agitation at 470 rpm, a pulp concentration of 5%, and a 5 h duration. Furthermore, we successfully recovered 55% of the lead in an optimized solution using an electrowinning cell. This research demonstrates the ability of DES to decontaminate slag, enabling compliance with regulations, the recovery of valuable metals, and new possibilities for the remaining material.

One of the main sources of activated carbon is biomass which can be transformed into char by pyrolysis. Apart from the obtaining coal, the pyrolysis of biomass can be used for the preparation of fuels, and this is why it is very important to determine its kinetic parameters for modelling. In the present research, the pyrolysis enthalpy of palm nut shells (Elaeis guineensis) was determined with the use of a differential scanning calorimetry study (DSC). To determine the kinetic parameters, the Not Reacted Core model was employed. This model considers that there is a heat and mass gradient between the furnace atmosphere and the interface formed during pyrolysis. To obtain the required data for the model, palm nut shells were submitted to pyrolysis in a Nichols furnace under reducing atmosphere. Samples were taken every 10 minutes to calculate char conversion. The experimental pyrolysis enthalpy resulted to be 301.81 J/g and then the monomeric units of cellulose, hemicellulose, and lignin were employed in order to determine the pyrolysis enthalpy per mole. The three biopolymers react with different mechanisms at different temperatures. The molecular weight resulted to be 172.38 g/mole, and the enthalpy for pyrolysis was 52.03 kJ/mol. For the application of the Not Reacted Core model, the amorphous char heat transfer coefficient was selected, and the value is 1.6 J/s·m·K. The reaction rate constant was 6.64 × 10−9 1/s assuming a first-order reaction, whereas the effective diffusion across the char layer was 4.83 × 10−7 m2/s.

Thiosulfate leaching combined with ion-exchange resins is an innovative alternative for gold recovery. According to the properties of activated carbon, it could replace resins in the gold recovery process, improve efficiency, and reduce operating cost. In this research, the adsorption process of gold thiosulfate complex on thiol-modified activated carbon was studied. Thioglycolic acid (ATG) was impregnated in activated carbon, and its adsorption ability was tested with synthetic solutions of gold and sodium thiosulfate (Au 10 mg·L−1, Na2S2O3 0.1 mol·L−1, pH = 10.0). Carbon was characterized by infrared spectroscopy, SEM-EDS, PZC titration, hardness number measures, and proximal analysis. Synthetic solutions were also characterized by UV-vis spectroscopy and cyclic voltammetry. The percentage of volatile material increased from 10.0 to 13.9% due to the impregnation process of ATG. Infrared spectra show characteristic bands of C-H, S-H, and C-S bonds. In the adsorption tests, the ATG-impregnated carbon achieved 91% of gold recovery, while the same amount of ATG in the liquid phase stirred with unmodified activated carbon reached 90% of gold recovery. The 44.9% of gold recovered with activated carbon impregnated with ATG was eluted with sodium cyanide ([NaCN] = 0.2 mol·L−1; [NaOH] = 0.25 mol·L−1; [CH3CH2OH] = 30% V/V; pH = 12.0; t = 24 h). These results suggest the gold transferred from the thiosulfate complex to a new gold thiolate complex.

Carbon reactivation is a strategy to reduce waste and cost in many industrial processes, for example, effluent treatment, food industry, and hydrometallurgy. In this work, the effect of physical and chemical reactivation of granular activated carbon (AC) was studied. Spent activated carbon (SAC) was obtained from a carbon in pulp (CIP) leaching process for gold extraction. Chemical and physical reactivations were evaluated using several acid-wash procedures (HCl, HNO3, H2SO4) and thermal treatment (650–950 °C) methods, respectively. The effect of the reactivation processes on the mechanical properties was evaluated determining ball pan hardness and normal abrasion in pulp resistance. The effect on the adsorptive properties was evaluated via the iodine number, the gold adsorption value (k expressed in mg Au/g AC), and Brunauer–Emmett–Teller (BET) surface area. Initial characterization of the SAC showed an iodine number of 734 mg I2/g AC, a k value of 1.37 mg Au/g AC, and a BET surface area of 869 m2/g. The best reactivation results of the SAC were achieved via acid washing with HNO3 at 20% v/v and 50 °C over 30 min, and a subsequent thermal reactivation at 850 °C over 1 h. The final reactivated carbon had an iodine number of 1199 mg I2/g AC, a k value of 14.9 mg Au/g AC, and a BET surface area of 1079 m²/g. Acid wash prior to thermal treatment was critical to reactivate the SAC. The reactivation process had a minor impact (

Nowadays, mining effluents have several contaminants that produce great damage to the environment, cyanide chief among them. Ferrites synthesized from transition metals have oxidative properties that can be used for cyanide oxidation due to their low solubility. In this study, cobalt and copper ferrites were synthesized via the precipitation method, using cobalt nitrate, copper nitrate, and iron nitrate as precursors in a molar ratio of Co or Cu:Fe = 1:2 and NaOH as the precipitating agent. The synthesized ferrites were impregnated in specific areas on active carbon. These composites were characterized using X-Ray Diffraction (XRD) and Scanning Electron Spectroscopy (SEM). The XRD results revealed a cubic spinel structure of ferrites with a single phase of cobalt ferrite and two phases (copper ferrite and copper oxides) for copper. The CoFe2O4 impregnated on active carbon reached a cyanide oxidation of 98% after 8 h of agitation; the composite could be recycled five times with an 18% decrease in the catalytic activity. In cobalt ferrites, a greater dissolution of iron than cobalt was obtained. In the case of copper ferrite, however, the copper dissolution was higher. These results confirm that ferrites and activated carbon composites are a novel alternative for cyanide treatment in mining effluents.

Waste electrical and electronic equipment (WEEE) has increased in recent decades due to the continuous advancement of technology in the modern world. These residues have various metals that are found in concentrations that make their recovery profitable. A group of metals of interest are the rare earths such as europium and yttrium, as well as semiconductors such as indium. Yttrium was recovered from cathode ray tubes that were manually dismantled. The resulted powder was leached with HNO3, and then the solution was submitted to solvent extraction with di-(2-ethylhexyl) phosphoric acid (DEHPA) using n-heptane as a diluent. For re-extraction, HNO3 was used again, and yttrium was precipitated by adding four times the stoichiometric amount of oxalic acid, reaching 68% yttrium purity. Indium was recovered from the liquid crystal display (LCD) screens for which the pulverized material was leached with H2SO4. Then, the indium sulfate was subjected to solvent extraction using DEHPA as an extractant, and diesel as a diluent. The re-extraction was carried out again with H2SO4, and the obtained acid solution was evaporated until the indium precipitated, reaching a recovery of 95%. The investigations that were carried out show that it is feasible to recover these metals in the form of oxides or phosphates with high commercial value.

The influence of the carbonization conditions of palm kernel in the hardnessof the produced char was established. attrition process was tested with differentchars evaluating the increase of hardness and carbon loss. active carbon-phe-nolic or epoxy resins composites were produced by impregnation and polyme-rization of resins on active carbon surface. an attritioned active carbon andphenolic resins composites with 99% hardness are obtained. such productscan adsorb a 100% of the soluble gold cyanide complex in the cyanidation -carbon in pulp (ciP) process, tested with a gold sulfide ore (9 g/ton au, 19%pyrite, 75% quartz) from the Portovelo deposit, Ecuador.

Se establece la influencia de las condiciones de carbonización de cuesco de palmiste, respecto a la dureza del carbón producido. Se ensaya el proceso de atrición por medio del incremento en dureza y pérdida de carbón. Se producen compósitos carbón activado-resina fenólica o epóxica por impregnación y po- limerización de las resinas en la superficie del carbón activado. Se obtiene carbón activado atricionado y compósitos con resinas fenólicas que tienen 99 % de dureza y que adsorben el 100% del complejo cianurado de oro soluble en un proceso cianuración - carbón en pulpa (ciP) ensayado con un mineral sulfurado aurífero (9 g/ton au, 19% pirita, 75% cuarzo) del yacimiento de Portovelo, Ecuador.

Resumen: En esta investigación se redujo la concentración de cromo presente en efluentes líquidos de la industria de curtiembre de 5000 mg/L (pH 3.6) hasta niveles inferiores a los establecidos por la normativa ambiental ecuatoriana (0.5 mg/L). Se emplearon tratamientos primarios convencionales como precipitación química y adsorción con carbón activado y como tratamiento secundario rizofiltración. Para la precipitación química del cromo como hidróxido a pH 8, se utilizaron diferentes álcalis como agentes precipitantes, con este procedimiento se redujo el 90% de la concentración de cromo inicial. Un 40% del cromo remanente se eliminó tratando el efluente con carbón activado, reduciendo el pH a valores entre 6 y 7. Previo a la aplicación de la rizofiltración se seleccionó la especie que presente mayor porcentaje de absorción de cromo, utilizando soluciones sintéticas y empleando plantas de alfalfa, acelga, pasto y sambo cultivadas por medios hidropónicos. Finalmente se aplicó la rizofiltración con plantas de sambo a efluentes de curtiembre previamente tratados con una concentración de cromo menor a 10 mg/L y pH 6.4. Para reducir esta concentración a valores menores de 0.5 mg/L se emplearon 20 plantas de sambo en un período de 20 días. Abstract: The concentration of chromium present in liquid effluents from tannery industries was reduced from 5000mg/L (pH 3.6) to lower levels than those established by the Ecuadorian environmental regulations (0.5mg/L). Conventional primary treatments (chemical precipitation and adsorption by activated charcoal) and rhizofiltration as secondary treatment were used. Chemical precipitation of chromium as hydroxide at pH 8 was performed using different alkalis (precipitating agent) and 90% of the initial chromium concentration was reduced. Approximately 40% of the remaining chromium was removed by treating the effluent with activated carbon which reduced the pH to a range of 6–7. Previous to the implementation of the rhizofiltration, the specie with the highest percentage of chromium absorption was selected testing synthetic chromium’s solutions and hydroponic cultivated alfalfa, chard, grass and sambo. Finally rhizofiltration with sambo plants was applied to pre-treated tannery effluents (chromium’s concentration below 10 mg/L and pH 6.4). To reduce this concentration to values bellow 0.5 mg/L, 20 plants of sambo were used for a 20 d period.

Resumen: La electrocoagulación es una operación que desestabiliza una emulsión y permite altos porcentajes de remoción de demanda química de oxígeno (DQO) y turbiedad. En el presente trabajo se evaluó la electrocoagulación como técnica de tratamiento no convencional de un efluente generado por una empresa de mantenimiento de motores y para la evaluación de la operación se midieron los parámetros: DQO, tensoactivos, sólidos suspendidos y totales, turbiedad y concentración de aluminio, cobre y cinc. El efluente estudiado se caracterizó por ser altamente heterogéneo, así la DQO varió entre 10 500 y 14 700mg/L. La turbiedad desde 619 NTU a 886 NTU. El rango de tensoactivos desde 86.6 mg/L a 221.6 mg/L. La concentración inicial de aluminio fue 87.9 mg/L, de cobre fue 123.5 mg/L y de cinc fue 13.2 mg/L. La concentración inicial de sólidos suspendidos fue 340 mg/L y la concentración de sólidos totales fue 10456 mg/L. En la investigación se establecieron los valores de las variables que influyen en la electrocoagulación para hacerla eficiente. El pH de operación que presenta mejores resultados es 9.7. La intensidad de corriente que se determinó como la más eficiente es de 1.8 A. Con esta intensidad de corriente se tiene una remoción de DQO de 32 %, remoción de sólidos suspendidos de 98.3 %, remoción de turbiedad de 97.4% y remoción de aluminio 88 %, de cobre 87% y de cinc de 99%, El tiempo de residencia que requiere la operación es de 60 min. Abstract: Electrocoagulation which is an unconventional operation to destabilize an emulsion and allows high removal of chemical oxygen demand (COD) and turbidity was studied. The technique was used to treat waste water generated by an engine maintenance company. The evaluation of operation was performed measuring the following parameters: COD, surfactants, total and suspended solids, turbidity and concentration of aluminum, copper and zinc. The effluent studied was highly heterogeneous, and the COD that varied from 10500 mg/L to 14700 mg/L, turbidity ranging from 619 NTU to 886 NTU and surfactants from 86.6 mg/L to 221.6 mg/L. The initial concentration of aluminum, copper and zinc were 87.9mg/L, 123.5mg/L and 13.20mg/L, respectively. The concentrations of suspended and total solids were 340 mg/L and 10456 mg/L, respectively. The investigation established the values of the variables that influence the electrocoagulation to make it efficient. The pH for maximum removals was 9.7 and the most efficient current intensity was 1.8 A. Using a current intensity of 1.8 A, the results were 32.0% COD removal, 98.3% suspended solids removal, 97.4% turbidity removal, 88.7% aluminum removal, 87.7% copper removal and 99.9% zinc removal. The residence time required for the operation is 60 min.

La electrocoagulación es una operación que desestabiliza una emulsión y permite altos porcentajes de remoción de demanda química de oxígeno (DQO) y turbiedad. En el presente trabajo se evaluó la electrocoagulación como técnica de tratamiento no convencional de efluentes generados por empresas de Mantenimiento de motores y para la evaluación de la operación se midieron los parámetros: DQO, tensoactivos, sólidos suspendidos y totales, turbiedad y concentración de aluminio, cobre y cinc. El efluente estudiado se caracterizó por ser altamente heterogéneo, así la DQO varió entre 10 500 mg/l y 14 700 mg/l. La turbiedad desde 619 NTU a 886 NTU. El rango de tensoactivos desde 86,6 mg/l a 221, 6 mg/l. La concentración inicial de aluminio fue 88 mg/l, de cobre fue 123 mg/l y de cinc fue 13 mg/l. La concentración inicial de sólidos suspendidos fue 340 mg/l y la concentración de sólidos totales fue 10 456 mg/l. En la investigación se establecieron los valores de las variables que influyen en la electrocoagulación para hacerla eficiente. El pH de operación que presenta mejores resultados es 9,7. La intensidad de corriente que se determinó como la más eficiente es de 1,8 A. Con esta intensidad de corriente se tiene una remoción de DQO de 32%, remoción de sólidos suspendidos de 98,3 %, remoción de turbiedad de 97,4 % y remoción de aluminio 88%, de cobre 87% y de cinc de 99%, El tiempo de residencia que requiere la operación es de 60 minutos.

Resumen.- En este trabajo se buscó modificar térmicamente arcillas tipo caolines para mejorar sus propiedades mecánicasnaturales y obtener materiales con posibilidades de uso industrial. Para ello se caracterizaron física-química y mineralógicamente caolines naturales y modificados, se estandarizaron métodos de análisis cualitativo de arcillas mediante difracción de rayos X (DRX), empleando técnicas comola dispersión-centrifugación y el ultrasonido, para la elaboración de placas de agregados orientados de muestrasde caolines. Además se cuantificaron las fases minerales presentes con la ayuda de programas especializados para DRX: TOPAS y SIROQUANT.Los caolines fueron modificados térmicamente a temperaturas entre 400 y 900 C, en periodos de tiempo de 1a 3 h, para producir metacaolín (material puzolánico). En función de las propiedades obtenidas, se definieron los campos de aplicación del los materiales en la industria cerámica y de confinamiento de residuos sólidos. Abstract.- The improvement of the natural mechanical properties of kaolin clays using temperature was studied to obtainmaterials with potential for industrial use. The natural and modified clays were characterized physically, chemicallyand mineralogically. Qualitative methods using X-Ray diffraction (XRD) were standardized using techniquessuch as dispersion-centrifugation and ultrasound in order to prepare oriented aggregate plates of kaolin samples.Additionally, the mineral phases were quantified with specialized software for XRD: TOPAS and SIROQUANT.The kaolin samples were thermally modified at temperatures between 400–900 C during periods of 1 to 3 h toproduce metakaolin (puzolanic material). The industrial application fields (ceramic and solid waste confinement)were defined according to their properties.

Resumen.- Se desarrolló carbón activado modificado (CAM) por la presencia de cobre metálico y sales de cobre (CuSO4,CuCl2, Cu(NO3)2) impregnadas en su estructura microporosa con una superficie específica de 600 m2/g. Se estudió la influencia del ion cúprico y del cobre metálico en la oxidación del ion cianuro con aire y CAM mediantesoluciones sintéticas de cianuro de sodio, en lechos fluidizados agitados, utilizando 80 g/L de CAM, a pH de 10.5y 190 N L/h de aire. Se logró oxidar el 99% de ion cianuro en 180 min, pudiéndose reutilizar el CAM por varias veces. Ensayos realizados con el CAM y efluentes industriales del proceso de cianuración-carbón en pulpa de mineralespolisulfurados, presentaron la oxidación del 99.5% de cianuro libre, incrementando 26 veces la velocidaddel proceso. Abstract.- Modified active carbon (CAM) was developed by impregnation of metallic copper and copper salts (CuSO4,CuCl2, Cu(NO3)2) on the microporous structure of an activated carbon (600m2/g of specific surface). The influenceof the cupric ion and the metallic copper on the oxidation of the cyanide ion with air and CAM was studied usingsynthetic solutions of sodium cyanide in fluidized bed reactors employing 80 g/L CAM, pH = 10.5 and 190N L/hof air. An oxidation of 99.0% of the cyanide ion was achieved after 180 min. CAM was reused several times forfurther procedures. Different tests were run using CAM and industrial effluents from processes of cyanidationcarbonin pulp of polysulfide minerals that showed an oxidation of free cyanide of 99.5 %, thus, increasing 26 timesthe oxidation process velocity.

Resumen: La extracción de oro a partir de minerales polisulfurados mediante soluciones amoniacales de tiosulfato de sodio y la presencia de iones cúpricos es una alternativa no tóxica a la cianuración. Por esta razón se realizó una comparación entre la cianuración y la lixiviación con soluciones amoniacales de tiosulfato para determinar la efectividad de ambos métodos. En la cianuración se obtuvo una recuperación de oro del 80.6 % después de 24 horas de agitación mientras que en la lixiviación con tiosulfato se consiguió el 80.9 % de recuperación de oro en una hora. Los lixiviados obtenidos fueron sometidos a cinco técnicas con el fin de extraer el oro contenido en dichas soluciones. La técnica más exitosa fue flotación iónica cuya recuperación de oro fue del 84 %. Posteriormente se realizó la electrólisis del concentrado de flotación iónica (espuma) a un voltaje de 1.5 V durante 3 horas lo que permitió alcanzar una recuperación de oro del 82 %. Abstract: Gold extraction from polysulphide ores by ammmoniacal thiosulfate solutions in presence of cupric ions is a non-toxic alternative to cyanidation. For that reason, a comparison between cyanidation and ammoniacal thiosulfate leaching was performed to verify the effectiveness of both methods. With cyanidation, a gold recovery of 80.6 % was accomplished at 24 hours, whereas with ammoniacal thiosulfate leaching process a 80.9 % of gold recovery was achieved at just one hour of agitation. The ammoniacal thiosulfate solutions obtained were treated with five different techniques in order to extract gold from the mentioned solutions. The most successful technique was ion flotation which gold recovery ascended to 84 %. Then electrowinning, applied to ionic flotation concentrate, was developed with 1.50 V during three hours obtaining 82 % of gold recovery.

Resumen: Se estudió la detoxificación de efluentes cianurados, mediante oxidación con dióxido de azufre (SO2), aire y catalizadores de Cu. Se ensayaron diversas especies de Cu tales como: CuSO4 en solución, carbón activado granular (CAG) impregnado con CuSO4, CAG impregnado con Cu0 y Cu0 granular. Este proceso es conocido como INCO, el cual oxida el cianuro WAD a cianato y precipita los metales tales como Cu, Ni, Zn, Cd y Fe. Se realizaron ensayos a escala de laboratorio con soluciones sintéticas de 500 mg/L NaCN y efluentes cianurados industriales. Se midió la variación de CN- con respecto al tiempo por titulación con AgNO3. Se estudió la influencia del pH, la dosificación de Na2S2O5 (fuente de SO2) y las concentraciones de los diferentes catalizadores. Los tiempos de oxidación del 98% de CN- de las soluciones sintéticas de NaCN, bajo las mejores condiciones de operación del proceso INCO (pH 10.0; 276 N L/h aire; 400 RPM; y 1000 mg/L Na2S2O5) fueron 210 min con 50 mg/L Cu2+ (CuSO4), 40 min con 50 g/L de CAG impregnado con CuSO4, 8 min con 50 g/L de CAG impregnado con Cu0 y 195 min con 10 g/L Cu0 granular. Los efluentes industriales fueron detoxificados utilizando 5 g/L CAG impregnado con Cu0. Estos efluentes, con concentraciones iniciales de 432.50 mg/L y 112.50 mg/L de cianuro total alcanzaron 0.06 mg/L cianuro total en 90 min y 0.05 mg/L cianuro total en 40 min, respectivamente. El contenido de metales en los efluentes (Cu, Cd, Zn, Ni y Fe) luego de la precipitación llegaron a los límites permisibles de descarga a un cuerpo de agua dulce según lo establecido en el TULAS. El precio del tratamiento de efluentes cianurados por el método INCO con CAG impregnado con Cu0 es de 6.70 USD/m3. Abstract: It was studied the detoxification of cyanide effluents by oxidation with sulfur dioxide (SO2), air and copper catalyzer. The CuSO4 solution, granular activated carbon (GAC) impregnated with CuSO4, GAC impregnated with Cu0 and granular Cu0 were studied. This process is called INCO process and it oxidizes WAD cyanide to cyanate and precipitates metals such as Cu, Ni, Zn, Cd and Fe. Experiments were conducted at laboratory scale using synthetic solutions of 500 mg/L NaCN and industrial cyanide effluents. The variation of the CN- concentration in time was determined titrimetrically with AgNO3 solution. The influence of pH and the concentrations of Na2S2O5 (SO2 source of process) and Cu catalysts on the rate of the removal of CN- were estudied. The oxidation times of the 98 % of cyanide removal from the synthetic solutions of NaCN based on the best operation conditions (pH 10,0; 276 N L/h air; 400 RPM and 1000 mg/L Na2S2O5) were: 210 min (50 mg/L Cu2+ obtained from CuSO4), 40 min (50 g/L GAC impregnated with CuSO4), 80 min (5 g/L GAC impregnated with Cu0) and 195 min (10 g/L granular Cu0). The industrial effluents were detoxified using 5 g/L GAC impregnated with Cu0. These effluents with initial concentrations of 432.50 mg/L and 112.50 of total cyanide reached 0.06 mg/L total cyanide in 90 min and 0.05 mg/L total cyanide in 40 min, respectively. Besides, the metal content (Cu, Cd, Zn, Ni and Fe) of the industrial effluents after precipitation reached the permissible limits for discharges into a fresh body water according to TULAS. The price of cyanide wastewater treatment by the INCO method using GAC impregnated with carbon is 6.70 USD/m3.

Resumen: El presente trabajo aborda el diseño de un sistema de tratamiento de los lixiviados generados por la disposición no controlada de polvo de acería sobre suelo agrícola. Para esto, se colocaron 15 cm de polvo de acería sobre 50 cm de suelo en columnas de vidrio de 6 cm de diámetro y 75 cm de altura; los sistemas se irrigaron con flujos constantes de agua de 0.15 mL/h equivalentes a la precipitación promedio anual de la serranía ecuatoriana. A fin de evitar en efecto pared y garantizar una distribución uniforme del agua en toda la sección transversal, se colocó tela de lana de vidrio sobre el sólido. Los lixiviados generados se recolectaron cada tres días durante cuatro meses y se caracterizaron por espectrofotometría de absorción atómica, encontrándose que presentaban concentraciones de cromo mayores a 0.5 mg/L, límite especificado por el TULAS para las descargas líquidas a agua dulce. A continuación los efluentes se estabilizaron con cemento y cal en relaciones líquido/sólido de 0.4, 0.5 y 0.6, hallándose que las dos primeras entregan un producto que cumple con la humedad recomendada de 10 % para su confinamiento en rellenos sanitarios. Finalmente, con base en los resultados obtenidos, se diseñó un sistema de tratamiento de 2 m³ mensuales de líquido, proponiéndose el siguiente proceso: mezcla del lixiviado en relaciones líquido/sólido de 0.5 respecto al cemento y 2.0 respecto a la cal; moldeo y compactación de la mezcla; curado y secado de los bloques cada tres días; y transporte de los bloques al relleno sanitario. Para esto, se requiere una inversión inicial de US$ 38 782.00 y un capital de operación mensual de US$ 803.48. Abstract: This paper addresses the design of a treatment system for leachate generated by the uncontrolled disposal of steel dust on agricultural land. For the development of the methodology presented in this manuscript, columns of glass (6 cm diameter), where were placed 15 cm of steel dust on 50 cm of soil, were installed. The columns were irrigated with constant fluxes of water equivalents to the average precipitations of the Ecuadorian Highland region (0.15 mL/h). To avoid the “wall effect”, fiberglass (6 cm diameter, 0.8 mm thickness) was located on the solid in order to distribute the water uniformly throughout the transversal section. Leachates were collected every three days during four months and characterized by atomic absorption spectrophotometry. Thus, it was found that the effluents exceeded the maximum permitted concentration of chromium and arsenic in Ecuador for may be discharged into freshwater bodies. Subsequently, the effluent was stabilized with cement and lime in liquid/solid ratios of 0.4, 0.5 and 0.6; the liquid/solid ratios of 0.4 and 0.5 allow obtaining blocks that meet the recommended moisture to be confined in landfills (10 %). Finally, a treatment system of 2m³/month capacity was designed based on the results. Thereby, the following process was proposed: mixing of the leachate in liquid/solid ratios of 0.5 and 2.0 relative to cement and lime respectively, molding and compacting of the mixture, curing and drying of the blocks every three days and transportation of the blocks to the landfill. This system requires an initial investment of US$ 38 782.00 and an operating costs of US$ 803.48 monthly.

El presente trabajo aborda la evaluación de los procesos químicos y físicos desarrollados en suelo agrícola afectado por el depósito de polvo de acería. Para esto se procedió con ensayos en columna en tres unidades experimentales: 1) 50 cm de suelo, 2) 15 cm de polvo de acería sobre 50 cm de suelo, y 3) 15 cm de polvo de acería; los sistemas se irrigaron con flujos constantes de agua de 0.15 mL/h equivalentes a la precipitación anual de la serranía ecuatoriana. Los lixiviados generados se recolectaron cada tres días durante cuatro meses y se caracterizaron por espectrofotometría de absorción atómica, encontrándose que presentaban concentraciones de cromo mayores a 0.5 mg/L, límite especificado por el TULAS para las descargas líquidas a agua dulce. Finalizados los ensayos en columna, se caracterizó el suelo agrícola afectado y el polvo de acería, hallándose que el primero se enriquece en metales como cromo, hierro, cobre y níquel sin alcanzarse valores anómalos y que mantiene prácticamente constante su contenido de zinc debido a la interacción con el desecho. Adicionalmente se encontró que la deficiente aireación del suelo agrícola afectado impidió la solubilización de la fracción orgánica en el agua de percolación. De este modo se concluyó que la presencia del polvo de acería sobre suelo agrícola induce a la acumulación de metales pesados y de materia orgánica en el sistema. Abstract:This paper addresses the evaluation of chemical and physical processes in agricultural soil affected by steel dust. For the development of the methodology presented in this manuscript, glass columns (6 cm diameter),where were placed: 1) 50 cm of soil, 2) 15 cm of steel dust on 50 cm of soil, and 3) 15 cm of steel dust, were installed. The columns were irrigated with constant fluxes of water equivalents to the average precipitations of the Ecuadorian Highland region (0.15 mL/h). Leachates were collected every three days during four months and characterized by atomic absorption spectrophotometry. Thus, it was found that the effluents exceeded the maximum permitted chromium concentration in Ecuador for discharge into freshwater bodies (0.5 mg/L). Affected agricultural soil and steel dust were characterized finding that the concentrations of heavy metals in soil, such as chromium, iron, copper and nickel, increases without reaching anomalous values and that soil zinc content remains practically constant due to interaction with the scrap. Additionally, it was found that poor ventilation of affected agricultural soil prevented the solubilization of the organic fraction in water percolation. Hence, it was concluded that the presence of steel dust on agricultural soil induces the accumulation of heavy metals and organic matter in the system.

Resumen: En este trabajo se presenta la evaluación de la contaminación generada por la presencia de polvos de acería depositados directamente sobre un suelo agrícola y alternativas para su tratamiento. Con este fin para la obtención de los lixiviados se instalaron columnas de vidrio de 6 cm de diámetro, en las que se colocó una capa de 15 cm de polvo de acería sobre 50 cm de suelo. Las columnas se irrigaron con flujos constantes de 0.15 mL/h de agua para simular la precipitación promedio de la serranía ecuatoriana. Muestras de los lixiviados generados se recolectaron periódicamente durante cuatro meses para determinar la concentración de metales pesados, encontrándose que su contenido de cromo y arsénico superaba el límite máximo permitido por la normativa TULAS para su descarga a cuerpos de agua dulce. Posteriormente se evaluaron las siguientes alternativas de depuración del efluente: i) estabilización del lixiviado con cemento Portland y cal, ii) depuración mediante procesos combinados de fitorremediación y adsorción iii) recuperación de zinc con electrólisis previo al tratamiento del lixiviado con métodos convencionales. La evaluación económica preliminar de la aplicación de estos procesos resultó en costos de operación de US$ 401.74, 0,36 y 11.84 por metro cubico de lixiviado tratado, respectivamente. Abstract:This paper addresses the evaluation of the pollution generated by the presence of steel dust(consideredhazardouswasteClass I by theEPA)deposited directly on an agricultural soil and treatment alternatives for decontamination. For this purpose, in order to obtain leachates, glass columns (6 cm diameter), where were placed 15 cm of steel dust on 50 cm of soil, were installed. The columns were irrigated with constant fluxes of water equivalents to the average precipitations of the Ecuadorian Highland region (0.15 mL/h). Samples of the generated leachates were recollected weekly during four months to determinate the heavy metals content. Thereby, it was found that the effluentsexceeded the maximum permitted concentration of chromium and arsenic in Ecuador for may bedischarged into freshwater bodies. Afterwards, the following depuration methods of the obtained liquid were employed:i) stabilization of the polluted leachate with Portland cement and lime, ii) depuration of the contaminated liquid with a combination of the phytoremediation and adsorption processes, and iii) recuperation of attractive metals with electrolysis previous the leachate treatment for conventional methods.The preliminary economic evaluation of each procedure resulted in operating costs of $401.7, $0,4 and $11.8 respectivel

Resumen: El objetivo de este trabajo es diseñar un sistema de tratamiento para loslixiviados generados en el relleno sanitario El Inga, los cuales presentanelevados contenidos de DBO5 (3 000–4 000 mg/L), sólidos suspendidos (200 - 340mg/L), DQO (700–6 000 mg/L) y color (800 a 5 546 mg Pt-Co/L). Para estepropósito se emplea el proceso de electrocoagulación como tratamiento primario,con 8 electrodos de aluminio durante 20 min de operación, con una densidad decorriente de 53 A/m2. Como segundo tratamiento se usa la fitorremediaciónaplicada en un sistema de humedales de flujo subsuperficial vertical y laadsorción en carbón activado como tratamiento terciario. La combinación deestos procesos redujo el nivel de concentración de los contaminantes hastavalores aceptados por la ordenanza 213 del Municipio del Distrito Metropolitanode Quito (MDMQ) para descargas líquidas. Se trataron dos muestras procedentesdel vertedero, uno de lixiviado crudo y otro de lixiviado que había recibido tratamientosde lodos activados y bioreactores de membranas. En el primer caso, luego deelectrocoagulación del lixiviado crudo se alcanzaron altas remociones parasólidos suspendidos (78,6 %), DBO5 (73,5 %), DQO (40,4 %) y color (79,4 %). Enel sistema de humedales (2,5 L/día) los porcentajes de eliminación decontaminantes son de 13,2 %, 91,2 % y 65,4 % respectivamente. Se empleóadsorción en columnas empacadas de carbón activado para la remoción de color (70,7%). En el segundo caso se empleó la fitorremediación alcanzando porcentajes deremoción para los SS, DQO y color de 2,9 %, 56,8 %, 50,3 % respectivamente. Enla adsorción con carbón activado la concentración de los mismos parámetros disminuyóen un 85,9 %, 73,9 % y 92,7 % respectivamente. Abstract: The aim of this paper is to design a treatment system for leachate generated at El Inga landfill, which have high contents of BOD5 ( 3 000–4 000 mg/L), COD (700–6 000 mg/L) , suspended solids (200-340 mg/L) and color (800 to 5 546 mg Pt-Co/L). For this purpose, electrocoagulation process was used as the primary treatment with 8 aluminum electrodes during 20 min of operation, with a current density of 53 A/m2. Phytoremediation applied to a vertical subsurface flow wetland system as secondary treatment and adsorption on activated carbon as tertiary treatment. The combination of these processes reduced the level of pollutant to values ​​accepted by Ordinance 213 of the Municipio del Distrito Metropolitano de Quito (MDMQ) for liquid discharges. Two leachate samples were treated, a raw leachate and a leachate that had been processed with activated sludge treatment and membrane bioreactors. In raw leachate electrocoagulation process high removals were achieved for suspended solids (78,6 %), BOD5 (73,5 %), COD (40,4 %) and color (79,4 %). In wetland system (2,5 L/day) rates of contaminant removal are 13,2 %, 91,2 % and 65,4 % respectively. Adsorption was used in packed columns of activated carbon for removal of color with a value of 70,7 %. For detoxification of pretreated leachate in the landfill was used phytoremediation with removal percentages for SS, COD and color of 2,9 %, 56,8 %, 50,3 %, respectively. In adsorption with activated charcoal concentration decreased 85,9 %, 73,9 % and 92,7 % respectively.

Resumen: En el Ecuador se generan alrededor de 6 toneladas diarias de residuos de arcillas que se emplean en el proceso de decoloración de aceites vegetales comestibles. Ya que este material constituye un peligroso pasivo ambiental, se presenta a continuación una alternativa para su recuperación. Se partió de la caracterización física, química y mineralógica de las tierras de blanqueo. Se ensayaron dos métodos de regeneración: a) Extracción soxhlet con acetona y posterior calcinación a diferentes temperaturas (400 - 600 °C) y tiempos (30 - 180 min). b) Prensado hidráulico con placas a 75°C, 100 atm de presión y posterior lavado con vapor de agua saturado (1.5 bares) por 4 h. Las tierras de blanqueo analizadas están compuestas principalmente por montmorillonita, paligorskita, cuarzo y restos fósiles de estructura amorfa. Para la primera alternativa, la arcilla recuperada presentó una máxima eficiencia en el blanqueo de aceite de palma del 98%; mientras en el segundo caso se alcanzó un porcentaje de blanqueo del 80%. Adicionalmente se determinó el diagrama de flujo más adaptable a la industria aceitera para una planta de recuperación de arcillas usadas de 10 toneladas por día de capacidad. Se definieron los equipos requeridos y se obtuvo el análisis económico preliminar para la instalación del proyecto. Abstract: In Ecuador, 6 tons/day of waste clays are generated in the bleaching process of edible vegetable oil. Since, these residues are considered a hazardous environmental liability, it is presented an alternative to recovery them. First, physical, chemical and mineralogical characterization of these clays was done. Two regeneration methods were evaluated: a) Soxhlet extraction using acetone followed by calcination at different temperatures (400600°C) and times (30-180 min). b) Hydraulic pressing with plates at 75°C, 100 atm and washing with saturated steam (1.5 bars) for 4 h. Fuller’s earth are composed of montmorillonite, palygorskite, quartz and fossil remains of amorphous structure. In the first alternative, the recovery clay presented a maximum efficiency in palm oil’s bleaching of 98%. While in the second case, it was obtained a bleaching percent of 80%. It was also determined the most adaptable flow diagram for the vegetable oil industry. The capacity of the clay’s recovery plant was 10 tons/day. Equipment requirements were defined and economic analysis necessary to run the project was finally obtained.

Resumen: Los residuos sólidos de la minería artesanal, con elevado contenido de metales pesados, generalmente se disponen en precarias“relaveras” sin ninguna protección para los suelos vecinos. Para reducireste problema es necesario el desarrollo de técnicas de remediación “in situ” que no involucren costos excesivos para su implementación. En este trabajo se presenta al tratamiento electrocinético como una alternativa de depuración de suelos afectados por actividad minera. En este caso la aplicación de una diferencia de potencial y la inyección de soluciones humectantes en el suelo, movilizan a los metales pesados hacia los el ectrodos, depurando el material contaminado. En el presentetrabajo se evalúa la movilización de iones (Cu, Cr, Pb y Zn) por la aplicación de un campo eléctrico de 10 V, en tres tipos de materiales: a)matriz andesítica inerte, b) suelo contaminado artificialmente con metales pesados y c) relaves mineros. Para evaluar la eficiencia delmétodo de descontaminación se realizan ensayos variando el arreglode la celda (con y sin pozos) y el agente humectante (soluciones de sulfato de sodio, sulfato ferroso y ácido acético) hasta que el suelo tratado cumpla con la normativa ambiental vigente. El sistema piloto móvil propuesto contará básicamente con 3 arreglos de electrodos de grafito dispuestos en pozos (que serán enterrados en las relaveras),una fuente de poder y un sistema de distribución de los agentes humectantes.Abstract: The residual material of artisanal mining that contains dissolved heavy metals is placed in "pools". That “pools” doesn’t have insulation from surrounding soil. To reduce this problem it is necessary to develop an effective remediation technique that can be applied "in situ" in the tailings “pools”, without generating excessive costs. This work presents the electrokinetic treatment as a decontamination alternative of soil affected by mining. Electrical current added and a solution injected into the soil, are agents that mobilize heavy metal ions at the anode or the cathode. The work includes the study of the mobilization of ions (Cu, Cr, Pb and Zn) by applying an electric field of about 10 V in three kinds of materials: a) inert matrix type andesite, b) in artificially contaminated soils with heavy metals and c) tailings of Ecuadorian mining area. To evaluate the effectiveness of the removal method some essays were performed with different arrangements of the cell (wells and without wells) and wetting agents (sodium sulphate, ferrous sulphate and acetic acid solutions) until the treated soil meets current environmental regulations. The mobile system consists of 3 arrays of graphite electrodes placed in wells (buried directly in pools), a power distribution and piping to distribute wetting agents to the electrode wells.

La drepanocitosis es la anemia hemolítica determinada genéticamente más frecuente en el mundo. En Cuba, la frecuencia del estado de portador es del 3,08 % en la población general. La fisiopatología de la oclusión vascular es muy compleja; involucra la polimerización de la Hb S, las alteraciones de la membrana del hematíe, las moléculas de adhesión, las citocinas inflamatorias, los factores de la coagulación y lesiones del endotelio vascular. Las manifestaciones clínicas más frecuentes son: las crisis vasooclusivas dolorosas, el síndrome torácico agudo, la crisis de secuestro esplénico, la crisis aplástica, la necrosis aséptica de la cabeza del fémur y la úlcera maleolar. El cuadro clínico es muy variable: desde niños que mueren temprano en la vida hasta pacientes que alcanzan la sexta década de la vida. En el Instituto de Hematología e Inmunología existe un Programa de Atención Integral que incluye: seguimiento sistemático desde temprano en la vida en una consulta especializada, la administración de ácido fólico de forma permanente y de penicilina oral profiláctica los primeros 5 años de la vida; así como la educación del niño y de sus padres. Desde 1986 se realiza esplenectomía parcial en la crisis de secuestro esplénico con excelentes resultados. Entre 2004-2008 fallecieron solamente 16 enfermos en todo el país y en 397 adultos la sobrevida fue de 53 años en la anemia drepanocítica y de 58 en la hemoglobinopatía SC. Como resultado de este programa, en los últimos años la sobrevida ha aumentado, la calidad de vida del paciente ha mejorado y han disminuido los costos invertidos en el tratamiento de las complicaciones.Drepanocytosis is the hemolytic anemia more frequent genetically determined in the world. In Cuba, the frequency of carrier status is of 3,08% in general population. The pathophysiology of vascular occlusion is very complex; includes the polymerization of the Hb S, the alterations of red-blood cells, the adhesion molecules, the inflammatory cytokines, the coagulation factors and the lesions of the vascular endothelium. The more frequent clinical manifestations are: painful vaso-occlusive crises, the acute thoracic syndrome, the splenic sequestration crisis, the aplastic crisis, the aseptic necrosis of femur head and malleolar ulcer. The clinical picture is very variable: from children dying early in life up to patients achieve the sixth decade of life. In the Institute of Hematology and Immunology there is an Integral Care Program including: systematic follow-up from early in life in a specialized consultation, permanent administration of folic acid and of prophylactic oral penicillin during the first 5 years of age; as well as the child education and of parents. From 1986 it is carried out the partial splenectomy in crises of splenic sequestration with excellent results. Between 2004-2008 in all the country deceased only 16 patients and in 397 adults the survival rate was of 53 years in the drepanocythemia and of 58 in the SC hemoglobinopathy. As result of this program, in past years the survival has increased, the quality of life of patient improved and the costs spent in treatment of complications has decrease.