Chemical and nano-mineralogical study for determining potential uses of legal Colombian gold mine sludge: Experimental evidence.

The present study is focused on the chemical and nano-mineralogical characterization of sludge from gold mine activities, in order to put forward diverse solution alternatives, where lack of knowledge has been found. The sample was collected from "La Estrella" mine of Suarez, located in Department of Cauca, south-west Colombia. The sludge micro-structure and chemical composition were analyzed using a high resolution transmission electron microscopy (HR-TEM) equipped with a dispersive X-ray detector (EDS). X-ray diffraction technique was employed to identify the mineralogical phases present in the sludge. Additional mineralogical characterization was done by using RAMAN spectroscopy. Main findings points to its potential to be used as a fertilizer, this is why, mine sludge contains macronutrients such as P, Ca and S, together with micronutrients like Cu. However, the presence of goethite could decrease the mobilization of nutrients to soils, thus additional alternatives, for instance, a mixture with humus or another material containing Humic Acids should be done, in order to minimizing its retention effect. Additionally, another possible uses to explore could be as construction and ceramic material or in the wastewater treatment for nutrient retention and organic material removal. Rutile (TiO2 nanoparticles) particles have been also detected, what could cause health concern due to its nanoparticle toxic character, mainly during gold extraction process.

Estudio de geotextiles para el tratamiento de efluentes del cultivo de Trucha Arcoíris (Oncorhynchus mykiss) / Study of geotextiles in the treatment of wastewater from farming rainbow trout (Oncorhynchus mykiss) / Estudo de geotêxtis para o tratamento de efluentes de cultivo de truta arco-íris (Oncorhynchus mykiss)

Resumen El proceso de producción piscícola genera dos tipos de efluentes; el primero de flujo continuo asociado a la operación normal de las granjas piscícolas y el segundo de flujo intermitente generado por labores de lavado de los estanques. Este último contiene la mayor concentración de contaminantes del proceso de cultivo. El presente estudio tuvo como objetivo evaluar a escala de laboratorio la filtración en geotextiles no tejidos como alternativa para el tratamiento del flujo proveniente del lavado de un estanque multipropósito (MULTIPRO) con cultivo de Trucha Arcoíris, específicamente se evaluó el comportamiento del geotextil frente a la eficiencia en la reducción de material en suspensión, nutrientes y materia orgánica, así como el desarrollo de la pérdida de carga. Se determinó que el empleo de geotextiles permite obtener eficiencias promedio en reducción de sólidos suspendidos totales (SST), demanda bioquímica de oxígeno (DBO), fósforo total (PT) y nitrógeno total Kjeldahl (NTK) de 98%, 68%, 62% y 79% respectivamente, operando a tasa de filtración de 3 m/h. Estas eficiencias son superiores a las reportadas por tecnologías de mayor costo que podrían presentar limitaciones de uso en la zona rural en Colombia. Se observó un rápido desarrollo de la pérdida de carga y consecuentemente una baja duración de la carrera de filtración, alcanzando valores promedio de 39 min, lo cual sugiere que el empleo de este tipo de filtros, en términos de duración de carrera se debe optimizar, de modo que permita un uso más extendido de los geotextiles y disminuya los costos de inversión asociados al recambio de las mismas.

Abstract The process of production of the fish farms generate two types of effluents: one with continuous flow during normal operation and the other an intermittent flow during cleaning operations. This last one has a lot higher solid concentration than the normal operation effluent. The present study was designed to assess at laboratory scale, the non woven geotextile filtration for the treatment of cleaning effluents from a MULTIPRO pond with rainbow trout (Oncorhynchus mykiss) culture. The efficiency in the reduction of suspended material, nutrients and organic matter was evaluated, as well as the development of the hydraulic head losses. It was determined that the filtration of these effluents through non woven geotextiles allows to obtain the following average removal efficiencies: total suspended Solids (98%), biochemical oxygen demand (68%), total phosphorus (62%) and total Kjeldahl nitrogen (79%) at filtration rate of 3 m/h. These efficiencies are comparable or even higher than those reported by higher-cost technologies, which would present limitations for rural use in Colombia. It was observed a rapid development of head loss and consequently low filter run duration with an average value of 39 min. This is suggesting that non woven geotextile filtration should be optimized en terms of filter run duration, so as to allow a more extended use of the blankets and to reduce the investment costs associated to the replacement of the same ones.

Resumo O processo de produção de peixes gera dois tipos de efluentes; o primeiro fluxo contínuo associado com a operação normal de explorações piscícolas e o segundo de fluxo intermitente, gerado pelo trabalho de lavagem dos tanques. Este último contém a maior concentração de contaminantes do processo de cultivo. O objetivo deste estudo foi avaliar em escala de laboratório a filtração em geotêxtis não tecido como uma alternativa para o tratamento do fluxo de um tanque de lavar multiuso (MULTIPRO) com cultivo de truta Arco-íris, especificamente avaliou-se o comportamento do geotêxtil contra a eficiência na redução do material em suspensão, nutrientes e matéria orgânica, bem como o desenvolvimento de perda de carga. Determinou-se que o uso de geotêxtil permite a obtenção de uma média na eficiência na redução de sólidos suspensos totais (SST), demanda bioquímico de oxigênio (DBO), total de fósforo (TP) e total nitrogênio Kjeldahl (TNK) de 98%, 68%, 62% e 79% respectivamente, operando com taxa de filtração de 3m/h, estas eficiências são superio res aos relatados por tecnologias de custo mais elevadas que podem apresentar limitações de utilização na área rural, na Colômbia. Reparou-se um desenvolvimento rápido da perda de carga e, consequentemente, uma baixa duração da carreira de filtração, atingindo valores médios de 39 min, o que sugere que o uso deste tipo de filtros, em termos de duração da carreira se deve aperfeiçoar, a fim que permita uma utilização mais generalizada de geotêxtis e reduza os custos de inves timento associados com a substituição do mesmo.