Removal of iron–cyanide complexes from wastewaters by combined UV–ozone and modified zeolite treatment
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2015
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1 Programa de Tecnologías de Tratamiento (PTT), Centro de Tecnología del Uso del Agua (CTUA), Instituto Nacional del Agua (INA), Au. Ezeiza-Cañuelas km.1.62 (1804), Buenos Aires, Argentina 2 Departamento de Química, Facultad de Ingeniería, Universidad de Buenos Aires (UBA) – INTECIN -Av. Paseo Colón 850 (1063), Buenos Aires, Argentin
Resumen
A treatment system was developed to remove iron-complexed cyanide from wastewaters discharged by small surface finishing workshops. Alkaline chlorination, a widely used treatment method, does not remove iron–cyanide complexes and produces chlorine secondary pollution effects. In this work, the effectiveness of a bench scale system with a UV–ozone step, followed by a fixed bed made of manganese modified natural zeolite was studied to remove potassium hexacyanoferrate(II) K4[Fe(CN)6]. The system was operated on a semi-continuous basis processing up to 7.2 l batches of synthetic wastewater. The optimal residence time was established by feeding the system with a free iron solution and using a residence time distribution (RTD) model.
With the employed experimental conditions, a 66% cyanide removal was observed at the UV–ozone stage. The fixed bed retained 55% of the total iron fed and an additional 5% of iron was precipitated. Cyanide removal was slightly increased by fixed bed up to 68%. This method achieved a significant removal of iron–cyanide complexes. The results were analysed by using an RTD model and a mechanism for the processes occurred was proposed. Technical and economical scaling up conditions must be studied in future works to assess the feasibility of treating wastewaters from small electroplating workshops.
Descripción
Fil: Hanela, Sergio. Instituto Nacional del Agua. Centro de Tecnología del Uso del Agua. Programa de Tecnologías de Tratamiento; Argentina.
Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Química; Argentina.
Fil: Durán, Jorge. Instituto Nacional del Agua. Centro de Tecnología del Uso del Agua. Programa de Tecnologías de Tratamiento; Argentina.
Fil: Jacobo, Silvia. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Química; Argentina.
Fil: Durán, Jorge. Instituto Nacional del Agua. Centro de Tecnología del Uso del Agua. Programa de Tecnologías de Tratamiento; Argentina.
Fil: Jacobo, Silvia. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Química; Argentina.