Estudio comparativo de los métodos para la recuperación de cromo proveniente de los lodos de la planta de tratamiento de aguas residuales de la Empresa Curtiduría Serrano.

Abstract

The objective of this research was to carry out a comparative study of methods in order to recover the chromium in the sludge from wastewater treatment plant of Serrano Tannery Company which is located in Ambato canton, due to these sludge contains a high chromium content. The hysicochemical analysis shows a chromium concentration of 15050.647 mg/Kg, this situation causes an environmental problem in its final disposal. The methods assessed to recover the chromium in the sludge were: leaching, calcination/dilution. The first method was to acidify the sludge with concentrated sulfuric acid until the pH 2.5 has been reached and thus obtain the basic sulfate of chromium III. The second method was to calcine the sludge to 250 degrees centigrade and then to dissolve with dilute sulphuric acid to 10% until a pH 2.5 has been reached and in the same wayto obtain the basic sulfate of chromium III. With leaching method it was obtained a dark reencoloured liqueur with a chromium concentration of 7315.776 mg/L, while with the calcination/dilution method it was obtained a blue-green coloured liqueur with a chromium concentration of 9693.396 mg/L. It is concluded that the form of sludge (calcined or wet) has great influence on the results due to the sludge to be calcined removes all amount of water and part of organic matter so that adding acid, this reacts directly with chromium. The financial analysis shows that the leaching method is the most feasible to recover the chromium in the sludge from wastewater treatment plant thanks to the methodology used is simple, economic and ecologic.