Rediseño del sistema de tratamiento de aguas residuales para la recuperación de cromo y oxidación de sulfuros en la Curtiembre Pieles Puma de la ciudad de Ambato.

Abstract

The wastewater treatment system was redesigned to reduce the sulphides of the hair water and to recover the chromium III from the water of the tanning process for its subsequent reuse. In this work, three stages were established: First stage, the characterization of the waters of the different processes, in which values outside the regulations are determined for wastewater such as: chemical oxygen demand, biochemical demand of oxygen and sulphides; for waters of the tanning process, out of standard parameters such as: chemical oxygen demand, biochemical oxygen demand and hexavalent chromium. Second stage; execution of the experimental coagulation-flocculation test, under the following conditions: concentration of aluminium polychloride (PAC) of 20 mg/L for tanning waters and 40 mg/L in waters of hair, with a pH of 9. It is then carried out sedimentation, aeration and filtration. Third stage; precipitation of Chromium III in the presence of sulfuric acid (1:10) with an approximate pH of 3. As a result, in scrub waters a removal percentage was obtained for: sulphides equal to 95,9%, chemical oxygen demand equal to 91,8%, oxygen biochemical demand equal to 99,3%, while for tanning waters removal percentages were obtained for: Total chromium equal to 99,8%, chemical oxygen demand equal to 79,5%, biochemical oxygen demand equal to 97,5%. With the recycled chromium III implemented in the tanning process at 30%, skins were obtained to which the following physical tests were carried out: Resistance to tension with averages of 1461,48 N/cm2; Elongation percentage, an average of 63,75%; Lastometry, average value of 9,52 mm. It was concluded that the recycled chromium in this percentage gave good physical properties to the leather. It is recommended to implement the wastewater treatment system, avoiding the discharge of contaminated water from the tanning and furling stages.