Treatment and Recovery Of Sludge Containing Heavy Metals

Abstract

This work presents the results of wastewater sludge treatment coming from a dismissed industrial site. Sludge sample was collected from an industrial site and treated with sulfuric acid to extract heavy metals (Cu, Ni, Cd and Zn) that are separated by electrodeposition. To determine the best extractive parameters we carried out a study on the effects of sulfuric acid concentration and solid to liquid ratio. To minimize power consumption during the electrodeposition, the cathode used was made in the same material as the extracted metal. In order to have deposition time as similar as possible, the cathode area used was adapted to the concentration of the respective metal. The recovery of each metal was made potentiostatically at different potentials. The results show that for 5g/L solid to liquid ratio more than 99,9% of heavy metals can be removed from the sludge by treating with 0,5M sulfuric acid in less than 2hours. The recovery of heavy metals by reduction was achieved at 99%. The solution, obtained after electrodeposition, contains metals concentrations in agreement with Algerian legislations.