Assessment of metallic mobile fraction bioavailable from different sewage sludge samples using leaching test

Abstract

Analysis of metallic mobile fraction from sewage sludge wastewater treatment plants provides very useful information about the possibility of metallic mobile forms to migrate on the environment. Therefore, determination of total metallic mobile fraction, refers not only to exchange fraction but also to bonded metals in sewage sludge structure which can usually be removed with strong extractants. Together with leaching test are provided informations about the bioavailability of toxic metals in normal environmental conditions. In this condition, for assessing the risk of pollution induced by metals it is necessary to evaluate both, total and mobile content available for environment. In this paper a leached extraction method according to SR EN ISO 12457:2003 standard, that uses an extraction procedure (sludge-solution 1 -1 0 (m/v), 24 h, 40 rpm) was applied. As, Cd, Co, Cr, Cu, Mo, Ni, Pb, Se and Zn were detected in extractible solution by ICP-EOS technique. The metals detected after leaching test were compared with the values imposed by the current legislation and function of the results obtained was indicated the possibility to storage the sludge as a non-hazardous waste or the opportunity to use it as a fertilizer in agriculture.