Chemical partitioning of metals in thermally treated sewage sludge

摘要

Anaerobically treated sludge form two wastewater treatment plants was found to contain significant amounts of heavy metals (Cr, Cu, Fe, Ni, Pb and Zn). The metal form distribution in the sludge samples found by the application of a sequential extraction procedure indicated that an important part of the metal content is carried by the organic and the reducible fractions. The sludge was thermally treated at two different temperature, 105 deg. C and 900 deg. C. By applying sequential analysis, it was found that most of the metal content was removed from the initial mobile phases to more stable ones and also significant amounts were transformed to the gaseous phase. Finally, in order to estimate the metal leachability of the sludge samples, before and after thermal treatment, the Generalized Acid Neutralization Capacity procedure was used.