Production and Characterization of Adsorbent Materials from Sewage Sludge by Pyrolysis

The conventional sludge disposal options include landfill, application to farmland and forestry and incineration. However, since in the last decade sewage sludge and industrial sludge are being generated in increasing amounts due to the rapid urbanization and industrialization, a growing interest has been devoted in developing cost effective and renewable disposal alternatives. Among them, the manufacture of adsorbents to remove metals from water and wastewater appears to be promising, also considering the high cost of commercial carbons. In this paper copper, zinc and cadmium removal from wastewater using adsorbents produced from pyrolysis of sewage sludge is investigated in comparison with commercial adsorbents. The kinetic of the pyrolytic process was studied, and the adsorbents produced under different pyrolysis conditions were characterized. The adsorption capacity of the pyrolyzed material were estimated in batch tests performed in an activated sludge reactor. Results show that the adsorbent materials obtained by sewage sludge pyrolysis increased organic matter removal in activated sludge systems, and limited the inhibition effects of heavy metals. In addition, a chemical activation of the sludge before the pyrolysis resulted in an increase of the adsorption capacity of the obtained adsorbent.