Mechanochemical and biological degradation of PCB in contaminated marine sediments

Large amounts (megatons) of marine sediments, partly contaminated by toxic recalcitrant organics like polychlorobyphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) and as well as by heavy metals and other inorganic pollutants, result from dredging operations at industrial harbors worldwide. In order to avoid the unsustainable burden of sanitary landfilling of this huge amount of special/hazardous waste and to find out technical and cost effective methods for its detoxification and eventual reuse as building material for new marine embankment, an R&D project has been undertaken. The project is based on two complementary advanced technologies: short mechanochemical (MC) pretreatment, wherein chemical reactions are activated at nano-particle level by collisions with milling bodies in special high energy milling devices, followed by biological treatment (B) with purposely isolated aerobic bacteria like Burkholderia xenovorans. The experimental results aimed at determining the kinetics and the overall technical efficiency of the MC+B treatment of artificially contaminated marine sediments from the harbor of Taranto (S. Italy) indicated that, in the best operating conditions, PCB degradation may be achieved in very effective (∼50 %) and fast (<8 d) manner