Chemical-physical treatments of marine contaminated sediments - a comparison

Managing of sediments coming from dredging operations in ports, harbor areas and navigation waterways has to deal with huge quantities of highly contaminated material. As a matter of fact, due to routine operations, to the need of deepening fairways and ports and, eventually, to remediation activities, every year more than 200·106 m3 of dredged materials are produced throughout Europe. Chemical-physical treatments are generally used in order to separate a contaminated fraction from a clean one in order to reduce the quantity of sediments to be disposed of. Within this research work, carried out by the Department of Chemical Material Environment Engineering of Sapienza University of Rome and ISPRA (High Institute for Environmental Protection and Research), former ICRAM, sediments coming from a harbor area characterized by metal contamination have been treated adopting three different technologies: sieving, hydro-cycloning and flotation. Results show that sieving, hydro-cycloning and flotation are able to separate products in which metal contaminants generally present lower concentration compared to that of untreated dredged sediments. Nevertheless, in order to further reduce metal content in the cleaned fraction, the examined treatment cannot stand alone as a single step, but a multi steps or a combination of treatments have to be considered.