Reduction of tributyltin (TBT) and other organic pollutants of concern in contaminated sediments by means of an electrochemical oxidation

In contaminated sediments butyltin compounds and PAH can be diminished by means of an electrochemical treatment. The butyltin concentrations of the fine fraction (particle size <20 pm) of a mechanical separation unit were reduced from 350 pg/kg to < 10 μg/kg for tetrabutyltin (TeBT), from 2600 μg/kg to <30 μg/kg for tributyltin (TBT), 380 pg/kg to <100 pg/kg for dibutyltin (DBT), and from 570 pg/kg to <100 μg/kg for monobutyltin (MBT), respectively. Furthermore the sum of PAH concentrations for 16 PAH descended approximately 90% during a residence time in the electrolysis cell of 3 h, while in contrast PCB concentrations remained the same before and after the treatment. Apparently, the presence of PCB limited the application of this process, if the initial concentration exceeded guideline values for relocation. Further investigations have to be undertaken to clarify this point. Nevertheless the promising results obtained from a technical treatment unit have led to the construction of a pilot plant, which is installed in Bremen and operating since the beginning of 2002.