Abstract
PCBs leaked to the environments have been stored in aquatic bottom sediments for a long time. Since PCBs are highly bioaccumulative and disrupt endocrine systems in animals and humans, PCBs-contaminated bottom sediments must be treated for aquatic environment management. Several technologies have been invented for such treatment, whereas these require sediment dredging followed by dehydration of sediments, resulting in the occurrence of wastewater containing PCBs. In the present study, an ozone treatment that requires no dewatering process was tested. KC-300 was used as model PCBs to confirm the feasibility of remediating PCBs-contaminated sediments. 5 g of KC-300 contaminated soil and 95 ml of water were added to the reactor, and then ozone was injected into the bottom for 2 hours. In the control experiment, ozone was substituted by air. The PCBs removal rate by the ozone treatment was determined to be 42 %, while adding 0.5 ml of 30 % hydrogen peroxide as pro-oxidant considerably increased the removal rate of up to 73 %. When the H2O2 reagent was added 4 times, a removal rate of 91 % was attained. Even though the amounts of the contaminated soil treated in this O3/H2O2 system increased four times, removal rates over 90% were achieved by 2 h of ozonation. The degradation of PCBs in the O3/H2O2 treatment obeyed pseudo-second order kinetics. These results confirmed the feasibility of remediating PCBs-contaminated sediments by a O3/H2O2 treatment.
