Application of Supercritical Fluid Extraction(SFE)to Predict Bioremediation Efficacy of Long-Term Composting of PAH-Contaminated Soil

摘要

Supercritical fluid extraction(SFE)with pure carbon dioxide was used to obtain desorption curves of PAHs from four contaminated industrial soils.Total PAH concentrations ranged from 1495 to 2439 mg/kg.The desorption curves were fitted with a simple two-site model to determine the rapidly released fraction(F)representing bioavailability of PAHs.The F data obtained under various SFE pressures were compared with degradation results of a composting method applied on the soils.After composting and consequent long-term maturation,the residual PAH contaminations ranged from 4 to 36% of the original values.A possible explanation of the result variations is the different bioavailability of the pollutants.The best correlations between degradation results and F fraction were obtained applying 50 deg C and 300 bar.The F values gave very good agreement with degradation efficiencies and the total regression coefficients(r~2)ranged from 0.81 to 0.99.The degradation results together with bioavailable fractions appeared to be consistent with organic carbon contents in the soils and with volatile fractions of organics.The results indicate that SFE could be a rapid test to predict bioremediation results of composting of PAH-contaminated soils.