IN SITU REMEDIATION OF DDT-CONTAMINATED SOIL USING A TWO-PHASE COSOLVENT FLUSHING-FUNGAL BIOSORPTION PROCESS

摘要

The effectiveness of cosolvent soil flushing and fungal biosorption for the remediation of p, p′-DDT-contaminated soil was evaluated using packed soil columns in order to simulate an in situ soil flushing technique. Greater than 95% of p, p′-DDT (940 mg kg~(-1)) was desorbed from the soil hy flushing with 40 or 80% 1-propanol. Increasing the cosolvent volume fraction increased the rate of p, p′-DDT removal from the soil, however, the extent of p, p′-DDT removal was not enhanced. A further enhancement in the rate of p, p′-DDT removal was achieved by increasing the cosolvent flow rate from 6 ml hr~(-1) to 12 ml hr~(-1) (pore water velocity from 18.9 to 37.8 cm hr~(-1)). The desorbed p, p′-DDT was removed from cosolvent wash solutions by partitioning onto fungal bio-mass. Biosorption of p, p′-DDT resulted in low concentrations of the organochlorine (3.3 μg ml~(-1)) remaining in the cosolvent effluent indicating that the cosolvent could be reused for further p, p′-DDT desorption. Using this technique, between 53 and 95 pore volumes were required to reduce p, p′-DDT concentrations from 990 mg kg~(-1) to below Australian and New Zealand Environmental and Conservation Council (ANZECC) guidelines (50 mg kg~(-1)).