PROTOCOL FOR EVALUATING BIOKINETICS AND ATTAINABLE END-POINTS OF POLYCYCLIC AROMATIC-HYDROCARBONS (PAHS) IN SOIL TREATMENT

This paper describes quantitation of biodegradation kinetics in soil s lurry and compacted soil systems using polycyclic aromatic hydrocarbon s (PAHs) as the test contaminants. The experimental protocol, elaborat ed in this paper, results in the measurement of biokinetic parameters which can be used to quantitate both exsitu and in-situ bioremediation rates and assess the attainable end-points. Biodegradation studies we re conducted for naphthalene using soil slurry, soil wafer and soil co lumn reactors. Microcosm reactors were set-up to acclimate soil microb iota, and carbon dioxide evolution was used as a measure of acclimatio n. It was found that reasonable degree of PAH acclimation was achieved after 250 days of microcosm operation. Abiotic adsorption/desorption studies Bowed that equilibrium was achieved in about 20 hours and appr oximately 45% of the initial amount of naphthalene is adsorbed by the time equilibrium is attained. Further, desorption was much slower than adsorption with equilibrium. being attained in 40 hours. Soil slurry studies conducted in the respirometer showed that oxygen uptake occurr ed after an acclimation time of about 42 hours and that the PAHs were completely biodegraded.