Effect of sorption on benzene biodegradation in sandy soil.
The effect of sorption on benzene biodegradation in sandy soil was studied by conducting kinetic microcosm batch tests in soil-free solution and in the presence or absence of bacteria in soil materials with varying degrees of powdered activated carbon (PAC). In the soil-free experiment, benzene was added to a solution inoculated with Pseudomonas aeruginosa bacteria in order to achieve a potential or maximum biodegradation rate. In subsequent experiments, benzene was applied to a solution containing sandy soil and various PAC contents with and without inoculating P. aeruginosa. Benzene concentrations in the soil-free experiments decreased with time with two characteristic rates. A two-stage exponential decay model adequately represented the observed solution concentration pattern with time. Sorption experiments in bacteria-free soil also decreased monotonically, with the extent of sorption increasing as PAC content increased. The sorption data were represented well with a two-stage irreversible sorption model. A third set of experiments in the presence of both soil and bacteria showed more rapid concentration loss from solution than the set of experiments with bacteria-free soil. A model combining sorption and degradation greatly overestimated the loss when the rate coefficient from the bacteria-free experiments was used. Satisfactory agreement between model predictions and observed values was obtained when the degradation rate coefficients were decreased by factors ranging from 3 to 10, depending on the amount of PAC present. Model predictions of the percentage benzene mass remaining in the soil after 25 d of degradation ranged from 72 to 97%, depending on the PAC content, compared to only 2.5% remaining in soil-free solution.
Kim
Song-Bae
SB
Department of Earth and Environmental Sciences, Faculty of Science, Korea University, Anam Dong 5-1, Sungbuk Ku, Seoul 136-701, Republic of Korea.
Hwang
In
I
Kim
Dong-Ju
DJ
Lee
Sangjin
S
Jury
William A
WA
D000327:Adsorption; D001554:Benzene / Q000378:metabolism*; D001673:Biodegradation, Environmental; D005544:Forecasting; D008962:Models, Theoretical; D011550:Pseudomonas aeruginosa / Q000201:enzymology; D012822:Silicon Dioxide; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*
D012989:Soil Pollutants; D012822:Silicon Dioxide; D001554:Benzene