Premium
Electrokinetic movement and biodegradation of 2,4‐dichlorophenoxyacetic acid in silt soil
Author(s) -
Jackman Simon A.,
Maini Giacomo,
Sharman Ajay K.,
Sunderland Garry,
Knowles Christopher J.
Publication year - 2001
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.1093
Subject(s) - electrokinetic phenomena , biodegradation , cathode , anode , chemistry , silt , soil contamination , environmental chemistry , soil science , soil water , environmental science , electrode , geology , paleontology , organic chemistry
The coupling of electrokinetic movement of an organic contaminant, 2,4‐dichlorophenoxyacetic acid (2,4‐D), through soil and its biodegradation in situ has been demonstrated. In a first experiment, the direction and rate of movement of 2,4‐D were determined using homogeneously contaminated soil (864 mg 2,4‐D/kg dry weight soil) compacted into six individual compartments, 6 cm long, 3 cm wide, and 4 cm deep. Each compartment was bordered by a carbon felt anode and a stainless steel cathode. The application of a current density of 3.72 A/m 2 led to migration of 2,4‐D towards the anode at a rate of approximately 4 cm/day. In a second experiment, electrokinetic movement and biodegradation were combined in situ. Sterilized silt soil contaminated with ring‐labeled 14 C‐2,4‐D (811 mg 2,4‐D/kg dry weight soil) was compacted into a single soil compartment, 22 cm long, 7 cm wide, and 4 cm deep, in a 4.5 cm region adjacent to the cathode. The remainder of the compartment was filled with sterilized soil (to a total weight of 1,015 g). Burkholderia spp. RASC c2 (1.88 × 10 11 cells), a tetracycline‐resistant bacterium with chromosomally encoded degradative genes for 2,4‐D, was inoculated into the soil at a position 14–16 cm from the cathode. The reactor was placed within a sealed perspex box, with a constant air flow connected to sodium hydroxide traps. Under an applied current density of 0.89 A/m 2 , the pollutant moved towards the bacteria. As it reached the inoculated region, its concentration decreased in the soil and 14 CO 2 was recovered in the traps. At the end of the experiment, 87.1% of radiolabel had been removed from the soil, 5.8% of which was recovered as 14 CO 2 . A third, control, experiment showed a significant contrast in the absence of an electric current, where a slow rate of diffusion controlled the movement of both 2,4‐D and bacteria in the soil and biodegradation occurred at the interface between the diffusing fronts. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 74: 40–48, 2001.