Biodegradation of 2,4-Dichlorophenoxyacetic Acid Contaminated Soil in a Roller Slurry Bioreactor

The bioremediation of 2,4-dichlorophenoxyacetic acid (2,4-D) contaminated soil was studied in a roller slurry bioreactor operated under aerobic conditions. The performance of the roller slurry bioreactor was tested for different concentrations of 2,4-D in sandy loam soil (200, 300, and 500 mg/kg soil). Sewage sludge was used as an inexpensive source of microorganisms which is available in large quantities in wastewater treatment plants. The results show that all biodegradation experiments demonstrated a significant decrease in 2,4-D concentrations. Removal efficiencies of 100, 99, and 97% for the initial concentrations of 200, 300, and 500 mg 2,4-D/kg of soil were obtained after ten days, respectively. Abiotic conditions (reactor without microorganisms) were also performed to investigate the desorption efficiency of contaminants from soil to liquid phase. Different amendments as the surfactants sodium dodecyl sulfate, rhamnolipid and glass beads (with 10% load) were used in the roller slurry bioreactor to reduce the incubation time and to enhance the bioremediation efficiency. The results show that there was no reduction in the incubation time and no significant enhancement in the degradation efficiency of 2,4-D in soil for these amendments.