In situ bioremediation of soil contaminated with explosives was studied using columns packed with contaminated soil. Several operating strategies were investigated including continuous flooding of the soil column with dilute molasses or succinate solution, and periodic operating cycles consisting of flooding followed by draining and aeration. Two control columns were also used, which were flooded with deionized water All of the soil columns that received molasses solution degraded 2,4,6-trinitrotolunene (TNT) and other explosive contaminants present in the soil. However; the most efficient removal of contaminants in terms of TNT removal rates was achieved by the soil column that was operated periodically with flooding with molasses solution, followed by draining and aeration. The columns that received succinate as co-substrate did nor perform well. In control columns with deionized water; there was no removal of TN?: Results of this study will aid in improving the design and operation of field-scale bioremediation systems. (C) 1997 Elsevier Science Ltd.