We studied the effects of fuel concentration (diesel and gasoline), nitrogen concentration and culture type on the biodegradation of synthetic effluent similar to what was found at inland fuel distribution terminals. An experimental design with two levels and three variables (23) was used. The mixed cultures used in this study were obtained from lake with a history of petroleum contamination and were named culture C, (collected from surface sediment) and C-2 (collected from a depth of approximately 30 cm). Of the parameters studied, the ones that had the greatest influence on the removal of total petroleum hydrocarbons (TPH) were a nitrogen concentration of 550 mg/L and a fuel concentration of 4% (v/v) in the presence of culture C-1. The biodegradability study showed a TPH removal of 90 +/- 2% over a process period of 49 days. Analysis using gas chromatography identified 16 hydrocarbons. The aromatic compounds did not degrade as readily as the other hydrocarbons that were identified. (c) 2006 Elsevier B.V. All rights reserved.