EVALUATION OF PULSED FEEDING STRATEGIES FOR THE COMETABOLIC IN SITU BIOREMEDIATION OF MTBE

Pulsed feeding strategies for a primary growth substrate can be used during in situ bioremediation to minimize competitive inhibition during cometabolic biodegradation of MTBE. Four different feeding strategies of isopropanol (IPA) were investigated to stimulate the biodegradation of MTBE by the propane-oxidizing bacterial strain ENV425 (Envirogen, Inc.): (a) continuous, (b) long pulse duration/low frequency, (c) short pulse duration/high frequency, and (d) short pulse duration/low frequency. The experiments were carried out in a series of inoculated aerobic sand columns (50-cm long, 2.5 cm diameter) containing coarse-grain silica sand and supplied continuously with a buffered feed solution (pH 7) containing nutrients, 0.5 mg/L MTBE, and 100 mg/L hydrogen peroxide. Each experimental treatment received an approximately equivalent mass input of IPA over a 6-day period. Continuous and short pulse duration/high frequency feeding strategies led to non-detectable levels of MTBE (