Engineering a packed bed biofilter for the cometabolic biodegredation of trichloroethylene by the bioluminescent strain Pseudomonas putida TVA8

The aerobic cometabolic biodegradation of trichloroethylene (TCE) in a biofilter was investigated utilizing the bioluminescent strain Pseudomonas putida TVA8. Toluene was used to induce production of the toluene dioxygenase enzyme, which is capable of fortuitously oxidizing TCE. Toluene and TCE were supplied to the biofilter simultaneously at toluene concentrations ranging from 2.0-12.0 mg/L and constant TCE concentration (330 μg/L). The removal efficiency of TCE was < 5 % due to competitive inhibition. Toluene and TCE were then pulsed separately into the biofilter. In the absence of toluene, the TCE degradation rate was maximized and controlled by enzyme deactivation. The natural system half-life of the enzyme in the absence of TCE was ≈ 266 minutes. The presence of TCE caused rapid enzyme deactivation and was a direct function of the TCE loading. Maximum finite removal in the biofilter was determined to be 3.4 μg TCE/mg cell protein per TCE pulse. Data showed that the biofilter was not energy limited for TCE degradation and TCE did not cause cellular toxicity. It was determined that the biofilter could completely recover from the harmful effects of TCE intermediates in 3 hours, while degrading toluene at a maximum rate of 1.0 mg/L-hr-mg protein. The best case design for TCE degradation resulted in 65 % removal of a 600- 800 μg/L stream for 266 min at an average rate of ≈ 8 μg/L^-1 hr^-1 mg protein^-1. Continual operation required alternating between toluene and TCE phases. The steady state bioluminescence in the presence of toluene at 10-16 mg/L was 1.0x10^-7' to 2.0x10^-7 amps. Toluene initiated an instantaneous response in light production. In the absence of toluene, the decay of light was rapid, and limited by formation of a specific aldehyde. Bioluminescence was not impacted by TCE and could not be used as a control variable for TCE degradation in a pulsing operation.