| The mass transfer of ethanol and toluene from air stream to liquid phase, and bioremediation of contaminated air streams containing either ethanol or toluene have been investigated using a stirred tank bioreactor. This investigation was conducted in six phases: (1) mass transfer experiments involving the transport of toluene and ethanol from contaminated air streams into the liquid phase, (2) study of air stripping effects of ethanol and toluene out of the liquid phase, (3) batch growth experiments to determine growth kinetic models and model parameters, (4) bioremediation of ethanol or toluene as the sole substrate to determine the capacity of Pseudomonas putida (P. putida) (ATCC 23973) growth on these substrates, (5) toluene removal from contaminated air streams using ethanol and benzyl alcohol as co-substrates, and (6) modelling the above studies using metabolic pathways to better understand the bioremediation process.; Preliminary oxygen mass transfer studies showed that the presence of ethanol in the liquid phase enhances the overall oxygen mass transfer coefficients. Increasing the ethanol concentration from 0 to 8 g/L caused the oxygen mass transfer coefficients to increase from 0.015 to 0.049 s-1, and from 0.017 to 0.076 s-1, for impeller speeds of 450 and 600 rpm, respectively. Mass transfer studies using ethanol vapor in the air stream demonstrated complete absorption into the aqueous phase of the bioreactor at all operating conditions investigated (air flowrates up to 2.0 L/min and inlet concentrations up to 95.0 mg/L) and therefore mass transfer coefficients for ethanol absorption could not be determined. On the other hand, toluene mass transfer coefficients could be measured and were found to be 8.3 x 10-4, 8.8 x 10-4 and 1.0 x 10 -3 s-1 at agitation speeds of 300, 450 and 600 rpm, respectively. The ethanol air stripping parameters (beta values) were determined (at initial ethanol liquid concentration of 8.6 g/L) to be 0.002 and 0.007 h-1 for air flow rates of 0.4 L/min (0.3 vvm) and 1.4 L/min (1 vvm), respectively. The toluene air stripping rates, at initial liquid toluene concentration of 440 mg/L, were found to be 1.9, 5.3, 10.4, and 12.6 h-1 for air flow rates of 0.4, 0.9, 1.4, 2.1 L/min, respectively, which is much higher than those of ethanol at the same air flow rates and stirring speed of 450 rpm. It was also observed that benzyl alcohol was not stripped to any detectable level at any of the operating conditions used in this study. (Abstract shortened by UMI.)... |
