Experimental Study of Biodegradation of Ethanol and Toluene Vapors

effect on the growth of P. putida. The growth on ethanol followed the Monod equation
with the maximum growth rate of 0.56 h -1 and yield of 0.59. The results from the batch
growth experiments on benzyl alcohol showed that benzyl alcohol inhibits the growth of
P. putida when the initial concentration of benzyl alcohol in the growth media is
increased. The maximum growth rate was 0.42 h -1 in the inhibition model and the yield
value was 0.45.
By operating the bioreactor in continuous mode using a pure strain of P. putida,
it was possible to continuously convert ethanol into biomass without any losses to the
gas phase or accumulation in the bioreactor at inlet ethanol concentrations of 15.9 and
19.5 mg/L. With ethanol as a co-substrate, toluene was efficiently captured in the
bioreactor and readily degraded by the same strain of P. putida. A toluene removal
efficiency of 89% was achieved with an ethanol inlet concentration of 15.9 mg/L and a
toluene inlet concentration of 4.5 mg/L. With the introduction of benzyl alcohol as cosubstrate
at a feed rate of 0.12 g/h, the toluene removal efficiency reached 97% at
toluene inlet concentrations up to 5.7 mg/L. All the experimental results at steady state
were obtained when the bioreactor operated in a continuous mode at a dilution rate of
0.1 h -1 , an air flowrate of 0.4 L/min, an agitation speed of 450 rpm and a reactor
temperature of 25.0 o C. The results of this study indicate that the well-mixed bioreactor
is a suitable technology for the removal of VOCs with both high and low water
solubility from polluted air streams. The results were achieved at higher inlet pollutant
concentrations compared to existing biofilter treatments.
A metabolic model has been developed to simulate the bioremediation of
ethanol, benzyl alcohol and toluene. For continuous steady state operations, ethanol as
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