Experimental Study of Biodegradation of Ethanol and Toluene Vapors

The simultaneous degradation of toluene and ethanol by Pseudomonas GJ 40
and P. GJ31 was conducted by Corseuil et al. (1998) in a continuous-flow bioreactor
that operated as a chemostat (working volume 0.75 L; minimal salts medium pH 7.0;
30 o C; dilution rate 0.1 to 0.5 h -1 ; air flow rate 1.5 L/h). Both Pseudomonas strains were
capable of fast growth on ethanol. A pure culture of Pseudomonas putida F1 (PpF1)
was reported to simultaneously degrade ethanol and toluene with no apparent inhibitory
effect up to 500 g ethanol m -3 (Hunt et al., 1997). The results demonstrated that the
growth of PpF1 on ethanol was faster than other substrates, including toluene.
Microorganisms that grow on toluene have been isolated (Alvarez and Vogel ,
1991; Lodaya et al., 1991; Vipulanandan et al., 2000). The degradation of toluene has
also been investigated using activated sludge (Goldsmith and Balderson, 1988; Alvarez
and Vogel, 1991; Lodaya et al., 1991; Falatko and Novak, 1992; Goudar et al. 1999;
Vipulanandan et al., 2000; Nakao et al., 2000). Vipulanandan et al.(2000) conducted the
biodegradation of liquid toluene in continuously stirred batch reactors using activated
sludge (mixed culture) from a wastewater treatment plant. Toluene concentrations up to
100 g m -3 were degraded with a lag time of 19 days and a total time of 28 days for
complete biodegradation of toluene. They also found that the lag time for toluene
degradation increased with initial toluene concentration.
Vecht et al. (1988) investigated the growth of Pseudomonas putida (ATCC
33015) in batch and continuous cultures on toluene as sole carbon and energy sources.
Toluene vapour was introduced into the culture through the air stream. A mass balance
was performed on the chemostat culture. About 60% of the toluene was recovered in the
outlet air stream. Up to 70% of the toluene which entered into the solution was
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