Experimental Study of Biodegradation of Ethanol and Toluene Vapors

used to degrade ethanol vapours and a maximum elimination capacity of 185 g ethanol
h -1 m -3 of reactor volume was achieved (Shim et al., 1995). Critical ethanol loading,
defined as the maximum loading to achieve greater than 99% elimination at various
residence times have been determined, with typical maximum ethanol loadings of 180
and 109 g ethanol h -1 m -3 of reactor volume at residence times of 12.4 and 1.5 minutes,
respectively.
The performance of a continuously operated biofilter for removal of ethanol
vapour at relatively high inlet concentrations was examined and a maximum elimination
capacity of 195 g m -3 h -1 was achieved (Arulneyam and Swaminathan, 2000).
Concentrations as high as 10 g m -3 could be degraded at a gas velocity of 15 m h -1 ;
however, higher concentrations and higher gas flow rates reduced the removal
efficiency due to mass transfer limitations and short residence times. They also
observed that at all gas flow rates, the elimination capacity increased with increasing
ethanol concentration until a threshold concentration after which it remained constant.
Ethanol vapour was removed using a bioreactor (2.7 m 3 ) packed with a novel microbial
support consisting of a highly porous inorganic matrix coated with a thin layer of
activated carbon (Cioci et al., 1997). The plant was operated continuously for two
months, and the inlet waste air was maintained at a temperature of 20 0 C and a gas flow
rate of 200 m 3 h -1 throughout the experimentation. The ethanol concentration was varied
between 90 and 2200 mg m -3 , and removal efficiencies ranging from 80 to 99.9% were
obtained. An aerobic biodegradation with a concentration of 1 g ethanol m -3 was studied
in an experimental biofilter using wood bark as a packing material (Ramirez-Lopez et
al., 2000). With the addition of nutrient, after 45 days of continuous biofilter operation
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