Gas-phase methyl ethyl ketone biodegradation in a tubular biofilm reactor: microbiological and bioreactor aspects

Odor control and air pollution stemming from volatile organic compounds (VOCs) are becoming an increasingly serious problem. Several biological techniques are currently considered as promising solutions in this area, including biofilters, bio-washers and biotrickling filters (Groenestijn and Hesselink, 1993). These three techniques are well known to be specifically adapted for different classes of gaseous pollutants and all have advantages and disadvantages. On the basis of Henry’s dimensionless constant (H, partition between gas and liquid phase in equilibrium), biofiltration is considered to be particularly efficient for poorly soluble gaseous substances (1 < H < 10), biowashing for very soluble substances (H < 0.01) and biotrickling for intermediately soluble (0.01 < H < 1) and acidifying compounds (Diks et al., 1994; Kirchner et al., 1996). On the other hand, biowashers and biotrickling filters are more expensive and more difficult to construct, operate and maintain than biofilters, but require smaller space than the latter (Groenestijn and Hesselink, 1993).