Equilibrium, kinetics, and column dynamics of methyl ethyl ketone biodegradation

Abstract

Equilibrium and kinetic studies of methyl ethyl ketone (MEK) adsorption in compost and granular activated carbon (GAC), the reaction rate and selectivity of microorganisms for MEK biodegradation, and the role of the adsorption capacity of the support medium on biofilter dynamics are investigated in this study. Experiments on MEK degradation using biofilters with either Rhodococcus sp. or a mixed culture showed comparable results, indicating no advantage of a pure culture of Rhodococcus sp. The equilibrium isotherm of MEK in compost is linear in the entire range of concentration typically encountered in biofilters, but on GAC the isotherm is nonlinear. Investigation on adsorption kinetics suggests that the mass transfer is macropore-controlled in both compost and GAC. However, in compost the transport appears to be by molecular diffusion, whereas in GAC it is by a combination of molecular, Knudsen, and surface diffusion. Experimental results show that GAC is better than compost in terms of pollutant removal and handling of the fluctuating input load. A linear driving force approximation is used to describe the transport of solute from the gas phase to the support phase. The resulting linear driving force biofiltration model, using independently measured equilibrium and kinetic parameters, appears adequate for describing the experimental results of biofilter dynamics.