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Three laboratory scale biofilters filled with different packing materials (peat and sieved sugarcane bagasse) and operating with different microbial cultures (allochthonous and autochthonous bacteria) were run and monitored in parallel to assess the emission rate of airborne bacteria in the biofiltration of benzene-contaminated air streams. The effect of the fluid dynamic and loading conditions on the rate of microbial emission in the air environment was investigated by performing continuous experiments at different inlet benzene concentrations and superficial gas velocities. The experiments prove that the concentration of airborne bacteria in the effluent air from lab-scale biofilters is only slightly higher than in the ambient air. The emission rate is not dependent on superficial gas velocity because of low shear stress exerted by the gas flow. On the other hand, the loading conditions have a strong effect on the emission rate, which increases with increasing growth and degradation rate, and different packing media show remarkably different behaviors., ((c) 2005 Wiley Periodicals, Inc.)

We performed a macrokinetic and quantitative microbial investigation of a continuously operating bench-scale biofilter treating styrene-polluted gases. The device was filled with a mixture of peat and glass beads as packing medium and inoculated with the styrene-oxidizing strain, Rhodococcus rhodochrous AL NCIMB 13259. The experimental data of styrene and microbial concentrations, obtained at different biofilter heights, were used to evaluate the pollutant concentration profiles as well as the influence of styrene loading on biomass distribution along the packing medium. Styrene and biomass concentration profiles permitted detection of a linear relationship between the amount of biomass grown in a given section of the biofilter and that of pollutant removed, regardless of the operating conditions tested. Biomass development in the bed appeared to: depend linearly on pollutant concentration at an inlet styrene concentration of <0.10 g m(-3) in the gaseous stream; achieve a maximum value (7. 10(7) colony forming units per gram of packing material) within a wide styrene concentration range (0.10 to 1.0 g m(-3)); and fall sharply beyond this inhibition threshold. The process followed zeroth-order macrokinetics with respect to styrene concentration, which is consistent with zeroth-order microkinetics with either fully active or not fully active biofilm. The maximal volumetric styrene removal rate was found to be 63 g m(packing material) (-3) h(-1) for an influent pollutant concentration of 0.80 g m(-3) and a superficial gas velocity of 245 m h(-1)., (Copyright 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 29-38, 2003.)

The macro-kinetic behavior of phenol removal from a synthetic exhaust gas was investigated theoretically as well as experimentally by means of two identical continuously operating laboratory-scale biological filter bed columns. A mixture of peat and glass beads was used as filter material. After sterilization it was inoculated with a pure strain of Pseudomonas putida, as employed in previous experimental studies. To determine the influence of the superficial gas flow rate on biofilter performance and to evaluate the phenol concentration profiles along the column, two series of continuous tests were carried out varying either the inlet phenol concentration, up to 1650 mg . m(-3), or the superficial gas flow rate, from 30 to 460 m(3) . m(-2) . h(-1). The elimination capacity of the biofilter is proved by a maximum volumetric phenol removal rate of 0.73 kg . m(-3) . h(-1). The experimental results are consistent with a biofilm model incorporating first-order substrate elimination kinetics. The model may be considered a useful tool in scaling-up a biofiltration system. Furthermore, the deodorization capacity of the biofilter was investigated, at inlet phenol concentrations up to 280 mg . m(-3) and superficial gas flow rates ranging from 30 to 92 m(3) . m(-2) . h(-1). The deodorization of the gas was achieved at a maximum inlet phenol concentration of about 255 mg . m(-3), operating at a superficial gas flow rate of 30 m(3) . m(-2) . h(-1). (c) 1996 John Wiley & Sons, Inc.

The purpose of this study is to investigate the feasibility of biologically removing phenol from waste gases by means of a biofilter using a Pseudomonas putida strain. Two series of both batch and continuous tests have been performed in order to ascertain the microbial degradation of phenol. For the preliminary batch tests, carried out in order to test the effective feasibility of the process and to investigate their kinetic behavior, two different microbial cultures belonging to the Pseudomonas genus have been employed, a heterogeneous culture and a pure strain of P. putida. The results of these comparative investigation showed that the pure culture is more efficient than the mixed one, even when the latter has undergone three successive acclimatization tests. The continuous experiments have been conducted during a period of about 1 year in a laboratory-scale column, packed with a mixture of peat and glass beads, and utilizing the pure culture of P. putida as microflora and varying the inlet phenol concentration from 50 up to 2000 mg m(-3). The results obtained show that high degrees of conversion can be obtained (0.93/0.996) operating at a residence time of 54 s., ((c) 1993 John Wiley & Sons, Inc.)

This article aims at deriving kinetic models for the RBS reactor operating with and without cell porous support. Since derivation of the kinetic equations from the Monod model is very complex, an empirical derivation from experimental data of continuous alcohol fermentations is used in this work.