No abstract

No abstract

The ability of a Rhodococcus aetherovorans strain, BCP1, to grow on butane and to degrade chloroform in the 0-633 microM range (0-75.5 mg l(-1)) via aerobic cometabolism was investigated by means of resting-cell assays. BCP1 degraded chloroform with a complete mineralization of the organic Cl. The resulting butane and chloroform maximum specific degradation rates were equal to 118 and 22 micromol mg(protein)(-1)day(-1), respectively. Butane inhibition on chloroform degradation was satisfactorily interpreted by means of a model of competitive inhibition, with an inhibition constant equal to 38 % of the estimated butane half-saturation constant, whereas chloroform (at 11 microM) did not inhibit butane utilization. Acetylene (1,720 microM) induced an almost complete inactivation of the degradation of both butane and chloroform, indicating that the studied cometabolic process is mediated by a monooxygenase enzyme. BCP1 proved capable of degrading vinyl chloride and 1,1,2-trichloroethane, but not 1,2-trans-dichloroethylene. BCP1 could grow on the intermediates of the most common butane metabolic pathways and on the aliphatic hydrocarbons from ethane to n-heptane. After growth on n-hexane, it was able to deplete chloroform (13 microM) with a degradation rate higher than that obtained, at the same chloroform concentration, after growth on butane.

No abstract

The gas behavior in gas−liquid reactors stirred with multiple Rushton turbines was studied. Equipment of two scales and several aspect ratios as well as liquids of different characteristics were used. The gas behavior is modeled with the simple axial dispersion model. Its suitability for these systems is evaluated by means of two different experimental techniquesa dynamic one and steady-state one. The model proves good for water, acceptable with coalescence-inhibiting electrolyte solutions, and rather questionable with viscous liquids. Constant tip speed is an appropriate scale-up criterion for the model parameterat least for coalescent systems. A tentative correlation is also proposed to account for the number of turbines. Scrutinity of the experimental results reveals the model drawbacks.