Improvement of process stability of microbiological quinoline degradation in a three-phase fluidized bed reactor

The biological degradation of quinoline by suspended and immobilized Comamo nas acidovorans was studied under continuous and discontinuous operating co nditions in a three-phase fluidized bed reactor. C acidovorans degrades qui noline into biomass and carbon dioxide. Quinoline and the intermediates of its metabolic pathway are found only by quinoline shockloads. The continuou s degradation of quinoline by suspended biomass was only possible, if the d ilution rate was less than the growth rate (mu (max) = 0.42 h(-1)) and the concentration of a shockload was less than 1 kg/m(3). A concentration great er than 1 kg/m3 led to an irreversible damage of the cells. Hence, two diff erent carrier materials were used for immobilization by attachment, to incr ease the stability of the process. Using immobilization of biomass on carri ers decouples the hydrodynamic retention time and the growth rate of the mi croorganisms. A comparison of the carrier material showed no differences wi th respect of activity and stability of the biofilm. The process stability of a three-phase fluidized bed reactor was increased by immobilized biomass . The degradation of toxic shockloads was only possible with immobilized bi omass. A dynamic model has been developed to describe the concentration pro file of quinoline, 2-hydroxyquinoline as metabolite and the suspended bioma ss. A comparison of the measured and calculated values showed good agreemen t.