PERFORMANCE OF 3-PHASE FLUIDIZED-BED REACTOR FOR QUINOLINE DEGRADATION ON VARIOUS SUPPORTS AT STEADY-STATE AND DYNAMIC CONDITIONS

Quinoline degradation by Comamonas acidovorans was investigated in a t hree phase fluidized bed reactor at dilution rates below and above the critical value (mu(max) = 0.42 h(-1)). Quinoline was used as the sole source of carbon, nitrogen, and energy. Two attachment carriers, poly urethane foam (Bayvitec(R)) and modified cellulose (Aquacel(R)), and a gel entrapment carrier (polyvinyl alcohol) were studied and compared with regard to their effectiveness to immobilize cells. Attachment and biofilm formation was best at higher dilution rates, regardless of ca rrier type used. Except for the maximum biomass concentration on the c arrier, Y-V (biomass per volume of solid particles), there was no sign ificant difference in reactor performance between the investigated car riers under stationary conditions. The highest value for Y-V was found for the gel entrapment carrier (Y-V = 35 g L-1). In a long-term run ( 66 days), the gel entrapment carrier established a permanent biofilm o n the surface of the gel beads after 900 h of cultivation time. Comple te quinoline mineralization was achieved at a dilution rate of 2.0 h(- 1), which is 4.7 times higher than the critical dilution rate. Identic al substrate overloads were applied to the gel entrapment and the cell ulose carrier by a step increase of the quinoline feed concentration a t a dilution rate of 0.8 h(-1) (D similar to 2 mu(max)). The cells sur vived the overload, but the accumulation of quinoline and quinoline de gradation products and the degradation efficiency were different for t he two systems during the overload, showing the influence of the carri er type on the dynamic performance and stability of the process. (C) 1 997 John Wiley & Sons, Inc.