DEGRADATION OF QUINOLINE BY IMMOBILIZED COMAMONAS-ACIDOVORANS IN A 3-PHASE AIRLIFT REACTOR

Quinoline degradation by Comamonas acidovorans was studied in a contin uously operated three-phase airlift reactor. Porous glass beads were a pplied as support matrix for cell immobilization by colonization. Unde r steady-state conditions (S similar to 0), cell attachment was poor a t low dilution rates but improved considerably with increasing dilutio n rate; Conversion of quinoline was investigated below and above the w ashout for suspended culture (D-crit = mu(max) = 0.42 h(-1)). With imm obilized cells the reactor could be operated at D > mu(max), and compl ete conversion of quinoline was achieved as long as the specific quino line feed rate DS-0/X did not exceed the maximum specific degradation rate (r(S,max). The biofilm thickness was about 100 mu m, and its eff iciency was about 54% compared to suspended organisms. If quinoline ov erloads were supplied to the reactor, quinoline, as well as its pathwa y intermediates, appeared in the reactor and conversion was low. Hence , the immobilized microorganisms remained viable and active. They coul d survive quinoline overloads. If the quinoline feed rate was reduced again, complete conversion was reestablished. (C) 1995 John Wiley and Sons, Inc.