Performance of packed-bed bioreactors for the cometabolic degradation of trichloroethylene by phenol-oxidizing microorganisms

Abstract

Trichloroethylene(TCE), a suspected carcinogen, is highly resistant to biodegradation in conventional biological treatment systems. The feasibility bf cometabolic degradation of TCE by mixed culture obtained from activated sludge plant was investigated in the batch test. Then, three packed-bed reactors filled with GAG, Celite, and Ceramic beads were operated for 285 days in continuous mode. It was observed that the microorganisms utilizing phenol as a carbon and energy source were able to degrade TCE, but phenol degradation was significantly inhibited by increased TCE concentration. Both TCE and phenol were removed most effectively in the GAC packed-bed reactor, degrading over 80% of 9 mg l(-1) TCE. High concentration of phenol inhibited TCE degradation in both the Celite and the Ceramic bead reactors. When influent phenol was reduced to 50 mg l(-1), TCE removal efficiencies increased to about 85% in both reactors