Long‐term performance of co‐metabolic degradation of trichloroethylene in a fluidized bed reactor fed with benzene, toluene and xylene

BACKGROUND: Trichloroethylene (TCE) can be degraded under aerobic condition with toluene and other aromatic compounds. Inhibition by primary substrates and toxicity of TCE oxidation influence TCE degradation. RESULTS: Long‐term co‐metabolic degradation of TCE was evaluated using a laboratory‐scale fluidized bed reactor (12 L) with granular activated carbon (1.57 kg) as media and activated sludge as inoculum. The reactor was fed with TCE and a mixture of benzene, toluene and xylene (BTX) and operated with one‐pass (hydraulic retention time (HRT) of 5–6 min) for 6 months and then with recirculation (HRT of 20–30 min) for 18 months. BTX/TCE‐degrading biofilm was developed within 1 month. TCE was effectively degraded with influent TCE concentrations from 48 to 280 µg L −1 . BTX inhibited TCE degradation. Recirculation (or long HRT) increased TCE removal efficiency from 30% with one‐pass to 90%. BTX/TCE load ratio influenced TCE removal efficiency and TCE/BTX removal ratio. TCE degradation fitted first‐order kinetics. The biomass grown in the reactor also degraded cis ‐1,2‐dichloroethylene (DCE), trans ‐1,2‐DCE and vinyl chloride efficiently except for 1,1‐DCE. CONCLUSION: Co‐metabolic degradation of TCE by BTX‐degrading biomass from activated sludge is sustainable in the long term. BTX/TCE load ratio is a key parameter for TCE removal performance. Copyright © 2008 Society of Chemical Industry