Simulation of in situ subsurface biodegradation of polychlorophenols in air-lift percolators.

Air-lift percolator experiments simulated in situ subsurface degradation of 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol, in mixtures and individually, by indigenous microorganisms from a chlorophenol-contaminated aquifer. Inoculation with a chlorophenol(CP)-degrading gram-positive isolate from the CP-contaminated groundwater did not significantly increase CP degradation rates. Feed concentrations of up to 55 mg CP l-1 were degraded. Stable CP degradation was maintained for over 6 months. CP degradation rates up to 54.3 mg l-1 day-1 and effluent concentrations below 40 micrograms CP l-1 were achieved. CP were mineralized as shown by CP reduction, dissolved organic carbon removal and release of inorganic chloride.