Arsenite oxidation by Alcaligenes faecalis strain 01201 in a continuous-flow bioreactor

As(III) oxidation by a pure bacterial culture, Alcaligenes faecalis strain O1201, was evaluated using a continuous stirred tank reactor. The bioreactor system was operated for 204 days under a wide range of influent As(III) concentrations (500-8,000 mg/L) and hydraulic retention times (25.6-90.7 h) with citrate as the sole carbon and energy source at pH 7 and 30°C. Nine steady-state conditions were obtained with As(III) oxidation, efficiency exceeding 95%. The system quickly recovered from an As(III) overloading at 15,000 mg/day/L while it operated at a HRT of 12.8 h. A material balance analysis revealed, that nearly all the As(III) removed, in the continuous stirred tank reactor (CSTR) was oxidized to As(V) and only 3.2% of the As(III) fed to the CSTR was unaccounted for. Biokinetic parameters, k _mc=0.86 mg/mg cell dry weight/h and K _c=70 mg/L, for As(III) oxidation were obtained using the Monod expression and data obtained at steady-state conditions.