Experiments were carried out in triplicate using sterile Erlenmeyer
flasks with 100ml CDM. The reactionwas initiated by adding
As(III) (NaAsO2) (600 mM), cell cultures (109 CFU ml1) and iron
oxides (1.6 g L1), with a constant ionic strength (0.1 M NaCl). The
initial As concentration was chosen to reach adsorption saturation.
The flasks were shaken at 25 C at 150 rpm for 24 h. During the
experiments, 2 ml samples were removed periodically from the
flasks and passed through a 0.22-mm filter. The concentrations of
total dissolved As were determined using inductively coupled
plasma optical emission spectrometry (ICP-OES, OPTIMA 8300,
U.S.). Then, the amount of adsorbed As was calculated by subtracting
the dissolved As from the total As.