other questions:

1. What appropriate measurements can I use for NaAsO2 (Volume, concentration and gram) to prepare Fe-As(III) coprecipitates by mixing sodium arsenite (NaAsO2) with 0.1 M iron nitrate (Fe(NO3)3) to obtain 0.01 and 0.05 As/Fe molar ratios?

2. What appropriate microbe (Shewanella oneidensis MR-1) weight is used in a system were heavy metal (As(III)) and mineral (ferrihydrite) are present?