Bulk electrolysis with coulometry, at +1·85 V vs Ag/AgCl, 3 mol l−1 KCl, in 20 wt % of H2SO4 using a potentiostat . The amount of charge passed for pretreatment was c. 100 C cm−2 of anode geometric area. The pretreated graphite anode was repeatedly soaked in fresh DIW until no change in pH was detected.http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2672.2006.03051.x/full
have a look at the attached publication. It is a straightforward practical guide on how to grow (certain type) of electroactive biofilms from domestic wastewater that are finally enriched on Geobacter sp.
Regards.
P.S. There is even a video describing step by step the procedure to follow.
Article Waste Water Derived Electroactive Microbial Biofilms: Growth...