Fig. 4. Effect of Co sorption under different physicochemical conditions on nickel speciation (mg kg^–1 total solids [TS]) in paper mill (Eerbeek) (A) and distillery (Nedalco) (B) granules. For denomination of sorption conditions, see Fig. 3. I, inoculum. Intact granules: (d) and (e) represented as black bars on the secondary axis for 1 mM Ni addition. From left to right, bars represent the following fractions: exchangeable, carbonates, organic matter + sulfides, and residual.