Evaluating the ability of Rodococcus erythropolis bacterial cells to remove lead from aquatic environments with a comparative approach between biosorption and bioaccumulation

The comparative removal of lead (II) from water environments was investigated using Rhodococcus erythropolis in two modes of biosorption and bioaccumulation. The morphology of the biosorbent and its surface functional groups was investigated by SEM and FT-IR, respectively. Experiments were performed in discontinuous systems as a function of contact time, lead ion concentration, and biomass dose. Bioaccumulation by living bacterial cells and biosorption by inactive and non-living cells, were done. Biosorption was rapid, and equilibrium was reached in 15 min, while equilibrium in bioaccumulation was reached in 60 min. Initial metal concentration and amount of biomass significantly affected biosorption performance and contact time on bioaccumulation. The maximum biosorption efficiency using 0.1 g of inactive biomass after 15 minutes of contact time was 97.55%. Since metal recovery from inactive cell biomass is easier and can be performed with a higher absorption rate with a lower amount of biosorbent, the use of non-living biomass as a biological adsorbent is more efficient and significant.