Application of brewing waste as biosorbent for the removal of metallic ions present in groundwater and surface waters from coal regions

Groundwater and surface water samples were collected and characterized in physicochemical analyzes. It was verified concentrations of Fe and Mn species greater than those permitted by Brazilian legislation, which may be from water contamination by acid mine drainage in the sampling region. The brewing waste was tested as a biosorbent for the removal of iron and manganese from an aqueous solution prepared based on the results obtained from the physical-chemical analyzes carried out on the underground and surface samples. The biosorbent was characterized using different analytical techniques: SEM, EDS, N2-BET and FTIR. The influence of biosorbent concentration on the metallic species removal was evaluated in batch tests, obtaining an optimum concentration of 2.0 g/L with removal percentages of approximately 87% for Fe and 71% for Mn. The biosorption equilibrium was well described by the Langmuir and Freundlich models. The maximum biosorption capacity obtained was of 4 ± 1 mg/g for Fe and 0.96 ± 0.06 mg/g for Mn. The equilibrium is reached with approximately 5 h of contact between the biosorbent and the solution and the sorption occurs rapidly in the initial phase of the experiment. The kinetic data of iron and manganese biosorption were fit well using Lagergren pseudo-second order model, presenting good linear correlation. The intraparticle model showed multi-linearity, indicating that intraparticle diffusion is the limiting step of the biosorption process. The use of the brewery waste proved to be efficient for metallic ions present in aqueous solution and could be an alternative to contaminated water treatments.