Evaluation of immobilized biomass beads for removing heavy metals from wastewaters

Abstract

Immobilized biomass beads, which consist of dried and ground sphagnum peat moss immobilized in a porous polysulfone matrix, effectively remove heavy metals from wastewaters under appropriate conditions. This paper examines the procedure for forming the beads and their performance in packed columns. The beads are produced by atomizing an organic dispersion into water, creating droplets that become solid through phase inversion. Increasing the relative biomass content gave slightly lower surface areas. Metal ion break through curves were obtained for metal ions from two actual acid mine drainage wastewaters. The selectivity of the beads for various cations was Fe > Al > Pb > Cu > Cd, Zn > Ca > Mn > Mg > Na. Capacity increases with initial pH of the column after regeneration. Bead titration tests indicate that the immobilized biomass beads have heterogeneous ionogenic adsorption sites. Experimental results also indicate that most of the magnesium removed from water by the immobilized biomass beads is adsorbed and exchangeable with potassium. Under the conditions used here, the immobilized biomass beads have a lower capacity than two commercially available ion exchange resins.