Removal of heavy metals from industrial wastewater by free and immobilized cells of Aspergillus niger

Aspergillus niger, strain B 77, was immobilized by inclusion in two different polymers: polyvinyl – alcohol hydrogel (PVA) and Ca – alginate. The biomass/polymer matrices were formed into equal size unites of the cubes and spheres, and the resulting biomass/polymer matrices were used to remove heavy metals (Cu2+, Mn2+, Zn2+, Ni2+, Fe3+, Pb2+, Cd2+) from wastewater in shake flask experiments. Total biosorption capacities of the biosorbents were in the following order: free cells (33.3 mg/g) < PVA – biomass (39.8 mg/g) < Ca alginate – biomass (44.6 mg/g). The metal removal efficiencies of the beads Ca alginate – biomass were 96.2% for Cd2+; 90.0% for Pb2+; 80.0% for Fe3+; 72. 8% for Cu2+; 55.4% for Zn2+; 54.4% for Ni2+ and 52.3% for Mn2+, while the removal efficiencies of cubes PVA – biomass for the same heavy metals ions were: 95.0%; 88.0%; 80.0%; 67.1%; 58.5%; 48.9% and 44.6%, respectively. The results obtained from these experiments, were compared with those using dispersed biomass as a sorbent. Promising results were obtained in the laboratory, as effective metal removals were observed.