Heavy metal biosorption by Rhizopus sp. biomass immobilized on textiles

Abstract

Pollution by heavy metals is at present one of the major environmental concerns. In the present study, the potential of the filamentous zygomycete fungus Rhizopus sp. to absorb/adsorb metal ions from solution was investigated. With the aim to develop a feasible process, the fungus was immobilized on 10 different textile materials during the cultivation. All immobilized biosorbents reduced the Cu2+ concentrations initially from 20 to 3.1–5.6 mg/l within 150 min, with the exception of the biomass immobilized on wool, which reduced the Cu2+ level to 10.2 mg/l. The immobilized biomass (with the exception of wool) fitted well into a pseudo-second-order model. The uptake of copper showed a slight dependence on initial metal concentration. By reapplying immobilized Rhizopus sp. to a solution containing a low concentration of Cu2+ after going through a first step of biosorption, a decrease of the concentration to below 2 mg/l was accomplished, meeting the stipulated level for Cu2+ in human drinking water. Immobilization of fungal biomass in a cushion was also successfully applied in the biosorption process. The positive results obtained in a two-step biosorption indicate that a sequential arrangement could be the foundation for a commercial product.Fredrik Wennersten is acknowledged for his expertise regarding weaving and the Swedish Energy Agency for provided financial support