摘要
Filamentous fungi were used to leach heavy metals from dredged sediments in semi-pilot scale air-lift bioreactors. Prior to the bioleaching experiments, a physico-chemical characterization of the sediments comprising a sequential extraction study was conducted. The sediments turned out to highly contaminated with heavy metals. Most of the studied metals were found to be strongly linked to the matrix because of their association with the sulphides and with the organic matter. The conditions that favored the solubilization of heavy metals by the filamentous fungi turned out to be favorable for the activity of the sediments organotrophic bacterial microflora as well. The latter played a key role in the biosolubilization process by producing organic acids under temporary anoxic conditions. Better solubilization results (Mn: 77%, Zn: 44%, Cu: 12%, Cd and Pb: <2%) were thus obtained in the uninoculated sugar treatment in comparison to the fungal treatment. In general, organotrophic leaching was found to be limited by the poor nature of the organic acids and by their microbial consumption under sugar limited conditions. It was therefore restrained to the relatively mobile metals, namely those linked to the acid-soluble and reducible fractions of the sediments.
Filamentous fungi were used to leach heavy metals from dredged sediments in semi-pilot scale air-lift bioreactors. Prior to the bioleaching experiments, a physico-chemical characterization of the sediments comprising a sequential extraction study was conducted. The sediments turned out to highly contaminated with heavy metals. Most of the studied metals were found to be strongly linked to the matrix because of their association with the sulphides and with the organic matter. The conditions that favored the solubilization of heavy metals by the filamentous fungi turned out to be favorable for the activity of the sediments organotrophic bacterial microflora as well. The latter played a key role in the biosolubilization process by producing organic acids under temporary anoxic conditions. Better solubilization results (Mn: 77%, Zn: 44%, Cu: 12%, Cd and Pb: <2%) were thus obtained in the uninoculated sugar treatment in comparison to the fungal treatment. In general, organotrophic leaching was found to be limited by the poor nature of the organic acids and by their microbial consumption under sugar limited conditions. It was therefore restrained to the relatively mobile metals, namely those linked to the acid-soluble and reducible fractions of the sediments.
