Biological leaching of heavy metals from a contaminated soil by Aspergillus niger.
Bioleaching of heavy metals from a contaminated soil in an industrial area using metabolites, mainly weak organic acids, produced by a fungus Aspergillus niger was investigated. Batch experiments were performed to compare the leaching efficiencies of one-step and two-step processes and to determine the transformation of heavy metal chemical forms during the bioleaching process. After the one or two-step processes, the metal removals were compared using analysis of variance (ANOVA) and least-significance difference (LSD). A. niger exhibits a good potential in generating a variety of organic acids effective for metal solubilisation. Results showed that after the one-step process, maximum removals of 56%, 100%, 30% and 19% were achieved for copper, cadmium, lead and zinc, respectively. After the two-step process, highest removals of 97.5% Cu, 88.2% Cd, 26% Pb, and 14.5% Zn were obtained. Results of sequential extraction showed that organic acids produced by A. niger were effective in removing the exchangeable, carbonate, and Fe/Mn oxide fractions of Cu, Cd, Pb and Zn; and after both processes the metals remaining in the soil were mainly bound in stable fractions. Such a treatment procedure indicated that leaching of heavy metals from contaminated soil using A. niger has the potential for use in remediation of contaminated soils.
Ren
Wan-Xia
WX
Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, PR China. ren_laura@163.com
Li
Pei-Jun
PJ
Geng
Yong
Y
Li
Xiao-Jun
XJ
D001234:Aspergillus niger / Q000737:chemistry*; D001673:Biodegradation, Environmental; D002264:Carboxylic Acids / Q000737:chemistry* / Q000378:metabolism; D019216:Metals, Heavy / Q000302:isolation & purification*; D012989:Soil Pollutants / Q000302:isolation & purification*
D002264:Carboxylic Acids; D019216:Metals, Heavy; D012989:Soil Pollutants