Integrated approach of metal removal and bioprecipitation followed by fungal degradation of organic pollutants from contaminated soils

This study reports the assessment of a novel process combining sequential treatments of a historically contaminated soil from the ACNA site (Cengio, Savona, Italy), a decommissioned industrial area. The soil was leached with 0.5 M citric acid leading to a removal of metals in the following order: Pb (74.2%) > Cu (72.6%) > Zn (40.2%) > Ni (55.7%) > Cd (41.5%) > Cr > (21.7%) Co > (19%) Fe (8.2%) with a concomitant low removal of organic contaminants (12%). The leachate was then incubated with the metal-resistant Klebsiella oxytoca strain BAS-10, capable of using residual citrate to produce an iron gel that co-precipitated metals. Concomitantly, the leached solid waste was bioaugmented with the autochthonous isolate of Allescheriella sp. DABAC 1 leading to a complete degradation of several organic contaminants, including trichlorobenzene, naphtalene, dichloroaniline and pentachloroaniline. The overall removals of organic contaminants by the fungus were 44.3% and 63.8% in non-leached and leached soil.