Utilization of biomass residues for the remediation of metal-polluted soils

The utilization of biomass residues as sources for natural chelates is a new approach to improve the ecological and economical balance of leaching techniques for the remediation of metal-polluted soils. Residues, such as molasses, blood meal, and silage effluents, containing various aliphatic carboxylic acids, sugar acids, and amino acids or their precursor compounds were selected, hydrolyzed and oxidized, if required, and analyzed for their organic constituents. Soils that were contaminated with metals via sewage sludge amendment were extracted in batch and column experiments at various pH values. Grass silage effluent removed similar to 75% of Cd and > 50% of Cu and Zn at pH 4.4. The neutralized effluent was less effective except for Cu (69% leached). The neutral blood meal hydrolysate extracted primarily Cu (55-66%) and Ni(38-67%). Metal bonds attacked by this extractant were identified using a sequential leaching procedure. Hydrolysates containing sugar acids mobilized Cu and Pb under alkaline conditions. The actual results support the conclusion that biomass residues have a potential to serve as extractants in remediation techniques.