Performance of long-term, field-scale bioremediation process

The behavior of chemicals over long periods of time must be investigated to assess the effectiveness of bioremediation. Three long-term, field-scale studies are presented and demonstrate the effectiveness of bioremediation at reducing chemical concentrations, mobility, and toxicity in soils and sludges over long time-periods. Two case studies described the land-treatment of wood-treatment site soils and sludges while the third case study described the land-treatment of oily wastes from petroleum industry operations. These long-term studies confirmed that chemicals in bioremediation residues are contained in treated soils, that chemical concentrations continue to decline after active remediation stops, and that toxicity is reduced. Even though significant concentrations of chemicals were present in the residuals, the toxicity and mobility of the residual chemicals and, therefore, the risk associated with them, had been substantially reduced,