TOXICITY REDUCTION IN CONTAMINATED SOIL BIOREMEDIATION PROCESSES

Bioremediation processes are used to treat contaminated soil, aquifer material, sludges and residues. The success of such treatment processes lies in: (a) degrading the organic contaminants and (b) reducing both the toxicity and the migration potential of the hazardous constituents. Laboratory studies were conducted using phenolic compounds to characterize overall chemical degradation and toxicity reduction in a contaminated soil, solid phase bioremediation process. The results indicated that: (a) first-order kinetics satisfactorily fit the loss of phenolic compounds and the decrease in toxicity that occurred, (b) contaminant loss in the water soluble fraction (WSF) was faster than loss of the same chemicals in the soil, (c) the toxicity of the WSF decreased as the soil chemical and WSF chemical concentrations decreased and (d) no enhanced mobilization of the applied chemicals resulted as the degradation and detoxification occurred. Results indicated that detoxification as well as chemical loss occur in soil bioremediation processes and suggest that by-products of the degradation and chemical loss mechanisms do not increase the toxicity of the water soluble fraction from such processes.