ENGINEERING HUMIFICATION PROCESSES TO IMMOBILIZE PHENOLIC CONTAMINANTS IN SOILS

Sorption-desorption behaviors of several phenolic chemicals (phenol, 1-methylphenol, 2,4- dichlorophenol and 1-naphthol) were studied on two sandy loam soils collected from field and forested sites. 14C-labelled chemicals were used to better track the distribution of the contaminant in the soil matrix. The effectiveness of engineered humification processes catalyzed by horseradish peroxidase enzyme was evaluated for various target chemical-soil combinations. Adsorption and desorption behaviors of the target chemicals were studied in single solute conditions and when two solutes were present as a mixture. Addition of the enzyme resulted in dramatic increases in sorption and binding of phenol, methylphenol and dichlorophenol in single and dual solute systems. Desorption was little or negligible for these chemicals and hysteresis was significantly enhanced upon enzyme addition. Increases in Freundlich n and KF values upon enzyme addition were attributed to the production of hydrophobic polymers in the aqueous phase and new “organic matter” on the soil. Naphthol behaved differently from the other chemicals studied and its behavior was not affected by enzyme addition.