Leachability and Biodegradation of High Concentrations of Phenol and o-Chlorophenol

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Abstract
The treatability of phenol and o-chlorophenol by solidification/stabilization and phenol by biodegradation was investigated. The effect of two concentrations, 0.1 and 2% of contaminant in cement (equivalent to 2,000 and 40,000 ppm in water), on the setting and solidification process of Type I Portland cement was studied. Leachability of these phenolic compounds from the solidified cement matrix, cured up to 180 days, was evaluated using the U.S. EPA recommended Toxicity Characteristic Leaching Procedure (TCLP) and the American Nuclear Society's ANS 16.1 leaching test. Changes in microstructure of the cement due to the addition of phenol was studied using the X-ray diffraction technique. A power law has been proposed to quantify the phenol leached from the solidified cement matrix during the TCLP test. The phenolic compounds affected the setting time and strength of the solidified cement. Biodegradation of phenol up to 1500 ppm was investigated in batch reactors using an acclimated sludge. The activated sludge, acclimated to phenol at a concentration of 1000 ppm in a three-step process, completely degraded phenol up to 1500 ppm. Both zero and first order degradation of phenol was observed depending on the initial phenol concentration. A new model, more general form of the Haldane model, has been proposed to represent the relationship between specific growth rate and the concentration of the inhibitory substrate phenol. Biokinetic parameters for biodegrading phenol using the acclimated sludge are compared to a few other published data on phenol degradation.