ABSTRACT
Various aromatic compounds, in particular phenols and aromatic amines, are present in wastewaters of numerous industries such as coal conversion, petroleum refining, organic chemicals, and dyes. Most of these compounds are toxic and some have been determined to be human carcinogens; therefore, the removal of such compounds from industrial aqueous effluent is of great practical significance.
An enzymatic method for the removal of phenols from industrial aqueous effluent has been developed in the past several years. In this method, peroxidase enzymes catalyze the oxidation of phenol with hydrogen peroxide, generating phenoxy radicals. These radicals diffuse from the active site of the enzyme into solution and react nonenzymatically to eventually form higher oligomers and polymers which can be removed from wastewater by sedimentation or filtration.
In this study, Arthromyces ramosus peroxidase (ARP) was applied to remove 1.0 mM phenol in synthetic wastewater in a continuous flow system. The system consisted of a mixing tank where hydrogen peroxide was added to the mixture of phenol, enzyme, and polyethylene glycol (PEG) to initiate the reaction. A plug flow reactor where the reaction takes place was followed by a flocculation tank where the alum was added, and finally the polymers formed were settled in a sedimentation tank and removed from the system.
The removal efficiency of the system was dependent on the enzyme dose, molar ratio between hydrogen peroxide and phenol, pH, and PEG concentration. These parameters were optimized first using batch experiments, and then applied to the continuous experiments.
