Reactor development for peroxidase catalyzed polymerization and precipitation of phenols from wastewater

Horseradish peroxidase enzyme catalyzes the oxidation of toxic aromatic compounds, especially phenols and aromatic amines, in the presence of hydrogen peroxide. The reaction products polymerize to form high molecular weight materials which readily precipitate from solution; hence, providing a means for the treatment of wastewaters which contain aromatic compounds. The catalytic lifetime of horseradish peroxidase enzyme can be extended by optimizing treatment conditions such as pH and temperature and by maintaining a low instantaneous enzyme concentration in the reaction mixture. The enzyme catalyzed polymerization process was implemented in a continuous stirred tank reactor (CSTR) configuration because reactant and enzyme concentrations are lowered immediately upon entering the reactor causing a reduction in inactivation of HRP through free radical bonding and compound III formation. Catalytic turnovers achieved in single and multiple CSTRs in series were significantly higher than those observed in batch reactors when sufficient retention time was provided.