Enzyme-catalyzed polymerization and precipitation of aromatic compounds from wastewater.

摘要

Horseradish peroxidase (HRP) demonstrates a valuable potential for wastewater treatment by catalyzing the polymerization and precipitation of aromatic compounds from water. It acts on a broad range of compounds including those that are biorefractory or toxic to microbes and retains its catalytic ability over wide ranges of temperature, pH, and contaminant concentration. Removal efficiency is dependent on the nature of the aromatic substrate and the dose of enzyme used. Optimal catalytic lifetime was achieved in the pH range of 7 to 9 for the eight phenolic compounds used in this study. Enzymatic precipitation should be conducted at temperatures below 35$spcirc$C to prevent significant thermal inactivation of peroxidase. The stoichiometry of the reaction between aromatic compound and hydrogen peroxide was unity. Enhanced removal of hard-to-remove compounds was accomplished by co-precipitation with other substrates of HRP. A kinetic model was developed which matches the trends of data collected in a batch reactor under various conditions of enzyme, aromatic substrate and peroxide concentrations. Further development is required to define the mechanisms and kinetics of inactivation to extend application of the model to the design of a full-scale waste treatment system. The catalytic lifetime of the enzyme may be extended 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 free radical inactivation and Compound III formation. Catalytic turnovers achieved in single and multiple CSTRu27s in series were significantly higher than those observed in batch reactors when sufficient retention time was provided.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses u26 Major Papers - Basement, West Bldg. / Call Number: Thesis1991 .N578. Source: Dissertation Abstracts International, Volume: 53-09, Section: B, page: 4923. Supervisors: J. K. Bewtra; K. E. Taylor. Thesis (Ph.D.)--University of Windsor (Canada), 1991.