Environmental applications of enzymes

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Significant quantities of common drugs are produced each year, many of which have been detected in surface waters across Canada. These and other pharmaceutically active compounds (PACs) end up in the environment through untreated and treated effluents. While their concentrations are extremely low, evidence is growing about the adverse effects of exposing aquatic organisms to PACs that exert toxic, estrogenic or other physiological effects. Unfortunately, while municipalities are relying on wastewater treatment plants to remove these compounds from effluents before they are disposed into surface water bodies, such treatment systems have been shown to be quite ineffective. In anticipation of the future implementation of strict guidelines governing the release of PACs, it is necessary to identify and prioritize compounds that are likely to be of greatest concern and to develop treatment approaches to accomplish their removal from waste streams. Therefore, the following objectives are proposed: (1) methods will be developed to predict mass emission rates of PACs from communities, to estimate their concentrations at various stages along the waste train (i.e., from source to influent to effluent), and to explore locations along the waste train where treatment technologies should be implemented; (2) emission rate estimates will be coupled with watershed models to predict concentrations of PACs in surface waters in order to form a basis for the evaluation of risks and the prioritization of efforts for regulating the release of PACs; and (3) enzyme catalysis will be investigated as a method for targeting the treatment of problematic PACs to prevent their uncontrolled release into surface waters. The latter work builds on the extensive research conducted in our laboratory to explore environmental applications of enzymes. The research will involve studies of the ability of oxidoreductases to oxidize PACs in real wastes, evaluation of the feasibility of treating PACs at locations ranging from source to polished effluent, and development of approaches to enhance reaction rates and minimize enzyme costs.