Hydrolysis of organophosphate insecticides by an immobilized-enzyme system.

An enzyme preparation that could detoxify parathion and eight other organophosphate pesticides was covalently bound to either porous glass or porous silica beads. This immobilized-enzyme system was examined for its use in detoxification of pesticides in production wastewaters. The kinetics of parathion hydrolysis were examined at flow rates up to 96 liter/hr and at influent substrate concentrations ranging from 10--250 mg/liter. The enzyme reactor was able to hydrolyze 95% or more of the parathion added to industrial wastewaters generated during its production, thus reducing the effluent parathion concentration to below 500 ppb. Laboratory continuous-flow experiments were conducted for 70 days with industrial wastewater and indicated no loss in immobilized-enzyme activity. The influence of pH, temperature, solvents, and detergents on enzyme stability and activity and enzyme reactor kinetics will be discussed.