DETOXIFICATION OF ORGANOPHOSPHORUS PESTICIDE SOLUTIONS - IMMOBILIZED ENZYME-SYSTEM

Increased regulation of pesticidal chemicals has made the disposal of wastes generated by pesticide users an increasing concern from both an environmental and an economic standpoint. This work utilizes an immobilized enzyme system to degrade pesticides in the organophosphate (OP) class which, while extensively used worldwide on many crops, are often highly toxic to non-target organisms. An enzyme derived from an overproducing strain of Pseudomonas diminuta, called parathion hydrolase (PH), carries out a hydrolysis of the phosphate ester bond in the OP molecule, resulting in an as much as 100-fold reduction in toxicity. Partially purified PH was covalently immobilized upon several rigid supports and retained a large degree of its activity upon immobilization. Three activated controlled pore glasses and a beaded polymer were found to be promising supports for application of the enzyme to the detoxification of contaminated waste waters, offering high mechanical stability and high enzyme capacities. A comparison was made of the four supports on the basis of specificity of binding, amount of protein loading and stability over time. The immobilized enzyme was capable of reducing the concentration of several OP pesticides to sub-ppm levels in both solutions of purified OP's and commercial formulations of commonly used compounds. A field-scale system was designed and its economics were evaluated.