Abstrait

Detoxification of pesticides aqueous solution using horseradish peroxidase

Saad Mohamed El-Said

There are pesticide residues in agriculture wastewaters and that compounds must be removed before discharge of wastewaters in native waters. Thus the aim of this study was to remove toxic pesticide in waste water by the addition of horseradish peroxidase enzyme. The process of pesticide (methyl-parathion (O,O-Diethyl-O-4-nitro-phenylthiophosphate), atrazine (1-chloro-3-ethylamino-5-isopropylamino-2,4,6-triazine) and triazophos (O,O-diethyl O-1-phenyl-lH-1,2,4- triazol-3-yl phosphorothioate) removal from synthetic wastewater using horseradish peroxidase and hydrogen peroxide has been analyzed. The technical feasibility of the process was studied using 0.001 to 3.0 mMsynthetic pesticides solutions. Experiments were carried out at different time, HRP and H2O2 dose and pH to determine the optimum removing conditions. The removal of the three pesticides increases with an increase in HRP and hydrogen peroxide dose. The optimum HRP dose is 2.0 U/l and 10 mMfor H2O2. The contact needed to reach equilibriumwas found to be 360min.Maximumremovalwas achieved up to 74% at pH 8. Also, chemical oxygen demand (COD) of the effluent reduced at the end of 6 h from 2111 to 221 mg L-1 (at pH 8). Tests based upon horseradish peroxidase, at optimized parameters, show the reduction of toxicity to non-toxic levels.