Author(s)

S. Jilani

Abstract

Cypermethrin, a least water soluble pesticide, was selected because such compounds are very difficult to remove from environmental systems by conventional means. In this study, Pseudomonas strain (IES-Ps-1) was used to assess its potential for Cypermethrin degradation. Continuous agitation of a wastewater sample in biosimulator was found to be suitable for growth as well as the metabolism of Cypermethrin by Pseudomonas. At optimum temperature (28- 30ºC) using 8-9 mg/L dissolved oxygen (DO), >85% degradation of Cypermethrin was achieved after 48 hours when the initial added concentration was 80 mg/L. In contrast, at 5-6 mg/L DO, only 38% degradation occurred. When the concentration of DO further increased from 9 to 12mg/l, no pronounced effect on the removal efficiency was observed. Results were confirmed by COD and HPLC analysis. Moreover, during treatment, no significant effect of pH change was observed and the pH remains between 7.3 and 8.8. The findings suggest that IES-Ps-1 strain could effectively be used for the removal of pesticide waste. Keywords: Cypermethrin, Pseudomonas, degradation, agitation, wastewater, biosimulator, dissolved oxygen, pesticide waste. 1 Introduction In Pakistan, insecticides, particularly Cypermethrin, are mainly used for cotton crop protection and for forestry and public health management. The very low water solubility of Cypermethrin and relatively high lipoaffinity indicate a strong bioconcentration potential in aquatic organisms when available as solute [1,2].

Keywords

Cypermethrin, Pseudomonas, degradation, agitation, wastewater, biosimulator, dissolved oxygen, pesticide waste.