Effect of conventional and household water treatment technologies on the removal of pesticide residues in drinking water, Jimma town, Southwestern, Ethiopia

Abstract

Water resources have been contaminated by pesticides due to the different activities of human beings. Different studies documented that advanced water treatment systems can eliminate pesticides while conventional and household treatment technologies are not well studied. The main aim of the present study is to determine the effect of conventional and household water treatment technologies on the removal of pesticide residue in drinking water. Water samples were collected from the Gibe River (intake point), from each treatment process, and from the distribution system. To determine the effect of the household water treatment process (solar disinfection and boiling), pesticides were spiked into distilled water and then passed through solar disinfection (SODIS) and boiling. The extraction of samples was conducted by following a low-density-based dispersive liquid-liquid microextraction procedure. The result of the study revealed that almost all studied pesticides except o´p-DDT were detected in water samples. Most pesticides that were detected in water samples from our study areas exceeded the maximum residue limits (MRLs), except for p,p’-DDE. The percent reduction of pesticide residue after post-chlorination by conventional water treatment ranges from 11.7% (from 70.83 μg/L to 62.54 μg/L) for p´p-DDD to 97.29% (5510.1μg/L to 149.5μg/L) for Dimethachlor, and the percent reduction of pesticide residue by SODIS and boiling ranges from 2.31% (o´p-DDT) to 54.45% (Cypermethrin) and 27.13% (γ-Chlordane) to 38.9% (p´p-DDE) respectively. This indicates that treatment technologies are important for the reduction of pesticides in water. Since studied pesticides are persistent and the resides were exceed MRL (have a health impact), monitoring of pesticides in treatment plant units is necessary and treatment technology improvement is important to allow further removal of pesticides.