Degradation by gamma radiation of fenitrothion present in sewer water

The present study is focused on the use of gamma radiation to reduce organic compounds in wastewater, first on a synthetic aqueous solution of fenitrothion (FNT), which is an organophosphorus pesticide, then on a real sample of wastewater. On the synthetic solution, the study was conducted with a concentration of l50ppm of fenitrothion submitted to gamma rays of 60Co to absorbed doses varying from l5 to 50kGy. The results showed that on the one hand, the pesticide concentration decreased with dose increasing and, on the other hand, irradiation acidifies the pH of solution, which passed from 5.l7 to 3.2l at 50kGy. The High performance liquid chromatography (HPLC) analysis has shown that 90 % of the fenitrothion contained in the solution was degraded at the dose of 50kGy. Some by-products formed during irradiation were identified. The study on sewer water was conducted on real samples collected from a purification plant effluent that receives industrial and domestic sewer water. Samples were irradiated in 2 -l2 kGy dose range. The results showed the decrease of the pH of the effluent sample with the increase of the absorbed dose. The chemical oxygen demand (COD) of irradiated and non-irradiated samples was determined. The results showed that gamma radiation at the dose of l2kGy reduced by 46%the COD of the effluent. The degradation study was followed by HPLC and GC-MS and the results reveal the presence of trace of fenitrothion in the effluent control sample, this trace disappeared in the sample irradiated at 2kGy.