Processos de oxidação avançada aplicados ao tratamento de águas contaminadas com agrotóxicos

Abstract

In a tropical country like Brazil it is quite difficult to produce food on a comercial scale without effective insect / pest control, especially in so-called 'crops of economic importance' such as soybean, corn, cotton and others, but the growing irresponsible use of agrochemicals can have an impact on the environment, contamination of surface and groundwater is one of these problems, In view of this the need arose to treat this effluent for purposes and reuse. Agrochemicals are widely used in pest control agriculture in Brazil, the insecticide studied in this research is applied in the control of caterpillars and other insects in plantations of cotton, potato, vegetables, corn, soybeans, tomatoes and wheat. This work proposed,the decontamination of synthetically laboratory reproduced effluent contaminated at a concentration of 45 mg/L with an inceticide who haven the active principle METHOMYL by advanced oxidation processes (AOP's): Photo peroxidation (UV + H2O2), Photo-fenton (UV + H2O2+ Fe2+), Fenton (H2O2+ Fe2+) and Peroxidation (H2O2). Contaminated effluent samples were tested under different operating conditions for better degradation performance results. In the treatment by photo-peroxidation processes tests were done at natural pH of the solution and varying the pH of the sample in a range of 4 to 7, the samples were totally decontaminated in a period of 20 to 75 minutes, being observed that the oxidative process with the addition of hydrogen peroxide it works better at more acidic pH. In the tests in which photo-fenton was applied, the proportions of FeSO4 and H2O2 were varied, completely degrading the insecticide between 20 minutes and 110 minutes depending on the proportion applied. The fenton and peroxidation that were done without UV light failed to degrade the contaminant present in the sample. It is concluded that the use of photo-peroxidation and photo-fenton treatments used for insecticide removal is efficient and a great low cost alternative for the reuse of these contaminated waters.