Untersuchungen zum Verhalten von insektizidhaltigen Waessern bei Prozessen der chemischen Nassoxidation

Abstract

The aim of the present work was the investigation of the behavior of insecticide-containing water in different wet-oxidation-processes. As model pollutants the insecticides pirimicarb and imidacloprid were selected. Destination of these investigations was the optimization of the process influencing parameters like temperature, pH-value and added concentration of oxidizing agent and/or catalyst. It could be shown, that under laboratory conditions the utilization of the different oxidation processes, the - photolytical oxidation with ultraviolet light and hydrogen peroxide, - photolytical oxidation with ultraviolet light and ozone - photocatalysis with ultraviolet light and titanium oxide, leads to a degradation of both insecticides. The evaluation of the performed toxicity tests shows that in the luminescent bacteria test for both pesticides before and after treatment no inhibition of the light intensity occurred. In the Daphnia tests however it was shown that in the case of pirimicarb the toxicity towards Daphnia mobility decreases during all irradiation experiments. In the case of imidacloprid it was shown that the with hydrogen peroxide photolytically treated samples are all on the same toxic level. In the case of the with ozone photolytically and the photocatalytically treated samples of imidacloprid the toxicity increases in the first phase of treatment. At the end of the experiments the toxicity against Daphnia was reduced below the initial value of toxicity of imidacloprid. The evaluation of the biochemical degradation, expressed by the quotient of the biological- and the chemical oxygen demand, shows, that for both pesticides for all three applications an improvement could be achieved.