Micodegradação de metil paration e atrazina em matriz aquosa sintética ultilizando Aspergillus Niger AN 400

Abstract

The present work had as objective to evaluate the capacity of the fungal species Aspergillus Niger AN 400 to degrade the pesticides atrazine (herbicide) and methyl parathion (insecticide) Synthetic aqueous matrix. The research focused on the recalcitrance of pesticides and the Micorremediation of these compounds. The work was divided into 10 steps: Production of spores by the fungal species; Tolerance test of Aspergillus niger AN 400 To the compounds, in petri dishes, with concentrations of 5 to 50 mg L-1 being tested; Reactors In batch with biomass dispersed in agitating table with different rotations, 150 and 80 Rpm, with reaction time of 9 days; Batch aerated by minicompressors, with biomass Dispersed with reaction time of 9 days; Reactor in sequential batches with biomass Immobilized and with a reaction time of 7 days; Experimental planning of the step with Immobilized biomass; Biological test; Toxicity testing of pesticides and pesticides Biodegradation, onions; Pesticide saturation test in biomass and in the environment Support and molecular identification of Aspergillus niger present in biomass reactors Immobilized. In stages III to VI the following parameters were analyzed: demand Biochemistry of oxygen (COD) and pH. The degradation of pesticides was monitored by High performance liquid chromatography (HPLC). In stage II, referring to the test of tolerance Aspergillus niger radial growth was observed in all Petri, both in the presence of atrazine and methyl parathion. On the basis of these results, The concentration of 30 mg L-1 of pesticide was chosen for the following steps. In stage III, the Rotation ratio of 150 rpm gave the highest percentages of removal of both atrazine Of methyl parathion, with 20% removals for atrazine and 45% for methyl Reactors in which methanol was not present. For this phase, COD, in reactors with Atrazine, achieved 99% removal at 150 rpm and 85% at 80 rpm. In reactors with Methyl parathion, the COD removed was 95%, after 4 days of operation at 150 rpm, and 53% After 9 days at 80 rpm. The pH, for the two types of reactors, remained in the acidic range. At Step IV, the best pesticide degradation condition was in the absence of methanol, Atrazine removals of 71, 79, 64, 52, 43, 77 and 64% respectively were obtained for Reactors without glucose and 0.5, 1, 2, 3, 4 and 5 g L-1 of glucose in the medium. The COD in the reactors Without methanol was below the limit allowed by SEMACE, in decree 154/2002, referring to Treated effluent. The pH of the reactors with glucose tended to acidity, While in those where there was only the presence of pesticides increased slightly. At In step V, the removal of atrazine was lower than in the step with dispersed biomass, at The methyl-parathion reactor, for which the mean removals were Higher than those found in the step with dispersed biomass, the best condition being that In which there was addition of 1 g L-1 of glucose (95 ± 2)%. In experimental planning Concentration of pesticides and glucose has had a the treatment. The biological test showed a predominance of fungi to the detriment of bacteria. With respect to the toxicity test with onions, the toxicity of the solutions Containing pesticides decreases after treatment with Aspergillus niger. From biology Aspergillus niger AN 400 was present in the reactors. In short, This study indicates the possibility of using Aspergillus niger AN 400 in the remediation Of pesticides.