Mestrado em Engenharia Ambiental

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http://repositorio.ufes.br/handle/10/17612

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Navegando Mestrado em Engenharia Ambiental por Assunto "Ácido 2,4-Diclorofenoxiacético"

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    Avaliação da remoção do ácido 2,4-diclorofenoxiacético (2,4-D) pelo sistema convencional de tratamento de água e pelo processo de nanofiltração
    (Universidade Federal do Espírito Santo, 2013-11-28) Souza, Karoline Barros de; Coelho, Edumar Ramos Cabral; Siman, Renato Ribeiro; Mierzwa, José Carlos; Silva Filho, Eloi Alves da
    Pesticides have contributed to increased agricultural productivity. Nevertheless, its use is related to damage to the environment and public health. The conventional drinking water treatment, widely used in Brazil, is ineffective in removing many of these compounds, requiring the use of alternative technologies. The membrane filtration systems, particularly nanofiltration has been shown to be an efficient technology for the removal of pesticides in water treatment. The aim of this study was to evaluate the removal of the pesticide 2,4-D by conventional drinking water treatment in raw water and by nanofiltration in ultrapure water and filtered water from the water treatment plant. Pesticides were detected and quantified using high performance liquid chromatography with a validated methodology. After the construction of coagulation diagrams for raw water collected in Water Treatment Plant Carapina (Serra, ES) from Santa Maria da Vitória river, the efficiency of conventional drinking water treatment for removing of 2,4-D was performed through assay jar test, with the addition of the commercial pesticide in the raw water. The nanofiltration tests were performed with ultrapure water and filtered water fortified with 2,4-D in triplicate. The samples were characterized according to the parameters: temperature, turbidity, conductivity, absorbance at 254 nm, color, alkalinity, TOC and concentration of the pesticide 2,4-D and 2,4,5-T and metabolite 2,4-DCP. The different tests were evaluated in terms of the rejection of these variables. The conventional drinking water treatment was effective in removing turbidity, absorbance at 254 nm and color, though not allowed the removal of 2,4-D. The NF-90 membrane allowed the removal of turbidity, conductivity, color, absorbance at 254 nm and TOC and also showed high removal of the pesticide 2,4-D. The removal of this pesticide is associated with pesticide molecular weight and charge and with membrane charge and molecular weight cut-off not being influenced by the water matrix. The size exclusion and electrostatic repulsion were the main phenomena observed in the removal of this pesticide. The formation of the metabolite 2,4-DCP was observed in the retentate, which may be associated with an increase in temperature. The water permeability and permeate flux was reduced particularly after nanofiltration tests in filtered water, and may be associated with higher levels of conductivity, absorbance at 254 nm and TOC in this matrix. These parameters can cause changes in the NF-90 membrane, reducing its efficiency. Therefore, the nanofiltration was found to be effective in removing the pesticide 2,4-D and other parameters, attending the maximum allowed values established by Ordinance No. 2914/2011 of the Ministry of Health.