| Summary: | 碩士 === 國立聯合大學 === 環境與安全衛生工程學系碩士班 === 97 === The widespread production and use of pesticide throughout the agricultural industry has resulted in the pollution problem of surface water and ground water. Basically, conventional treatment processes are not very effective for pesticide wastewater treatment. Hence, intensive research for novel technologies with higher efficiency and less amount of waste generated has been stimulated. In this study, one of advanced oxidation processes (AOPs) - photo-Fenton process with promotion by dye-photosensitization and solar light was used to treat a heterocyclic carbamate pesticide - carbofuran (2,3-dihydro-2,2-dimethylbenzofuran -7-yl methylcarbamate) wastewater. To understand intensively the feasibility of the combination of solar photo-Fenton process and photosensitization for treating carbofuran wastewater, the effect of dosage of H2O2, dosage of Fe3+, initial ratio of [H2O2]0/[Fe3+]0 and [Dye]0/[Fe3+]0, light intensity and wastewater temperature on COD degradation and mineralization efficiency of carbofuran pesticide wastewater were examined.
Results showed that carbofuran molecules could be decomposed to lower molecular weight intermediates by attacking of hydroxyl radicals generated from photo-Fenton process with addition of photosensitizer. Carbofuran was found to be decomposed to carbofuran phenol, 3-oxo carbofuran phenol, 3-hydroxyl carbofuran phenol, NO3-, CH3COOH, and (COOH)2. On the basis of the conditions studied, the optimum dosage for the complete destruction of carbofuran molecular structure was found with a [H2O2]0/[Fe3+]0 ratio of 33 (10/0.3) and a [H2O2]0/[Fe2+]0 ratio of 2 % under 500 W/m2 irradiance after treating 20 min. As a result, the COD degradation efficiency of wastewater could be promoted to 61 %, 64.2 %, and 63.3 % from 37.1 % by an addition of methylene blue (MB), alizarin red S (ARS), and alizarin violet 3B (AV), respectively. Meanwhile, the mineralization efficiency of wastewater could be achieved to 29 %, 57 %, and 53.5 % from 21.0 % through the assistance of adding MB, ARS, and AV, respectively. In addition, it was found that the COD degradation and mineralization efficiency of wastewater could be also promoted by increasing light intensity and water temperature, especially under solar irradiation.
Based on the results obtained in this study, it was believed that a great increase in COD degradation and mineralization efficiency of pesticide wastewater could be achieved by adding photosensitizer - dye with an appropriate ratio into solar photo-Fenton system. Consequently, the photo-Fenton process along with the aid of solar irradiation and a photosensitizer, such as ARS or AV, could be a feasible and potential alternative for the treatment of refractory organic pollutants such as carbofuran pesticide wastewater.
|
|---|
