研究実績の概要 |
The possibility of heterogeneous iron catalysts as iron source in bio-Fenton process was studied as well as the application of the process to a pilot-scale constructed wetland in Thailand. As a result, heterogeneous iron catalysts were successfully applied to biological Fenton (bio-Fenton) process in laboratory study; however, this process did not work well in a pilot-scale constructed wetland. Further study will be needed to investigate the optimum conditions for actual wastewater treatment. Iron materials such as colloidal ferrihydrite, ferric ion-exchanged zeolite and magnetite particles were used for this study. A fluorescence probe was used to identify the formations and reaction sites of OH radicals in bio-Fenton process. Strong fluorescence was observed in surface parts in roots of plants. Moreover, in the laboratory batch experiments, a trace organic pollutant was quickly removed after addition of solid iron materials. In field experiments, mefenamic acid and N,N’-diethyl-m-toluamide were selected as target compound because they have been detected in relatively high concentrations. Even colloidal ferrihydrite solution was injected into the wetland, the removals could not be achieved. In addition, no clear relation between consumption of hydrogen peoxide in plants and removals of PPCPs was obtained. Batch experiments using actual wastewater were conducted to confirm that the target PPCPs could be treated. Although a significant decrease of the concentration was observed, it is hard to say the process was effective.
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