| Summary: | 碩士 === 國立臺灣海洋大學 === 河海工程學系 === 103 === Simultaneous removal of ammonium (NH4+-N), iron (Fe+2), and manganese (Mn+2) from portable water by biofiltration needs intensive examination due to its complex removal mechanism and its interactions among pollutants. This study used three sand-biofilters, at empty bed contact time of 8 hours, with continuous operation for examining the removal efficiency. Three influents to the biofilters were prepared using effluents from rapid filter in a conventional water purification plant by adding chlorines, resulting in residual chlorines 0, 0.05, and 0.1 mg/L, respectively. In addition, each influent contained NH4+-N 0.5-2.5 mg/L, Fe+2 1-5 mg/L, and Mn+2 0.2 mg/L. Results indicated that removal of ammonium varied significantly, ranging from 37% to 100%. The best ammonium removal occurred at influent ammonium 5 mg/L, Fe+2 2.5-5 mg/L and zero residual chlorine. Removal of Fe+2 reached 94-100 %, almost independent on the concentrations of Mn+2 and residual chlorine. However, high ammonium concentration would slightly reduce the removal of Fe+2. The removal of Mn+2 fluctuated vastly, from 26% to 95%, in which the main removal mechanism was related to biological reaction. High levels of ammonium and residual chlorine would sharply decrease the removal of Mn+2. This study suggested that interactions among ammonium, iron, and manganese occurred in biofilter, and the removal of these pollutants were affected by dissolved oxygen and residual chlorine. It is required to consider the pollutant concentrations, dissolved oxygen, the removal efficiency to achieve, and the residual chlorine in biofilter, during designing efficient biofilter.
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