Abstract
Nitrate removal was examined from May to October 2003 of a surface flow treatment wetland cell, which was a part of a treatment wetland system composed of four wetland cells and a distribution pond The system was established on rice paddy near the Kohung Estuarine Lake located in the southern part of the Korean Peninsula. Effluent from a secondary-level night soil treatment plant was funneled into the system. The investigated cell, 87 m in length and 14 m in width, was created in April 2003. An open water was designed at its center, which was equivalent to 10 percent of its total area. Cattails (Typha angustifolia) were transplanted from natural wetlands into the cell and their stems were cut at about 40cm height from their bottom ends. Average $25.0\;m^3/day$ of effluent from the treatment plant was funneled into the cell by gravity flow and average $24.1\;m^3/day$ of its treated effluent was discharged into the Sinyang Stream flowing into the lake. Its water depth was maintained about 0.2 m and its hydraulic detention time averaged 5.2 days. Average height of the cattail stems was 42.5 cm in May 2M3 and 117.7 cm in September 2003. The number of stems averaged $9.5\;stems/m^2$ in May 2003 and $16.4\;stems/m^2$ in September 2003. The growth of cattails was good. Temperature of influent and effluent averaged 25.9 and $26.7^{\circ}C$, respectively. $NO_3$-N loading rate of influent and effluent averaged 176.67 and $88.09\;mg/m^2\;day$, respectively. Removal of rf03-N averaged $89.58\;mg/m^2\;day$ and its removal rate by mass was about 50%. Considering its initial operating stage in which cattail rhizomes and litter layer on the bottom were not Idly established, the $NO_3$-N removal rate of the cell was rather good.