Improvement of Stream Water Quality by a Constructed Wetland in Korea

摘要

The performance of a free water surface flow constructed wetland designed to improve the water quality of a stream from a forested/agricultural watershed was investigated. Typical physico-chemical and water quality parameters were measured during the initial year of its operation between April and December, 2009. Significant reductions were achieved for phosphate, total nitrogen and TKN after passing the sedimentation zone and deep marsh regions. The highest cumulative removal rates were obtained for phosphate (51 ± 22%), ammonium (44 ± 21%) and phosphorus (38 ± 19%). The surrounding temperature affected the stability of the physico-chemical constituents (i.e., pH and DO) only until the shallow marsh region. Reduction of constituents seemed less effective during the cold weather period in the winter and the system was more favorable during moderate temperature (15～25°C) from May to September. While overall mass may not have been removed, levels of pollutants were reduced to appreciable levels. The treated effluent quality was evaluated according to stream surrounding standards which achieved the highest grade level indices for pH, SS, and DO. The monitoring is currently underway to determine the actual treatment performance of the system and to provide guidance in design, operation and maintenance.