Researches about NPS(Non-point Pollution Source) reduction have been widely carried out in recent years. A pilot
channel-type constructed wetland (wet swale) was constructed in Rongyin area to treat stormwater generated from a
green house agro-land of 22.7 ha. From 2006 to 2008, monitoring was conducted to evaluate its performance on the
removal effect for organic pollutants as well as nutrients. Totally, sampling trips of 17 rainfall events were made and
they covered most types of storm events in Korea. The channel-type constructed wetland have average removal
efficiencies of 78.3~92.0%, 56.4~66.1%, 28.2~45.5% and 50.6~66.4% for SS, COD, TN and TP, respectively.
According to four methods for estimating the removal efficiency, the average efficiencies of TSS, COD, TN and TP are
86.0%, 60.1%, 30.1% and 53.5%, respectively. From 2006 to 2008, annual efficiency improved due to infiltration
potential increase. It was found that most of the pollutants removed in this channel type of wetland was particulate
solids bound pollutants, which is assumed fact that it lacks of physico-chemical treatment conditions which are
commonly observed in the retention type of constructed wetlands.