Characteristics of nutrient retention in a stormwater wetland during dry and wet days

摘要

A 0.23-ha pilot wetland was constructed to examine its effectiveness for the control of nonpointnsource pollution (NPS) from a 7.42-ha agricultural watershed in Korea. The wetland wasnoperated during base flow and storm flow conditions and monitored for four years (2006–2009).nThe wetland was operated under high hydraulic loading rates (HLRs, 0.78m/day on average)nduring rainy days. The average influent nitrogen concentration was 9.8mg/L during wet days,nbut around 11.6mg/L during dry days. Due to the short hydraulic retention time (HRT) on wetndays, nitrogen retention at the wetland was poor, only 6.1%; whereas, during dry daysnthe efficiency was higher, around 17.9%. On rainy days, the wetland presented high retentionnfor total phosphorus (TP), with an average efficiency of 68.3%, accompanied with a totalnsuspended solids (TSS) removal of 84.7%. However, on dry days, the wetland showed positivensoluble reactive phosphorus (SRP) retention other than TP. The interior of the wetlandnwas observed to have different nutrients levels. Furthermore, suggestions are addressednin terms of improved design for better performance.