Characteristics of contaminant and phosphorus existence types in sediment of a constructed wetland

Abstract

ABSTRACT This research investigated the physical and chemical characteristics of sediment deposited at the bottom soil layer of free water surface flow constructed wetland (CW) treating runoff impacted stream water from an agricultural area which is important when determining the long-term maintenance requirements over the lifetime of the CW. Based on the findings, the influent to the CW still was polluted with high concentration of nutrients with TN and TP exceeding five and two times the water quality standard in rivers and lakes. The accumulation of sediment at the first treatment unit (sedimentation zone) of the CW augmented after the summer season signifying that the dredging of sediment must be conducted after the rainy season or until before the winter season. It was found out that the main phosphorus (P) types existing at the sediment in the CW were residual-P (R-P) and non-apatite-P (NAI-P) constituting to almost 90% of total P. While NAI-P can be released in the natural environment by increasing...