Main content area

Nitrogen accumulation in a constructed wetland for dairy wastewater treatment

Shamir, E., Thompson, T.L., Karpiscak, M.M., Freitas, R.J., Zauderer, J.
Journal of the American Water Resources Association 2001 v.37 no.2 pp. 315-325
wetlands, nitrogen, wastewater, wastewater treatment, Typha domingensis, Phragmites australis, Scirpus validus, aquatic plants, soil depth, constructed wetlands, concentrated animal feeding operations, bioaccumulation, Arizona
A free water surface (FWS) constructed wetland was installed at a dairy in Glendale, Arizona, to study the potential of such a wetland to remove nitrogen (N) from wastewater. The study objectives were: (1) to determine Nremoval from the wastewater, and (2) to evaluate N accumulation in soil and plant tissues. The system consisted of eight cells (70 x 9 x 1.5 m) planted with Typha domingensis, Scirpus validus, and Phragmites australis. The four cells in series were lined with plastic, and the four cells in a parallel series were lined with clay. Cells received approximately 180 m3/d of partially treated dairy effluent. Plant tissues and soil samples were collected above and below ground from 24 locations during one year. Total N removal from wastewater was about 17 percent. Clay-lined cells accumulated more N in the soil and less N in plant biomass compared with plastic lined cells. Plant biomass accounted for approximately 60 percent of total N accumulated in cells with dense plant communities. Ninety percent of accumulated soil N was organic. Total N accumulated in soil reached a maximum (1,100 mg/kg) eight months after the introduction of wastewater.