Feasibility of using ornamental plants ( Zantedeschia aethiopica) in subsurface flow treatment wetlands to remove nitrogen, chemical oxygen demand and nonylphenol ethoxylate surfactants—a laboratory-scale study

Abstract

A lab-scale subsurface flow wetland (SSFW) was studied to assess the effectiveness of using calla lily ( Zantedeschia aethiopica) in SSFW to remove nitrate, ammonium, chemical oxygen demand (COD), and nonylphenol ethoxylate (NPEO) surfactants. Reduction of inorganic nitrogen and COD from wastewater is one of the most important objectives in any water treatment process and is usually used to evaluate the performance of the treatment system. NPEO surfactants are of interest because they are contaminants found in sewage effluents at ppm concentrations that have estrogenic potential. It is very important to remove N, COD, and NPEO from wastewater for protection of aquatic life. The removal performances of these compounds in cells planted with calla lily were compared with unplanted cells. Nitrate, ammonium, total Kjeldahl nitrogen (TKN), dissolved oxygen (DO), redox potential (Eh), hydrogen potential (pH), and COD were quantified in the influent and effluent to evaluate the performance of the wetland in the wastewater treatment. In a separate experiment, removal rates of NPEO surfactants were determined. High removal rates of nitrogen, COD and NPEO were observed in the SSFW. Comparisons between the planted and unplanted treatments indicated that Z. aethiopica significantly influenced the removal rate of nitrogen but not the removal rate of COD or NPEO surfactants.