Temporal effects on orhophosphate removal from municipal wastewater in a subsurface-flow constructed wetland

Orthophosphate removal from wastewater in a subsurface-flow constructed wetland (SFCW) was studied during the fall of 1995. The SFCW consisted of a cell with an impervious liner, filled with 1.27 to 3.81 cm river rock and planted with common reeds (Phragmites australis) and soft-stem bulrushes (Scirpus validus). Municipal wastewater was pumped through the wetland and comparisons were made between inlet and outlet orthophosphate concentrations. Comparisons were also made at locations within the cell. A mean orthophosphate reduction of 62% with a range of 91% to 32% was observed for the duration of the study. An ANOVA test showed a significant reduction of orthophosphate in the wetland cell during the study. A regression analysis indicated that inlet wastewater temperatures played a significant role in orthophosphate removal, while outlet wastewater and ambient air temperature were not a significant factor.Keywords: Subsurface-Flow Constructed Wetlands, Orthophosphate, Municipal Wastewater, Water Chemistry, Nutrients.