Phosphorus uptake by cattail plants in a laboratory-scale experiment related to constructed treatment wetlands

This paper describes a laboratory-scale study of phosphorus (P) uptake by broad-leaf cattail plants (Typha latifolia) growing in gravel substrate. The cattails were fed synthetic wastewater at P concentrations representative of primary and secondary municipal sewage effluent. Phosphorus uptake to the upper and lower portions of the cattail plants, adsorption to the gravel substrate, and the pore water concentration were measured over a simulated growing season. The objective was to quantify the mass of phosphorus accumulated in each compartment as the growing season progressed. The experimental results show that the partitioning of P between the upper and lower portions of the plants varied throughout the simulated growing season. At the end of the season uptake by cattails had removed about 40% and 45% of the P mass input under the primary and secondary effluent conditions, respectively. Adsorption of P to the gravel substrate and other fine sediments removed about 43% and 56% of the P mass input under the primary and secondary effluent conditions, respectively. The results provide insight into the potential timing and effectiveness of cattail harvesting for removal of P from constructed treatment wetland systems.