Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/31/2009
Publication Date: 3/10/2010
Citation: Polomski, R., White, S., Bielenberg, D., Bridges, W., Klaine, S., Albano, J.P., Whitwell, T. 2010. Effect of N:P ratio of influent on biomass, nutrient allocation, and recovery of Typha latifolia and Canna 'Bengal Tiger' in a laboratory-scale constructed wetland. Available: http://www.usawaterquality.org/conferences/2010/PDF's/Polomski. Interpretive Summary: Constructed wetlands (CWs) are an effective low-technology approach for treating agricultural, industrial, and municipal wastewater. Recovery of phosphorous by constructed wetland plants may be affected by wastewater nitrogen to phosphorous (N:P) ratios. This study tested this hypothesis by subjecting two wetland plants, canna and cattail to treatment solutions with varying ratios of N and P. We found that as the concentration of N and P applied in treatment solution increased, the concentration of N and P in plant tissue of both canna and cattail, increased. Canna ability to take up P greatly exceeded that of cattail. The results demonstrate that plant selection for a constructed wetland is an important consideration for treatment of P contaminated water.
Technical Abstract: Constructed wetlands (CWs) are an effective low-technology approach for treating agricultural, industrial, and municipal wastewater. Recovery of phosphorous by constructed wetland plants may be affected by wastewater nitrogen to phosphorous (N:P) ratios. Varying N:P ratios were supplied to Canna 'Bengal Tiger' and Typha latifola in a laboratory-scale subsurface flow CW system with a 4-day hydraulic retention time in a climate-controlled greenhouse. Typha latifolia and Canna 'Bengal Tiger' recieved five treatments that comprised the following the following N:P ratios: 6:1, 3:1, 1:1, 1:3, and 1:6. Mean total P concentrations ranged from 6.9 (6:1) to 252.2 milligrams per liter (1:6) P; nitrate-nitrogen (NO3-N) was maintained at a constant mean level of 42.4 milligrams per liter. At 60 days Canna shoot P concentration was 13.9 and 19.8 milligrams per gram in the 1:3 (126 milligrams per liter P) and 1:6 treatments, respectively, which greatly exceeded Typha shoot P concentration of 2.4 and 3.0 milligrams per gram in the 1:3 and 1:6 treatments. Typha and Canna whole plant N:P concentration was lineraly correlated with N:P treatment ratios. For the 1.3 and 1.6 treatments, Canna assimilated 40.7 and 30.6% of supplied P compared to 9.7 and 6.2% for Typha. Although both species exhibited luxury consumption of P, Typha latifolia may have been nitrogen-limited at the 1:1, 1:3, and 1:6 N:P ratios. Differential accumulation of P relative to N suggests that N:P of wastewater and the N:P assimilation ability of plants used in constructed treatment wetlands should be considered when designing treatment wetlands for nutrient attenuation.