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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2010.03.019 Byline: Joshua W. Faulkner, Zachary M. Easton, Wei Zhang, Larry D. Geohring, Tammo S. Steenhuis Abstract: Vegetative treatment areas (VTAs) are commonly being used as an alternative method of agricultural process wastewater treatment. However, it is also apparent that to completely prevent discharge of pollutants to the surrounding environment, settling of particulates and bound constituents from overland flow through VTAs is not sufficient. For effective remediation of dissolved agricultural pollutants, VTAs must infiltrate incoming wastewater. A simple water balance model for predicting VTA soil saturation and surface discharge in landscapes characterized by sloping terrain and a shallow restrictive layer is presented and discussed. The model accounts for the cumulative effect of successive rainfall events and wastewater input on soil moisture status and depth to water table. Nash-Sutcliffe efficiencies ranged from 0.65 to 0.81 for modeled and observed water table elevations after calibration of saturated hydraulic conductivity. Precipitation data from relatively low, average, and high annual rainfall years were used with soil, site, and contributing area data from an example VTA for simulations and comparisons. Model sensitivity to VTA width and contributing area (i.e. barnyard, feedlot, silage bunker, etc.) curve number was also investigated. Results of this analysis indicate that VTAs should be located on steeper slopes with deeper, more-permeable soils, which effectively lowers the shallow water table. In sloping landscapes (>2%), this model provides practitioners an easy-to-use VTA design and/or risk assessment tool that is more hydrological process-based than current methods. Author Affiliation: Department of Biological and Environmental Engineering, Cornell University, 62 Riley-Robb Hall, Ithaca, NY 14850, USA Article History: Received 16 September 2009; Revised 16 March 2010; Accepted 27 March 2010

We evaluated the effects of a low-phosphorus compost and vegetation (Panicum virgatum) on the ability of three bioretention cells to remove nutrients and total suspended solids (TSS) from storm runoff originating in a dairy farm production area. The three experimental treatments included a bioretention cell without compost or vegetation (C V), a cell with no compost but vegetation (C-V+), and a cell with vegetation and compost (C + V+); the experimental design allowed for isolation of the variables' (i.e., compost and vegetation) effects on pollutant concentration and mass removal. Influent and effluent were monitored for dissolved and total phosphorus (P) and nitrogen (N), and TSS throughout the first growing season post installation. All bioretention cells significantly reduced pollutant concentrations and loads of TSS, total and dissolved P, and NH 4 + in the effluent, but significantly exported NO x − to the effluent. All cells reduced total N (TN) concentrations, with significant reduction observed only in the C-V+ cell, which was the only treatment that retained TN load. Compost treatment significantly increased P. virgatum biomass, but not survival during the first year. P. virgatum coverage in compost and no-compost treatments were similar the second year. While low-P compost is still preferable to other composts higher in P content, we cannot conclude that any compost is necessary in the soil media for plant establishment. Due to anticipated nutrients inputs in a setting like this dairy operation site, omitting compost and avoiding nutrient leaching while waiting for plants to grow should be considered for better nutrient removal performance, even if plants may take more time to establish. Unlabelled Image • Bioretention cells, whether amended with (a) no compost or vegetation (C V), (b) vegetation with no compost (C-V+), or (c) vegetation and low-P compost (C + V+), reduced concentrations and loads of TSS, dissolved and total P, and NH 4 + in the effluent. • Bioretention cells exported elevated NO 3 − concentrations and loadswith the highest export occurring from the vegetated cell with compost; total N reduction was poorest in the same cell. • Due to anticipated nutrient inputs in a setting like this dairy operation site, omitting compost should be considered for better nutrient removal performance, even if plants may take longer to establish. [ABSTRACT FROM AUTHOR]