Feasibility Matrix to Identify Locally Sourced Mixed Media to Mitigate Agricultural Pollutants in Land Drainage.

Feasibility matrix to identify locally sourced mixed media to mitigate agricultural pollutants in land drainage Ezzati, G.1*, Healy, M.G.2, Daly, K.3, Christianson, L. 4, Feyereisen, G.5, Thornton, S.6, Fenton, O.7 Teagasc, Environmental Research Centre, Johnstown Castle, Co. Wexford, Ireland *Corresponding author E-mail: Golnaz.Ezzati@teagasc.ie 1* Teagasc, Environmental Research Centre, Johnstown Castle, Co. Wexford, Ireland 2 Civil Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland 3 Teagasc, Environmental Research Centre, Johnstown Castle, Co. Wexford, Ireland 4 Department of Crop Sciences, University of Illinois at Urbana-Champaign, IL, USA 5 USDA-ARS-Soil & Water Mgt. Research Unit, St. Paul MN, USA 6 GPRG, Kroto Research Institute, North Campus, University of Sheffield, UK 7 Teagasc, Environmental Research Centre, Johnstown Castle, Co. Wexford, Ireland The degradation of water quality and ecology as a result of intensification of agricultural activities has affected human health, and aquatic and ecosystem biodiversity. Land drainage systems may create a pathway for loss of nutrients such as phosphorus (P) and nitrogen (N), but also offer an ideal edge-of-field location for bioreactors to intercept and remove or retain such pollutants. Media selection to facilitate attenuation in bioreactors is vital for successful outcomes. Researchers have employed a wide range of novel or traditional media including organic/inorganic, natural and synthetic or waste materials from different sectors to intercept nutrients and remove pollutants in drainage waters at delivery points, but no metric has been used to rank the appropriateness of media selection from environmental, economic and logistical perspectives. This study develops a “feasibility index”, which evaluates and ranks potential media based on a number of factors including N removal rate; P retention; and removal of other contaminants such as pesticides, total suspended solids, dissolved organic carbon, oil, and organic matter; availability and cost (at different scales e.g., local, national and international); permeability, and lifetime. Media can be added to the matrix over time and the media is then ranked with local farm conditions in mind. To date, this feasibility index has been used to evaluate the efficiency and practicality of 61 previously investigated filter media. Results for an Irish dairy farm scenario showed that the majority of the top 20 ranked media include waste materials from agricultural, industrial, construction and demolition industries. Over 90% of the top 10 media could be found locally on Irish dairy farms or in the local vicinity, and were typically low cost. The next step is to test the top 10 materials in controlled batch experiments to compare their treatment capacity with those from the literature and to rank the media accordingly.