THE ROLE OF DISSOLVED ORGANIC MATTER ON PHOSPHOROUS SORPTION ONTO IRON-ENHANCED ACTIVATED ALUMINA MEDIA USING IN-FIELD AND FLOW-THROUGH COLUMN EXPERIMENTS

The Western Lake Erie basin in Ohio has been experiencing harmful algal blooms due to increases in the export of dissolved reactive phosphorous (DRP) from the agricultural land use in the Maumee River watershed. Agricultural best management practices (BMPs) can be useful to mitigate the DRP discharge; nevertheless, DRP is not always fully retained by in-field BMPs. Therefore, researchers have engineered phosphorous removal structures to trap DRP from tiled drainage. These structures can be filled with phosphorous (P) sorption materials such as iron and aluminum oxides and can be placed at the junction of runoff and subsurface drainage (Edge-of-field BMPs). However, dissolved organic matter (DOM) from the agricultural farmland might compete with phosphate ions at the adsorption sites in the filter, reducing its lifetime and efficiency, which has not been taken into considerations while designing phosphorous removal structures to date. Therefore, laboratory flow-through column experiments will be conducted informed by in-field conditions to determine whether DOM is affecting phosphorous sorption onto the iron enhanced activated alumina media. The laboratory experiment will be informed by the collected field data at Oedy farm, Leipsic, Putnam County, Ohio. For the field data, samples from the inlet and outlet solution were collected after the P removal structure installation for two months at 7-day intervals. The pH, electrical conductivity (EC), total organic carbon (TOC), phosphorus, ammonia, and nitrate concentrations were measured for both the influent and effluent solutions. From the field measurements, it has been pointed out that the alumina media is very efficient in removing DRP. Moreover, it was seen in the field measurement that DOM is being sorbed onto the media. This organic matter sorption can potentially decrease the lifetime of the structure. Therefore, our column experiment would be an important tool to better inform the design and construction of P removal structures. This research aims to determine the efficiency of phosphorous removal from agricultural tile drainage using an iron oxide filter by generating P removal curves and determining the role of DOM on phosphorus sorption onto the iron oxide filter. Thus, the research will contribute to understanding the role of DOM on DRP sorption onto the iron oxide filter and thereby suggest potential implications on the filter efficiency.