Author
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Allred, Barry |
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Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/1/2009 Publication Date: 3/17/2010 Citation: Allred, B.J. 2010. Laboratory Batch Test Evaluation of Five Filter Materials for Removal of Nutrients and Pesticides From Drainage Waters. Transactions of the ASABE. 53(1):39-54. Interpretive Summary: Subsurface drainage systems in both large and small scale settings can discharge nutrients and pesticides into local waterways, producing adverse environmental consequences. Filter treatment has potential to remove nutrients and pesticides from drainage waters before these waters are released into local streams and lakes. However, in order to use filter treatment technologies for this purpose, low cost, effective, and efficient filter materials need to be found. Initial laboratory screening of 55 industrial products/byproducts isolated five potential filter materials. These five filter materials are a steam activated carbon, fly ash from a coal-fired power plant, sulfur modified iron, iron sulfide, and a surfactant modified zeolite. This research focused on laboratory batch tests to further document the effectiveness and efficiency of these five filter materials for removal of nutrients (nitrate and phosphate) and a pesticide (atrazine) from water. Effectiveness was tested against moderate, high, and extreme initial concentration levels of nitrate, phosphate, and atrazine in drainage water, while efficiency was evaluated with respect to the exposure time needed to remove nitrate, phosphate, and atrazine. Laboratory results showed that to a greater or lesser extent, all five filter materials removed significant amounts of nitrate, phosphate, and atrazine. Sulfur modified iron proved best for treating nitrate, based on reductions greater than 95% across the range of initial concentration levels and exposure times. Surfactant modified zeolite and the fly ash affected the greatest removal of phosphate, 80% or more in all cases. For atrazine, the most promising results were obtained with the steam activated carbon, and the fly ash, which regardless of initial concentration level and exposure time, removed almost 100% of this particular pesticide. Consequently, there are several filter materials, when used either alone or in combination, that have potential to remove contaminants from drainage water. Technical Abstract: Fertilizer nutrients and pesticides applied on farm fields, especially in the Midwest U.S., are commonly intercepted by buried agricultural drainage pipes and then discharged into local streams and lakes, oftentimes producing adverse environmental impacts on these surface water bodies. Various filter materials have the potential to remove nutrient and pesticide contaminants from agricultural drainage waters before these waters are released off the farm field. Previous batch test screening of 55 industrial products/byproducts found five filter materials exhibiting substantial potential to remove mixed contaminants (nitrate, phosphate, and atrazine) from drainage water. These five materials were a steam activated carbon, sulfur modified iron, iron sulfide, surfactant-modified zeolite, and a high calcium oxide - high carbon fly ash. Additional batch tests were then conducted which focused strictly on evaluating the contaminant removal effectiveness and efficiency of these five materials based on initial nutrient/pesticide aqueous concentration levels and exposure times. Effectiveness was tested against initial contaminant solution concentrations that varied between 10 and 200 mg/L for nitrate-N, 0.1 and 1.0 mg/L for phosphate-P, and 0.1 and 0.5 mg/L for atrazine, while efficiency was evaluated with respect to exposure time by varying test durations from 1 to 24 hours. To a greater or lesser extent, all five filter materials removed significant amounts of nitrate, phosphate, and atrazine. Sulfur modified iron proved best for treating nitrate, based on reductions greater than 95% across the range of initial concentration levels and exposure times. Surfactant modified zeolite and the high calcium oxide - high carbon fly ash affected the greatest removal of phosphate, 80% or more in all cases. For atrazine, the most promising results were obtained with the steam activated carbon, and the high calcium oxide - high carbon fly ash, which regardless of initial concentration level and exposure time, removed almost 100% of this particular pesticide. Consequently, there are several filter materials, when used either alone or in combination, that have potential to remove contaminants from drainage water; however, hydraulic conductivity measurements, laboratory flow cell experiments, field pilot tests, and economic analysis are all needed to determine if any of the five filter materials evaluated in this study have feasibility for widespread agricultural use. |
