Batch test screening of industrial product/byproduct filter materials for agricultural drainage water treatment

Authors: Allred, Barry

Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2017
Publication Date: 10/14/2017
Publication URL: http://handle.nal.usda.gov/10113/5922760
Citation: Allred, B.J. 2017. Batch test screening of industrial product/byproduct filter materials for agricultural drainage water treatment. Water. 9(10):791. dx.doi.org/10.3390/w9100791.

Interpretive Summary: Discharge of agricultural drainage waters containing nitrate, phosphate, and pesticides can cause adverse environmental impacts on local, regional, and national scales. An in-line filter treatment system located on the main collector pipe near the subsurface drainage system outlet could be a viable means for removing nitrate, phosphate, and pesticides from drainage waters before these waters are released into local streams, rivers, and lakes. Therefore, choosing a suitable filter material for this type of water treatment system will be critical for effective removal of nutrients and pesticides. There are many industrial products/byproducts that could serve as filter materials for drainage water treatment. For this reason, laboratory batch test screening was conducted on 58 industrial product/byproduct filter materials grouped into six categories: (1) high carbon content media, (2) high iron content media, (3) high aluminum content media, (4) surfactant modified clay/zeolite, (5) coal combustion residuals, and (6) spent foundry sands. Results showed that many of the industrial product/byproduct filter materials have capacity to significantly alter water pH, which needs to be taken into account when choosing a filter material, because releasing either extremely low or high pH drainage waters into local waterways could cause ecosystem damage. With regard to nutrient and pesticide treatment, based on a percent contaminant removal criteria of 50 % or greater, 13 industrial products/byproducts met this standard for nitrate, 48 met this standard for phosphate, and 31 met this standard for the organochloride pesticide, atrazine. Based on a more selective percent contaminant removal criteria of 75 % or greater, 7 industrial products/byproducts met this standard for nitrate, 44 met this standard for phosphate, and 25 met this standard for atrazine. Based on an even more stringent percent contaminant removal criteria of 90% or greater, 2 industrial products/byproducts met this standard for nitrate, 37 met this standard for phosphate, and 20 met this standard for atrazine. Using a 50 % or greater contaminant removal criteria, 5 of the industrial product/byproduct filter materials exhibited potential for removing nitrate, phosphate, and atrazine together, 8 showed capability for combined nitrate and phosphate removal, 21 showed capability for combined phosphate and atrazine removal, and 9 showed capability for combined nitrate and atrazine removal. Consequently, there are quite a few possibilities for treating a single drainage water contaminant (e.g. nitrate, phosphate, or atrazine); however, effective treatment of more than one drainage water contaminant simultaneously may require consideration with respect to the mixing of two or more of the industrial product/byproduct filter materials together (assuming chemical compatibility) or installation of a two-stage filter treatment system, with each stage containing a different industrial product/byproduct filter material. Consequently, a number of industrial product/byproduct filter materials were determined to have potential for use in removing nitrate, phosphate, and/or atrazine from drainage waters. For a complete drainage water treatment feasibility evaluation of the most promising of these industrial product/byproduct filter materials, much more extensive research is needed. This additional investigation should include adsorption isotherm and reaction kinetics batch tests, hydraulic conductivity measurements, long duration saturated column experiments, regeneration capacity evaluation, determining the leaching potential for any contaminants originally present with the filter material, pilot scale field demonstrations, and economic analysis.

Technical Abstract: Filter treatment may be a viable means for removing the nitrate, phosphate, and pesticides discharged with agricultural drainage waters that cause adverse environmental impacts within the U.S. on local, regional, and national scales. Laboratory batch test screening for agricultural drainage water treatment potential was conducted on 58 industrial product/byproduct filter materials grouped into six categories: (1) high carbon content media, (2) high iron content media, (3) high aluminum content media, (4) surfactant modified clay/zeolite, (5) coal combustion residuals, and (6) spent foundry sands. Based on a percent contaminant removal criteria of 75 % or greater, 7 industrial products/byproducts were found to meet this standard for nitrate alone, 44 met this standard for phosphate, and 25 met this standard for the organochloride pesticide, atrazine. Using a 50 % or greater contaminant removal criteria, 5 of the industrial product/byproduct filter materials exhibited potential for removing nitrate, phosphate, and atrazine together, 8 showed capability for combined nitrate and phosphate removal, 21 showed capability for combined phosphate and atrazine removal, and 9 showed capability for combined nitrate and atrazine removal. The results of this study delineated some promising industrial product/byproduct filter materials for drainage water treatment; however, a complete feasibility evaluation for drainage water treatment of any of these potential filter materials will require much more extensive testing.