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Journal of Environmental Quality Abstract - Special Section: Emerging Technologies to Remove Nonpoint P Sources from Surface Water and Groundwater

Using Flue Gas Desulfurization Gypsum to Remove Dissolved Phosphorus from Agricultural Drainage Waters


This article in JEQ

  1. Vol. 41 No. 3, p. 664-671
    unlockOPEN ACCESS
    Received: Aug 15, 2011

    * Corresponding author(s): ray.bryant@ars.usda.gov
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  1. Ray B. Bryant *a,
  2. Anthony R. Budaa,
  3. Peter J.A. Kleinmana,
  4. Clinton D. Churcha,
  5. Louis S. Saporitoa,
  6. Gordon J. Folmara,
  7. Salil Boseb and
  8. Arthur L. Allenc
  1. a USDA–ARS, Bldg. 3702, Curtin Rd., University Park, PA 16802
    b Constellation Power Generation, 1005 Brandon Shores Rd., FSRC, 2nd Floor, Baltimore, MD 21226
    c Univ. of Maryland Eastern Shore, 11868 Academic Oval, 3111 John T. Williams Hall, Princess Anne, MD 21853. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer. Assigned to Associate Editor Gerwin F. Koopmans


High levels of accumulated phosphorus (P) in soils of the Delmarva Peninsula are a major source of dissolved P entering drainage ditches that empty into the Chesapeake Bay. The objective of this study was to design, construct, and monitor a within-ditch filter to remove dissolved P, thereby protecting receiving waters against P losses from upstream areas. In April 2007, 110 Mg of flue gas desulfurization (FGD) gypsum, a low-cost coal combustion product, was used as the reactive ingredient in a ditch filter. The ditch filter was monitored from 2007 to 2010, during which time 29 storm-induced flow events were characterized. For storm-induced flow, the event mean concentration efficiency for total dissolved P (TDP) removal for water passing through the gypsum bed was 73 ± 27% confidence interval (α = 0.05). The removal efficiency for storm-induced flow by the summation of load method was 65 ± 27% confidence interval (α = 0.05). Although chemically effective, the maximum observed hydraulic conductivity of FGD gypsum was 4 L s−1, but it decreased over time to <1 L s−1. When bypass flow and base flow were taken into consideration, the ditch filter removed approximately 22% of the TDP load over the 3.6-yr monitoring period. Due to maintenance and clean-out requirements, we conclude that ditch filtration using FGD gypsum is not practical at a farm scale. However, we propose an alternate design consisting of FGD gypsum-filled trenches parallel to the ditch to intercept and treat groundwater before it enters the ditch.

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