About Us | Help Videos | Contact Us | Subscriptions



This article in JEQ

    Received: Mar 10, 2014
    Published: July 15, 2014

    * Corresponding author(s): zeaston@vt.edu


Enhanced Nitrate and Phosphate Removal in a Denitrifying Bioreactor with Biochar

  1. Emily Bocka,
  2. Nick Smitha,
  3. Mark Rogersa,
  4. Brady Colemanb,
  5. Mark Reiterc,
  6. Brian Benhama and
  7. Zachary M. Easton *a
  1. a Dep. of Biological Systems Engineering, Virginia Tech, Blacksburg, VA 24061
    b Dep. of Geology, College of William and Mary, Williamsburg, VA 23187
    c Dep. of Crop and Soil Environmental Science, Virginia Ag Experiment Station, Virginia Tech, Painter, VA 23420


Denitrifying bioreactors (DNBRs) are an emerging technology used to remove nitrate-nitrogen (NO3) from enriched waters by supporting denitrifying microorganisms with organic carbon in an anaerobic environment. Field-scale investigations have established successful removal of NO3 from agricultural drainage, but the potential for DNBRs to remediate excess phosphorus (P) exported from agricultural systems has not been addressed. We hypothesized that biochar addition to traditional woodchip DNBRs would enhance NO3 and P removal and reduce nitrous oxide (N2O) emissions based on previous research demonstrating reduced leaching of NO3 and P and lower greenhouse gas production associated with biochar amendment of agricultural soils. Nine laboratory-scale DNBRs, a woodchip control, and eight different woodchip-biochar treatments were used to test the effect of biochar on nutrient removal. The biochar treatments constituted a full factorial design of three factors (biochar source material [feedstock], particle size, and application rate), each with two levels. Statistical analysis by repeated measures ANOVA showed a significant effect of biochar, time, and their interaction on NO3 and dissolved P removal. Average P removal of 65% was observed in the biochar treatments by 18 h, after which the concentrations remained stable, compared with an 8% increase in the control after 72 h. Biochar addition resulted in average NO3 removal of 86% after 18 h and 97% after 72 h, compared with only 13% at 18 h and 75% at 72 h in the control. Biochar addition also resulted in significantly lower N2O production. These results suggest that biochar can reduce the design residence time by enhancing nutrient removal rates.

  Please view the pdf by using the Full Text (PDF) link under 'View' to the left.

Copyright © 2014. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Facebook   Twitter