Effectiveness of denitrification bioreactors with woodchips, corn stover, and phosphate-sorbing media for simultaneous removal of drainage water N and P in a corn–soybean system

Olawale Oladeji, Guanglong Tian, Richard Cooke, Essam El-Naggar, Albert Cox, Heng Zhang, Edward Podczerwinski

Research output: Contribution to journalArticlepeer-review

Abstract

Millions of acres of farmland in the midwestern United States (US) are artificially drained, and this contributes to the export of nitrogen (N) and phosphorus (P) from agricultural land to surface water. Using a 36-acre tile-drained farm field, effects of P-sorbing media in combination with a denitrifying bioreactor system constructed with woodchips (WC) and corn stover (CS) on reducing nutrient export in drainage water were tested for 3 cropping years (2018–2020). The field was divided into three subfields as replicates. In each subfield, the drainage water was divided and separately channeled into three bioreactors, each of which contains one of the three different substrates: WC, CS, and CS–WC (1:1 v/v mixture of CS and WC), randomly assigned. The outlet of each compartment contained a 2.25 L flow-through chamber filled with activated iron (Fe) filings as P-sorbing material. Both WC and CS bioreactors were effective in removing drainage NO3 with a 77% (WC), 86% (CS), and 89% (CS–WC) reduction in mean NO3–N concentration. For the three cropping years, the WC bioreactor reduced the total drainage inorganic N (NO3–N + NH4+–N) load by 72%, but the CS bioreactor increased the total inorganic N load in the drainage water due to the substantial release of NH4+ with the decomposition of CS. The breakdown of CS also increased drainage P. The NH4+ and P release decreased with the decrease in the proportion of CS; thus, not more than 10% of CS is recommended for blending with WC to enhance the performance of a bioreactor. The P-sorbing Fe filing media reduced the P loads in drainage by an average of 19% during the 2-year study.

Original languageEnglish (US)
Pages (from-to)341-354
Number of pages14
JournalJournal of Environmental Quality
Volume52
Issue number2
DOIs
StatePublished - Mar 1 2023

ASJC Scopus subject areas

  • Water Science and Technology
  • Pollution
  • Waste Management and Disposal
  • Management, Monitoring, Policy and Law
  • Environmental Engineering

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