Core Ideas: Bioreactors can be designed to remove nitrate from drainage ditches. Designing bioreactors for ditch drainage requires site-specific flexibility. All mid-Atlantic ditch bioreactors tested removed nitrate from drainage water. Practical concerns will require adjustments to design and installation. There is strong interest in adapting denitrifying bioreactors to mid-Atlantic drainage systems to help address Chesapeake Bay water quality goals. Three ditch drainage-oriented bioreactors were constructed in 2015 in Maryland to evaluate site-specific design and installation concerns and nitrate (NO3–N) removal. All three bioreactor types removed NO3–N, as measured by load and/or concentration reduction, showing promise for denitrifying bioreactors in the mid-Atlantic's low gradient Coastal Plain landscape. The ditch diversion bioreactor (25% NO3–N load reduction; 0.97 g NO3–N removed m−3 d−1) and the sawdust denitrification wall adjacent to a ditch (>90% NO3–N concentration reduction; 1.9–2.9 g NO3–N removed m−3 d−1) had removal rates within range of the literature. The in-ditch bioreactor averaged 65% NO3–N concentration reduction, but sedimentation is expected to be one of the biggest challenges. A robust water balance is critical for future assessment of bioreactors’ contribution to water quality improvement in low gradient mid-Atlantic landscapes.
ASJC Scopus subject areas
- Agronomy and Crop Science
- Soil Science
- Management, Monitoring, Policy and Law