Protecting & Restoring Long Island's Peconic Bays

Denitrifying Bioreactors

Denitrifying Bioreactors

Page Contents:

Denitrifying bioreactors are an edge-of-field practice that involves the same type of treatment as the described for nitrogen-removing biofilters (NRB) in the Experimental Septic BMP category. For agricultural applications. Denitrifying bioreactors are typically paired with tile drainage systems to treat agricultural drainage.


Advantages and Disadvantages

Advantages:

  • Loss of land for cultivation is significantly less than buffer systems
  • Low energy
  • Low maintenance
  • Low cost

Disadvantages

  • Relatively new technology
  • Nitrogen removal rates can be variable

Treatment Details

The denitrifying bioreactor BMP scenarios considers an agricultural application based on an influent concentration of 9.9 mg/L. The removal efficiency range is from Tyndall and Bowman (2016). The drainage basin size is based on CAST and Tyndall and Bowman (Chesapeake Bay Program 2020; Tyndall and Bowman 2016).

Denitrifying Bioreactor Effluent Concentrations, Nitrogen Reduction, Drainage Area and Annual Removal Rates

BMPEffluent Nitrogen Concentration (mg/L)Nitrogen Reduction (%)Drainage Area (acres)Annual Nitrogen Removal (lb/yr)
Infiltration Basin3.0–6.930–7050140–326

Cost Per Pound Nitrogen Removal

The denitrifying bioreactor BMP capital and O&M costs are from CAST (Chesapeake Bay Program 2020). Capital costs include design and installation, including costs for installation of a tile drainage system, and O&M costs include bioreactor maintenance and replacement of control gates. The annualized total cost includes capital costs annualized over a 20-year lifespan with a 5% discount rate and the annual average O&M costs with a 2% inflation rate.

Denitrifying Bioreactor Capital, O&M, Total Annualized Costs, and Costs per Pound of Nitrogen Removed

BMP TypeCapital CostAverage Annual O&M CostsAnnualized Total CostCost per Pound N Removed
Denitrifying Bioreactor$20,777$57$1,723$9-$21

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