Denitrifying Bioreactors

Page Contents:

Advantages and Disadvantages
Treatment Details
Cost per Pound of Nitrogen Removed

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

BMP	Effluent Nitrogen Concentration (mg/L)	Nitrogen Reduction (%)	Drainage Area (acres)	Annual Nitrogen Removal (lb/yr)
Infiltration Basin	3.0–6.9	30–70	50	140–326

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