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ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Publications at this Location » Publication #346869

Research Project: Developing Agricultural Practices to Protect Water Quality and Conserve Water and Soil Resources in the Upper Midwest United States

Location: Soil and Water Management Research

Title: Novel design and field performance of phosphorus-sorbing and denitrifying bioreactors

item RANAIVOSON, ANDRY - University Of Minnesota
item STROCK, JEFFERY - University Of Minnesota
item Feyereisen, Gary
item Spokas, Kurt
item MULLA, DAVID - University Of Minnesota
item ROSER, MARTA - Collaborator

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/22/2017
Publication Date: 10/25/2017
Citation: Ranaivoson, A., Strock, J.S., Feyereisen, G.W., Spokas, K.A., Mulla, D., Roser, M. 2017. Novel design and field performance of phosphorus-sorbing and denitrifying bioreactors. ASA-CSSA-SSSA Annual Meeting Abstracts. October 22-25, 2017, Tampa, Florida.

Interpretive Summary:

Technical Abstract: A novel bioreactor for removing nitrate-nitrogen (NO3-N) and total phosphorus (TP) in subsurface drainage flow was designed and tested. The prototype consisted of a 1000-L reinforced cubic tank filled with layers of woodchips, corn cobs, and P-sorbing materials. Three materials were selected for the P removal media including steel slag, crushed recycled concrete and limestone. The field experiment consisted of three replications of three experimental treatments and a water distribution system which was designed to divert water from a subsurface drain outlet to each of the nine bioreactors. Potassium acetate (CH3CO2K) was used as an external carbon source to enhance denitrification. The experimental period lasted between May and December 2016 at the Southwest Research and Outreach Center near Lamberton, MN Precipitation during this period was 41% greater than normal. The experiment was divided into two phases: no acetate addition (two periods) and plus acetate addition (four periods). The target flow rate of subsurface drainage water delivered to each bioreactor was 4.0 L per minute Mean discharge rate was 3.5, 3.0, and 2.7 m3 d-1 for the crushed concrete, limestone. and steel slag, respectively. The hydraulic residence time ranged between 3.4 and 4.3 hour. Mean NO3-N concentration ranged from 13.1 to 13.8 mg/L at the cube outlets while that of the untreated source water averaged 19.2 mg/L. Nitrate-nitrogen load reduction ranged between 31 and 37%. Mean TP concentration ranged from 79.3 to 113.2 ug/L at the cube outlets while that of the untreated source water averaged 228.5 ug/L. Total phosphorus load reduction ranged between 25 and 41%. This design for bioreactors is meant to be installed directly under a drainage outlet if the ditch geometry allows. Based on the current results, it has the potential to be used as an alternative design to classical denitrifying bioreactor beds for subsurface drainage water treatment.