255-4 Combining Denitrification and Phosphorus Uptake in Edge-of-Field Bioreactors.
See more from this Division: ASA Section: Environmental QualitySee more from this Session: Managing Denitrification in Agronomic Systems - Innovations and Challenges: I
Tuesday, November 4, 2014: 3:00 PM
Long Beach Convention Center, Room 202B
Nitrogen (N) and phosphorus (P) losses from croplands contribute to impairment of water bodies. This study was conducted to test candidate denitrifying bioreactor media for nitrate-N and dissolved reactive P (DRP) removal from agricultural tile drainage effluent. The nitrate-N and DRP removal performance of candidate media treatments – woodchips (WC), corn cobs (CC), woodchips with biochar (WC+BC), woodchips with continuous sodium acetate injection (WC+A), corn cobs with modified coconut coir (CC+MC), and corn cobs with modified coconut coir and biochar (CC+MC+MBC) – were tested by pumping water with 20 mg/L nitrate and 0.3 mg/L phosphate through PVC columns packed with media. The flow rate was adjusted to match the rise and decay of a typical drainage hydrograph. Effluent was sampled after hydraulic residence times (HRT) of 1.5, 8, 12, and 24 h. Preliminary results show that nitrate-N reduction performance at 15°C during all flow regimes was: WC+A > CC+MC > CC > CC+MC+MBC > WC > WC+BC. Nitrate-N concentration reductions ranged from 99.7 to 54% for 24 h HRT and from 25.4 to 0.4% for 1.5 h HRT. The nitrate-N removal rate for WC+A was 50 g N m-3 d-1 at 1.5 h HRT. Averaged across all HRTs, DRP reduction performance was: CC+MC > CC > CC+MC+MBC > WC+A > WC > WC+BC, ranging from 83 to 12%. In conclusion, denitrification can be coupled with phosphorus uptake in bioreactors. Future work is needed to determine the mechanism of phosphorus uptake.
See more from this Division: ASA Section: Environmental QualitySee more from this Session: Managing Denitrification in Agronomic Systems - Innovations and Challenges: I