Nitrate Removal and Woodchip Properties across a Paired Denitrifying Bioreactor Treating Centralized Agricultural Ditch Flows

Water

卷:14

Richard A. C. Cooke¹  Mary Foltz²  Ronnie Chacon³  Bryan Maxwell³  Niranga Wickramarathne³  Reid Christianson³  Laura Christianson³ 

[1] Department of Agricultural and Biological Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801-4713, USA;

[2] Department of Civil and Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801-2350, USA;

[3] Department of Crop Sciences, University of Illinois Urbana-Champaign, AW-101 Turner Hall, MC-046, 1102 South Goodwin Avenue, Urbana, IL 61801-4730, USA;

关键词: passive treatment;    denitrification potential;    drainage ditch;    carbon;    water quality;    ecological engineering;   

DOI  :  10.3390/w14010056

来源: DOAJ

【 摘 要 】

Treatment of nitrate loads by denitrifying bioreactors in centralized drainage ditches that receive subsurface tile drainage may offer a more effective alternative to end-of-pipe bioreactors. A paired denitrifying bioreactor design, consisting of an in-ditch bioreactor (18.3 × 2.1 × 0.2 m) treating ditch base flow and a diversion bioreactor (4.6 × 9.1 × 0.9 m) designed to treat high-flow events, was designed and constructed in an agricultural watershed (3.2 km² drainage area) in Illinois, USA. Flow and water chemistry were monitored for three years and the woodchip and bioreactor-associated soil were analyzed for denitrification potential and chemical properties after 25 months. The in-ditch bioreactor did not significantly reduce nitrate concentrations in the ditch, likely due to low hydraulic connectivity with stream water and sedimentation. The diversion bioreactor significantly reduced nitrate concentrations (58% average reduction) but treated only ~2% of annual ditch flow. Denitrification potential was significantly higher in the in-ditch bioreactor woodchips versus the diversion bioreactor after 25 months (2950 ± 580 vs. 620 ± 310 ng N g⁻¹ dry media h⁻¹). The passive flow design was simple to construct and did not restrict flow in the drainage ditch but resulted in low hydraulic exchange, limiting nitrate removal.

【 授权许可】

Unknown