| Autor: |
Jéglot, Arnaud1,2 (AUTHOR) arnaud.jeglot@agro.au.dk, Miranda-Velez, Jorge Federico1 (AUTHOR), Plauborg, Finn1,2 (AUTHOR), Elsgaard, Lars1 (AUTHOR) |
| Předmět: |
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| Zdroj: |
Environmental Technology. Dec2023, Vol. 44 Issue 28, p4324-4333. 10p. |
| Abstrakt: |
Denitrifying woodchip bioreactors (WBRs) remove nitrate ( NO 3 − ) from agricultural drainage water at field-scale, but their efficacy at cold temperatures remains uncertain. This study shows how hydraulic residence time (HRT) controls NO 3 − removal and environmental side-effects of WBRs at low water temperature under pilot-scale conditions with controlled operation of nine WBRs (94 dm3). Hydraulic properties were assessed by a bromide tracer test, and NO 3 − removal, emissions of nitrous oxide (N2O) and methane (CH4), and losses of dissolved organic carbon (DOC) were measured at HRTs of 5–30 h. Inlet NO 3 − concentrations were increasingly reduced at higher HRTs. The relationship between HRT and the efficiency (%) of NO 3 − removal was linear ( R a d j 2 = 0.94), while the relationship between HRT and NO 3 − reduction rates (NRR) was logistic ( R a d j 2 = 0.88). Gaseous emissions of N2O were equally low at HRTs of 10–30 h, but higher at 5 h (P < 0.05). Methane fluxes were small, but with consistent emissions at HRTs of 20–30 h and uptake at 5–15 h. HRT had limited effect on effluent DOC concentrations, but strong effect on mass losses that were five-fold higher (320 mg L−1) at the HRT of 5 h than at 30 h. In summary, at cold temperatures HRTs of ≤ 20 h resulted in suboptimal NRR, accelerating DOC losses, and increased risk of N2O losses at least below a threshold HRT of 5–10 h. HRTs of 20–30 h gave maximal NRR, smallest losses of DOC and N2O, but an increased risk of CH4 emissions. [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
| Externí odkaz: |
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