Nitrate removal and environmental side-effects controlled by hydraulic residence time in woodchip bioreactors treating cold agricultural drainage water
Denitrifying woodchip bioreactors (WBRs) remove nitrate (NO3-) from agricultural drainage water at field-scale, but their efficacy at cold temperatures remains uncertain. This study shows how hydraulic residence time (HRT) controls NO3- removal and environmental side-effects of WBRs at low water tem...
| Veröffentlicht in: | Environmental technology. - 1993. - 44(2023), 28 vom: 12. Dez., Seite 4324-4333 |
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| Weitere Verfasser: | , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2023
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| Zugriff auf das übergeordnete Werk: | Environmental technology |
| Schlagworte: | Journal Article Bioremediation agricultural drainage water treatment denitrification low-temperature woodchip Nitrates Nitrous Oxide K50XQU1029 Dissolved Organic Matter mehr... |
| Zusammenfassung: | Denitrifying woodchip bioreactors (WBRs) remove nitrate (NO3-) from agricultural drainage water at field-scale, but their efficacy at cold temperatures remains uncertain. This study shows how hydraulic residence time (HRT) controls NO3- 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 NO3- 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 NO3- concentrations were increasingly reduced at higher HRTs. The relationship between HRT and the efficiency (%) of NO3- removal was linear (Radj2 = 0.94), while the relationship between HRT and NO3- reduction rates (NRR) was logistic (Radj2 = 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 |
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| Beschreibung: | Date Completed 06.10.2023 Date Revised 06.10.2023 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1479-487X |
| DOI: | 10.1080/09593330.2022.2091482 |