Smart operation of nitritation/denitritation virtually abolishes nitrous oxide emission during treatment of co-digested pig slurry centrate

WATER RESEARCH

卷:127

Article

Peng, Lai^1,2  Carvajal-Arroyo, Jose M.¹  Seuntjens, Dries¹  Prat, Delphine¹  Colica, Giovanni¹  Pintucci, Cristina¹  Vlaeminck, Siegfried E.^1,2 

[1] Univ Ghent, Fac Biosci Engn, Ctr Microbial Ecol & Technol, Coupure Links 653, B-9000 Ghent, Belgium

[2] Univ Antwerp, Res Grp Sustainable Energy Air & Water Technol, Dept Biosci Engn, Groenenborgerlaan 171, B-2020 Antwerp, Belgium

关键词: Nitritation/denitritation;    Nitrous oxide;    Pig slurry;    Mitigation strategy;    Carbon footprint;   

DOI  :  10.1016/j.watres.2017.09.049

来源: Elsevier

【 摘 要 】

The implementation of nitritation/denitritation (Nit/DNit) as alternative to nitrification/denitrification (N/DN) is driven by operational cost savings, e.g. 1.0-1.8 EUR/ton slurry treated. However, as for any biological nitrogen removal process, Nit/DNit can emit the potent greenhouse gas nitrous oxide (N2O). Challenges remain in understanding formation mechanisms and in mitigating the emissions, particularly at a low ratio of organic carbon consumption to nitrogen removal (CODrem/N-rem). In this study, the centrate (centrifuge supernatant) from anaerobic co-digestion of pig slurry was treated in a sequencing batch reactor. The process removed approximately 100% of ammonium a satisfactory nitrogen loading rate (0.4 g N/L/d), with minimum nitrite and nitrate in the effluent. Substantial N2O emission (around 17% of the ammonium nitrogen loading) was observed at the baseline operational condition (dissolved oxygen, DO, levels averaged at 0.85 mg O-2/L; CODrem/N-rem of 2.8) with similar to 68% of the total emission contributed by nitritation. Emissions increased with higher nitrite accumulation and lower organic carbon to nitrogen ratio. Yet, higher DO levels (similar to 2.2 mg O-2/L) lowered the aerobic N2O emission and weakened the dependency on nitrite concentration, suggesting a shift in N2O production pathway. The most effective N2O mitigation strategy combined intermittent patterns of aeration, anoxic feeding and anoxic carbon dosage, decreasing emission by over 99% (down to similar to 0.12% of the ammonium nitrogen loading). Without anaerobic digestion, mitigated Nit/DNit decreases the operational carbon footprint with about 80% compared to N/DN. With anaerobic digestion included, about 4 times more carbon is sequestered. In conclusion, the low CODrem/N-rem feature of Nit/DNit no longer offsets its environmental sustainability provided the process is smartly operated. (c) 2017 Elsevier Ltd. All rights reserved.

【 授权许可】

Free