TY - JOUR
T1 - Nitrogen removal as nitrous oxide for energy recovery
T2 - Increased process stability and high nitrous yields at short hydraulic residence times
AU - Wang, Zhiyue
AU - Woo, Sung Geun
AU - Yao, Yinuo
AU - Cheng, Hai Hsuan
AU - Wu, Yi Ju
AU - Criddle, Craig S.
N1 - Funding Information:
This research was supported by the U.S. National Science Foundation Engineering Research Center Reinventing the Nation’s Urban Water Infrastructure (ReNUWIt) [grant number EEC-1028968 ], and by the National Cheng Kung University North America Alumni Association and Foundation. The initial construction of the pilot-scale reactor was supported by an Innovation Transfer Grant from TomKat Center for Sustainable Energy . We are extremely grateful to Delta Diablo for financial and operational support of the pilot-scale system as a partner on EPA Grant [ EPA-R9-WTR3-13-001 , grant number 99T07401 ]. We thank Gary Darling, Amanda Roa, Nick Steiner and Operations, Lab and Maintenance staff.
Funding Information:
This research was supported by the U.S. National Science Foundation Engineering Research Center Reinventing the Nation's Urban Water Infrastructure (ReNUWIt) [grant number EEC-1028968], and by the National Cheng Kung University North America Alumni Association and Foundation. The initial construction of the pilot-scale reactor was supported by an Innovation Transfer Grant from TomKat Center for Sustainable Energy. We are extremely grateful to Delta Diablo for financial and operational support of the pilot-scale system as a partner on EPA Grant [EPA-R9-WTR3-13-001, grant number 99T07401]. We thank Gary Darling, Amanda Roa, Nick Steiner and Operations, Lab and Maintenance staff.
Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2020/4/15
Y1 - 2020/4/15
N2 - The Coupled Aerobic-anoxic Nitrous Decomposition Operation (CANDO) is a two-stage process for nitrogen removal and resource recovery: in the first, ammonia is oxidized to nitrite in an aerobic bioreactor; in the second, oxidation of polyhydroxyalkanoate (PHA) drives reduction of nitrite to nitrous oxide (N2O) which is stripped for use as a biogas oxidant. Because ammonia oxidation is well-studied, tests of CANDO to date have focused on N2O production in anaerobic/anoxic sequencing batch reactors. In these reactors, nitrogen is provided as nitrite; PHA is produced from acetate or other dissolved COD, and PHA oxidation is coupled to N2O production from nitrite. In a pilot-scale study, N2O recovery was affected by COD/N ratio, total cycle time, and relative time periods for PHA synthesis and N2O production. In follow-up bench-scale studies, different reactor cycle times were used to investigate these operational parameters. Increasing COD/N ratio improved nitrite removal and increased biosolids concentration. Shortening the anaerobic phase prevented fermentation of PHA and improved its utilization. Efficient PHA synthesis and utilization in the anaerobic phase correlated with high N2O production in the anoxic phase. Shortening the anoxic phase prevented reduction of N2O to N2. By shortening both phases, total cycle time was reduced from 24 to 12 h. This optimized operation enabled increased biomass concentrations, increased N2O yields (from 71 to 87%), increased N loading rates (from 0.1 to 0.25 kg N/m3-d), and shorter hydraulic residence times (from 10 to 2 days). Long-term changes in operational performance for the different bioreactor systems tested were generally similar despite significant differences in microbial community structure. Long-term operation at short anaerobic phases selected for a glycogen-accumulating community dominated by a Defluviicoccus-related strain.
AB - The Coupled Aerobic-anoxic Nitrous Decomposition Operation (CANDO) is a two-stage process for nitrogen removal and resource recovery: in the first, ammonia is oxidized to nitrite in an aerobic bioreactor; in the second, oxidation of polyhydroxyalkanoate (PHA) drives reduction of nitrite to nitrous oxide (N2O) which is stripped for use as a biogas oxidant. Because ammonia oxidation is well-studied, tests of CANDO to date have focused on N2O production in anaerobic/anoxic sequencing batch reactors. In these reactors, nitrogen is provided as nitrite; PHA is produced from acetate or other dissolved COD, and PHA oxidation is coupled to N2O production from nitrite. In a pilot-scale study, N2O recovery was affected by COD/N ratio, total cycle time, and relative time periods for PHA synthesis and N2O production. In follow-up bench-scale studies, different reactor cycle times were used to investigate these operational parameters. Increasing COD/N ratio improved nitrite removal and increased biosolids concentration. Shortening the anaerobic phase prevented fermentation of PHA and improved its utilization. Efficient PHA synthesis and utilization in the anaerobic phase correlated with high N2O production in the anoxic phase. Shortening the anoxic phase prevented reduction of N2O to N2. By shortening both phases, total cycle time was reduced from 24 to 12 h. This optimized operation enabled increased biomass concentrations, increased N2O yields (from 71 to 87%), increased N loading rates (from 0.1 to 0.25 kg N/m3-d), and shorter hydraulic residence times (from 10 to 2 days). Long-term changes in operational performance for the different bioreactor systems tested were generally similar despite significant differences in microbial community structure. Long-term operation at short anaerobic phases selected for a glycogen-accumulating community dominated by a Defluviicoccus-related strain.
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U2 - 10.1016/j.watres.2020.115575
DO - 10.1016/j.watres.2020.115575
M3 - Article
C2 - 32058151
AN - SCOPUS:85079157162
SN - 0043-1354
VL - 173
JO - Water Research
JF - Water Research
M1 - 115575
ER -